NEPAL NATIONAL BUILDING CODE
NBC 000 : 1994

REQUIREMENTS FOR STATE-OF-THE ART DESIGNAN INTRODUCTION

Government of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC000V0.RV1

10 May 1994

NEPAL NATIONAL BUILDING CODE
NBC 000 : 1994

This publication represents a standard of good practice and therefore
takes the form of recommendations. Compliance with it does not confer
immunity from relevant legal requirements, including bylaws
tTsflng >L % sf] ;/sf/ -dlGqkl/ifb\_ sf] ldlt @)^).$.!@ sf] lg0f{ofg';f/ :jLs[tGovernment of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC000V0.RV1

10 May 1994

iii

PrefaceThis Nepal National Building Code was prepared during 1993 as part of a bigger project to mitigate theeffect of earthquakes on the building of Nepal.
In 1988 the Ministry of Housing and Physical Planning (MHPP), conscious of the growing needs of
Nepal's urban and shelter sectors, requested technical assistance from the United Nations Development
Programme and their executing agency, United Nations Centre for Human Settlements (UNCHS).
A programme of Policy and Technical Support was set up within the Ministry (UNDP Project
NEP/88/054) and a number of activities have been undertaken within this framework.
The 1988 earthquake in Nepal, and the resulting deaths and damage to both housing and schools, again
drew attention to the need for changes and improvement in current building construction and design
methods.
Until now, Nepal has not had any regulations or documents of its own setting out either requirements orgood practice for achieving satisfactory strength in buildings.
In late 1991 the MHPP and UNCHS requested proposals for the development of such regulations anddocuments from international organisations in response to terms of reference prepared by a panel ofexperts.
This document has been prepared by the subcontractor's team working within the Department of
Building, the team including members of the Department and the MHPP. As part of the proposedmanagement and implementation strategy, it has been prepared so as to conform with the general
presentation requirements of the Nepal Bureau of Standards and Metrology.
The subproject has been undertaken under the aegis of an Advisory Panel to the MHPP.
The Advisory Panel consisted of :Mr. UB Malla, Joint Secretary, MHPP
Director General, Department of Building(Mr. LR Upadhyay)
Mr. AR Pant, Under Secretary, MHPP
Director General, Department of Mines & Geology(Mr. PL Shrestha)
Director General, Nepal Bureau of Standards & Metrology(Mr. PB Manandhar)
Dean, Institute of Engineering, Tribhuvan University(Dr. SB Mathe)
Project Chief, Earthquake Areas Rehabilitation &Reconstruction Project
President, Nepal Engineers Association
Law Officer, MHPP (Mr. RB Dange)
Representative, Society of Consulting Architectural &Engineering Firms (SCAEF)
Representative, Society of Nepalese Architects (SONA)
Deputy Director General, Department of Building,
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(Mr. JP Pradhan)

Member-Secretary

The Subcontractor was BECA WORLEY INTERNATIONAL CONSULTANTS LTD. of New
Zealand in conjunction with subconsultants who included :Golder Associates Ltd., Canada
SILT Consultants P. Ltd., Nepal
TAEC Consult (P.) Ltd., Nepal
Urban Regional Research, USA

A number of individual subconsultants and HMGN counterparts also provided input to the draft
Standards and other documents making up this Code. A particularly important contribution was madeby Dr.AS Arya, Professor Emeritus, University of Roorkee, India.

Revisions and Updated to this code came from:
Mr. Purna P.Kadariya, DG, DUDBC
Mr. Kishore Thapa, DDG, DUDBC
Mr. Mani Ratna Tuladhar, Sr. Div. Engineer, DUDBC
Mr. Jyoti Prasad Pradhan, Ex. DG, DOB
Mr. Bhubaneswor Lal Shrestha, Ex. DDG, DOB
Mr. Uttam Shrestha, Architect, Architects' Module Pvt.Ltd.
Mr. Manohar Lal Rajbhandhari, Sr. Structural Engineer, MR Associates
Mr. Amrit Man Tuladhar, Civil Engineer, DUDBC

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TABLE OF CONTENTS
Preface....................................................................................................................................... iii

0.

Foreword .......................................................................................................................vi

1

Scope...............................................................................................................................1
1.1

General...........................................................................................................................1
1.1.1
1.1.2
1.1.3
1.1.4

International State-of-the-Art (Part I) ............................................................................ 1
Professionally Engineered Structures (part II) ............................................................... 2
Mandatory Rules-of-Thumb (Part III) ........................................................................... 2
Guidelines for Remote Rural Buildings (Part IV) .......................................................... 2

HOW TO USE THIS NATIONAL BUILDING CODE ....................................................................4PART 1REQUIREMENTS FOR STATE-OF-THE-ART DESIGN ........................................6

1.1
1.2
1.3
1.4

Introduction...................................................................................................................6
Seismic Design ...............................................................................................................6
Other Loads ...................................................................................................................7
Materials ........................................................................................................................7

1.4.1
1.4.2
1.4.3

Reinforced Concrete................................................................................................................. 7
Steel ............................................................................................................................................ 8
Masonry..................................................................................................................................... 8

PART IIPROFESSIONALLY ENGINEERED STRUCTURES ...............................................9II.1

Introduction..................................................................................................................9PART III

MANDATORY RULES OF THUMB .........................................................................10

III-1
III-2
III-3

RC Building with Masonry Infills .............................................................................10
RC Building without Masonry Infills........................................................................10
Laod -Bearing Masonry .............................................................................................10

PART IVGUIDELINES ..............................................................................................................10

IV-1
IV-2

Rural Buildings : Low Strength Masonry ................................................................10
Rural Buildings : Earthen Buildings.........................................................................10

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0.

Foreword
This National Building Code is the first such document prepared in Nepal and it is intended thatits implementation be enforced through the Parliamentary Bill Act and concerned, local
authority by-laws.
Most countries which have successfully implemented building controls have only achieved itover a very long period which is normally measured in decades.
The technical documents making up building regulations are normally the subject of a continual
process of revision, correction and expansion as per requirements.
There is a strong movement towards uniform standards and many countries have adopted thoseof the International Standards Organisation in some areas. Where it has been consideredappropriate, the adoption of certain Indian Standards, with or without some modification has
been made in this document.
The degree to which national building codes and standards are enforced by law varies fromcountry to country. In some countries, the national building code is taken by the law courts as ameasure of good practice. India is one of the countries adopting such a system.
This first Nepal National Building Code has been produced by a team of Nepalese andinternational consulting engineers and architects and is based on the given term of reference.
It deals primarily with matters relating to the strength of buildings. However there are somechapters on site considerations and safety during construction and fire hazards.
Each section of this Code has been drawn up as a draft Standard for possible adoption by the
Nepal Bureau of Standards and Metrology. It has been proposed that the future revision and reissue of these sections be undertaken by the specialist committees brought together on a regularbasis by the Bureau. This system which has been adopted in Nepal for a number of years,
ensures that all special, general and public interest groups can give their full input to thisimportant regulatory process.
As of recent years, most of the uncontrolled building processes are rapidly producing structuresof unacceptable standard and prone to the risk of damage and collapse under earthquake. The
designs and personnel involved in the construction industry, industry, therefore, should adopt
this code sincerely so as to achieve a meaningful improvement in that standard of building
construction in Nepal.

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1

Scope
1.1

GeneralThis National Building Code provides both regulations and guidelines for theconstruction of buildings in all areas of Nepal.
This first version deals primarily with matters of strength. It is intended that, in time,revised versions of the National Building Code will be developed that will also
address the wider issues of planning, plumbing, electrical wiring, etc. In themeantime, the designer should observe such by-laws covering these matters as havealready been put in place by local authorities. Furthermore, designers should use
their professional judgement in recommending to their clients the adoption of
appropriate design standards used in similar countries to Nepal when there is yet no
Nepalese Standard for these disciplines.
The lack of an appropriate Nepal Standard should not be an excuse for poor design.
The four different levels of sophistication of design and construction that are being
addressed in this National Building Code are :••••International state-of-art
Professionally engineered structures
Buildings of restricted size designed to simple rules-of-thumbRemote rural buildings where control is impractical.

The first part of the Code describes how a potential designer should determine
which of the above levels should apply to the structure under consideration.
As the component Standards making up this Code may be revised from time to time
and the revisions adopted as part of the Code, the designer should check that thelatest version of the Code is being used.
Each of the four levels are introduced below.
1.1.1

International State-of-the-Art (Part I)
Because the major thrust of the Code is aimed at the typical and mostcommon buildings currently being erected in Nepal, it deliberately does
not suggest as being practical for everyday consideration thesophisticated design philosophies and analytical techniques that areappearing in the codes of more wealthy countries.
However, it is important that both Nepalese engineers and international
consultants who can produce such designs in a routine fashion and canensure that their designs can be built to the corresponding standards
should not be prevented from doing so. Moreover, these structures
should be seen to be meeting the Nepalese requirements with respect tominimum design loads andNBC105V2.RV5

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2
configuration. There is then no reason for any designer to ignore the
Nepal regulations in their entirety.
This part therefore describes some of the philosophy behind theselection of loads (in particular, the earthquake ones) and therefore
allows the sophisticated designer and/or international designer to build
up a design philosophy consistent with, and encompassing, the basic
requirements. The onus shall be on the designer to prove to the permitissuing authority that the Nepal Code requirements have been met
and/or exceeded.
It is important to note that the Nepal National Building Code's
requirements for seismic resistant are, in many cases, more onerous thanthose commonly practiced in other countries of the region.
1.1.2

Professionally Engineered Structures (part II)
This contains the standard code requirements that all professionallyqualified engineers will recognize and must meet as a minimum when
designing structures in Nepal. It covers all usual structures such as
hospitals, meeting halls, factories, warehouses, multi-story buildings andresidential buildings.
Materials, analysis and design,considerations are all covered.

1.1.3

construction

safetyandsite

Mandatory Rules-of-Thumb (Part III)
This part recognises that it is not practical in Nepal at present to insist
that all small buildings be designed for strength by a professional
adviser. Therefore, for classes of buildings not exceeding certain simple
criteria as to height, number of stories and floor area, mandatory rulesof-thumb are provided. The explanatory documents are such that anexperienced overseer will be able to understand them and present
sufficient details at the time of permit application to prove to a skilledappraiser at the Local Authority that the requirements have been met.
The requirements are in terms of limits on spans and heights, minimum
reinforcing and member sizes, positioning of earthquake-resistingelements and other such rules.

1.1.4

Guidelines for Remote Rural Buildings (Part IV)
These guidelines address about a dozen typical building styles that havebeen condensed from an inventory of approximately fifty-five surveyed
intensively during 1993. In the form of diagrams and descriptions aimed
at the technical advisers to owner/builders in villages, these guidelinesemphasized those changes that should be made to current practices toimprove the seismic resistance of these building which are not subject tomodern quantitative analysis and rational design consideration. These
structures are normally of

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earthen construction (unfired masonry, mud mortar, rubble, dry stone,
wattle and daub, etc).
Whereas these recommendations are described as guidelines, it isintended that it will be mandatory for such structures built in areas
controlled by a building permit-issuing local authority to comply withthem.
In addition, all such structures erected by departments and agencies ofGovernment of Nepal, regardless of their location in Nepal, shouldincorporate the recommendations of this section.

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HOW TO USE THIS NATIONAL BUILDING CODE
The fundamental documents of this Code are those of Part II- Professionally Engineered
Structures. In principle, all structures should be designed to meet the applicable provisions
appearing there.
Structures of certain common modern building types which do not exceed prescribed heightand plinth area limits will be deemed to have met the part II strength provisions if they havebeen detailed to the appropriate rules of thumb described in part III of this code.
Structures built of traditional local materials should not exceed three storeys in height. It ispreferable that all such structures incorporate strength features, described in the guidelines
forming Part IV of this Code. Structures of this type to be built in certain areas of Nepal where
local authorities have building permit systems in place will be required to incorporate suchdetails. All such structures funded by Government of Nepal and its agencies, departments andcorporations shall incorporate these features, whether or not there is such a local authority
requirement.
The strength design of any structure, whether or not it conforms to the limits, areas andbuilding types of the structures permissible under Part III and IV of this Code, will be
acceptable if it meets the requirements of Part II- Professionally Engineered Structures of thisCode.
Each application for permission to construct a structure designed to international standards or
Codes of Practice shall provide detailed proof that the requirements of Part I and II have been
met or exceeded both qualitatively and quantitatively.
Figure 1 describes the process that should be followed by a building designer in determining
which requirements should be met for a particular structure.

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LOCATIONY

LOCATIONCONTROLLED
BY LOCALAUTHORITYY

HMGN
DEPT, CORP,
INGO, ANDDONORNOWNER/FUNDERNPHYSICAL SIZE /IMPORTANCEY

MATERIALS /CONSTRUCTION
TYPEY

SOPHISTICATEDDESIGNREQUIRED> 3
STOREYS
ETC ?

N

N

> 3
STOREYSETC ?

YTRADITIONAL
MATERIALS &CONSTNN
Y

N

N

TRADITION
AL
MATERIALS& CONSTN

ADVISORY

MANDATORY /ADVISORY

MANDATORYMANDATORYMANDATORY

NBC APPLICABLE
PARTSPART I

PART IIPART IIIPART IIPROVISIONFOR STATEOF-THE ART
DESIGNPROFESSIONALLY ENGINEEREDSTRUCTURESMANDATORYRULES OFTHUMBGUIDELINES

Figure 1: Flow Chart Showing Minimum Design Requirements

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Y

6

PART 1
1.1

REQUIREMENTS FOR STATE-OF-THE-ART DESIGN

Introduction
This Part addresses the considerations that should be taken into account by designers whowish to design structures for Nepal by alternative methods to those described in Part II of thisCode. The onus is on the designer using alternative methods to demonstrate that the finishedstructure will meet or exceed, both qualitatively and quantitatively, the requirements of PartII.
The strength provisions of this National Building Code are controlled overall by the aim ofincreasing the safety of structures in Nepal under earthquake shaking.
The achievement of an acceptable level of safety requires the adoption of sound structuralconcepts and the realisation of these concepts through appropriate detailed design and the useof materials and construction practices meeting the assumptions used during design.
The designers of structures for Nepal should make sure that they are familiar with the qualityof materials and construction practices that will be available to them.
The following sections describe the background to the design practices adopted in part II ofthis National Building Code.

1.2

Seismic Design
Nepal is a highly seismic country, lying as it does at the interface between two of the world's
major tectonic plates. All parts of Nepal are at risk from the effects of severe ground shaking
and there have been many reminders of this within living memory. Kathmandu experienced
catastrophic damage in 1934 and approximately 60000 mainly residential buildings wereseverely damaged or collapsed in an earthquake in the East of Nepal in 1988.
The seismic risk in Nepal is greater than in the majority of neighbouring India and Tibet.
A state-of-the-art seismic hazard analysis was undertaken during 1992 and 1993. All available
geological evidence, instrumentally-recorded seismic city and historical writings wereconsidered in the formation of the forward-looking model which covered Nepal and extended
into neighbouring countries. This model and the resultant risk analysis are comprehensively
described in a report prepared as subcomponent I of the UNDP/UNCHS (Habitat)/HMGN
subproject NEP/88/054/21.03. Some indicative secondary hazard (landslides and liquefaction)
maps for Nepal, and in more details for the Kathmandu Valley, are also described.
Seismic zoning for Nepal was prepared as a result of the risk analysis and is incorporated in
the proposed draft standard for Seismic Design of Buildings in Nepal (NBC105). This is oneof the documents for professionally engineered design in Part II of this Code.

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The return period for the onset of damage for a typical building of ordinary importance has
been chosen as 50 years. The return period for the strength of buildings has been chosen as
300 years.
The basic philosophy adopted for seismic design is to :………..
The level of earthquake load for design is calculated from consideration of seismic zone,
location, structural type, natural period and foundation soil conditions. Structures with lessinherent ductility incur higher design loads.
Unusual structures, water retention structures, bridges and earthworks are not specificallycovered by this Code. For these, special studies should be undertaken based on the principles
embodied in the relevant sections of the Nepal National Building Code.

1.3

Other Loads
Occupancy and other environmental (wind and snow) loads have been addressed by proposed
draft Nepalese Standards which adopt the corresponding Indian Standards, with adjustments
for the particular Nepalese topology where appropriate. The loading described in these
Nepalese Standards shall be used for all engineered structures in Nepal except for when morereliable and comprehensive data is available for the specific site.
The draft Nepalese Standard for Wind Load (NBC 104) Provides references to what recorded
wind data is available for Nepal.
Information on maximum and minimum temperatures in Nepal are to be found in the
proposed draft Nepalese Standard for Steel Design (NBC 111) which modifies the IndianStandard IS 800:1984.

1.4

Materials
The principal construction materials addressed so far by the Nepal National Building Codeare Reinforced Concrete, Steel and Reinforced Masonry. The philosophies addressed by theStandards or Codes of practice for each are outlined below.
1.4.1

Reinforced Concrete
A modified version of the Indian Standard 1S 456:1978 has been adopted. This
provides design rules in accordance with the principles of Limit State Design.
No specific calculations are required to justify the ductility level chosen within the
Nepal Seismic Design Standard (NBC 105). Instead, detailing in accordance withthe requirements of IS 4326 (Code of Practice for Earthquake Resistant Design andConstruction of Buildings is required. These provisions will introduce generalductility into the reinforced concrete members of a frame, but will not necessarily
lead to the predictable hierarchy

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of failure that would be achievable under the much more onerous capacity design
approach.
For any other standard to be acceptable for the design of a professionally engineered
structure in Nepal, it must be shown to be at least as good as that described above.
1.4.2

Steel
A working stress method of design is prescribed by reference to a slightly modified
version of the Indian Standard 1S 800:1984.

1.4.3

Masonry
The use of burnt-brick-in-cement-mortar masonry as a structural element in a highly
seismic country like Nepal is not preferred and alternative materials should bechosen wherever possible.
However, it is inevitable that such masonry structures of limited size should be able
to be built in Nepal. A draft code of practice (NBC 109: Unreinforced Masonry) has
been developed specially for Nepal conditions. This sets out detailing rules whereby
the inclusion of non-calculated reinforcing steel both within the brickwork and in
reinforced concrete bands and lintels will improve the seismic resistance of such
structures. It must be accepted, however, that the seismic performance of a structure
so detailed may be less satisfactory than that of a comparable structure in reinforced
concrete or structural steel designed in accordance with the Nepal Standards for
those materials.
On the other hand, the use of suitably reinforced and grouted hollow concrete block
masonry is to be encouraged in Nepal. While no specific document has yet been
incorporated in this Code for the rational design of such structural elements, there
are a number of international documents, which could be used to determine typicalstrengths of this type of construction.
Ungrounded concrete masonry in cement mortar should be considered in the samemanner as burnt-brick masonry.

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PART IIPROFESSIONALLY ENGINEERED STRUCTURES

II.1 Introduction
This part describes the minimum standard, which shall be met by all structures, which
are required to be designed strength-wise by rational scientific methods.
Stand-alone documents in the form of proposed draft Nepalese Standards address eachof the aspects so far developed for Nepal.
The documents covering Site Considerations (NBC 108) and Fire Safety (NBC 107)are largely couched in advisory terms at this stage of their development.
A document on Construction Safety (NBC 114) has been included. Many of therecommendations of this document are also advisory.
Certain types of structure conforming to specific limits of area, height andconfiguration may be instead detailed to the Mandatory Rules-of-Thumb described inpart III of this National Building Code.
Structures to be built with traditional materials and by traditional methods are usually
very difficult, or impractical, to design rationally because of the variability of materials
and construction methods. Guidelines addressing the important strength features to be
included in such structures are presented in part IV of this Code.
The following aspects have been covered by the documents making up this Part:

Site Consideration (NBC 108)
Materials
Materials Specification
Unit Weight of Materials
Load Derivation
Occupancy LoadWind Load
Earthquake Loads and Design
Snow Load
Design Requirements
Masonry: Unreinforced
Plain and Reinforced Concrete

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TimberAluminium
SAFETYFire Safety
Construction Safety

PART III MANDATORY RULES OF THUMB
III-1

RC Building with Masonry Infills

III-2

RC Building without Masonry Infills

III-3

Load-Bearing Masonry

PART IV GUIDELINES
IV-1

Rural Buildings: Low Strength Masonry

IV-2

Rural Buildings: Earthen Buildings

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NEPAL NATIONAL BUILDING CODE
NBC 101 : 1994

MATERIALS SPECIFICATIONS

Government of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL
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NEPAL NATIONAL BUILDING CODE
NBC 101 : 1994

MATERIALS

SPECIFICATIONSThis publication represents a standard of good practice and therefore
takes the form of recommendations. Compliance with it does not confer
immunity from relevant legal requirements, including bylaws
tTsflng >L % sf] ;/sf/ -dlGqkl/ifb\_ sf] ldlt @)^).$.!@ sf] lg0f{ofg';f/ :jLs[tGovernment of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL
Reprinted : 2064

NBC101V2.RV8

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i

PrefaceThis Nepal Standard was prepared during 1993 as part of a project to prepare a draft National Building
Code for Nepal.
In 1988 the Ministry of Housing and Physical Planning (MHPP), conscious of the growing needs of
Nepal's urban and shelter sectors, requested technical assistance from the United Nations Development
Programme and their executing agency, United Nations Centre for Human Settlements (UNCHS).
A programme of Policy and Technical Support was set up within the Ministry (UNDP Project
NEP/88/054) and a number of activities have been undertaken within this framework.
The 1988 earthquake in Nepal, and the resulting deaths and damage to both housing and schools, again
drew attention to the need for changes and improvement in current building construction and design
methods.
Until now, Nepal has not had any regulations or documents of its own setting out either requirements orgood practice for achieving satisfactory strength in buildings.
In late 1991 the MHPP and UNCHS requested proposals for the development of such regulations anddocuments from international organisations in response to terms of reference prepared by a panel ofexperts.
This document has been prepared by the subcontractor's team working within the Department of
Building, the team including members of the Department and the MHPP. As part of the proposedmanagement and implementation strategy, it has been prepared so as to conform with the general
presentation requirements of the Nepal Bureau of Standards and Metrology.
The subproject has been undertaken under the aegis of an Advisory Panel to the MHPP.
The Advisory Panel consisted of :Mr. UB Malla, Joint Secretary, MHPP
Director General, Department of Building(Mr. LR Upadhyay)
Mr. AR Pant, Under Secretary, MHPP
Director General, Department of Mines & Geology(Mr. PL Shrestha)
Director General, Nepal Bureau of Standards & Metrology(Mr. PB Manandhar)
Dean, Institute of Engineering, Tribhuvan University(Dr. SB Mathe)
Project Chief, Earthquake Areas Rehabilitation &Reconstruction Project
President, Nepal Engineers Association
Law Officer, MHPP (Mr. RB Dange)
Representative, Society of Consulting Architectural &Engineering Firms (SCAEF)
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Representative, Society of Nepalese Architects (SONA)
Deputy Director General, Department of Building,(Mr. JP Pradhan)

MemberMember-Secretary

The Subcontractor was BECA WORLEY INTERNATIONAL CONSULTANTS LTD. of New
Zealand in conjunction with subconsultants who included :Golder Associates Ltd., Canada
SILT Consultants P. Ltd., Nepal
TAEC Consult (P.) Ltd., Nepal
Urban Regional Research, USA

Principal inputs to this standard came from :Mr. YK Parajuli, TAEC
Mr. D Bhattarai, Assoc. Prof. of Construction Management, IoE.
Mr. AM Tuladhar, DoB, HMGN
Mr. JK Bothara, TAEC
Dr. RD Sharpe, BECA (Team Leader)
Revisions and Updated to this code came from:
Mr. Purna P.Kadariya, DG, DUDBC
Mr. Kishore Thapa, DDG, DUDBC
Mr. Mani Ratna Tuladhar, Sr. Div. Engineer, DUDBC
Mr. Jyoti Prasad Pradhan, Ex. DG, DOB
Mr. Bhubaneswor Lal Shrestha, Ex. DDG, DOB
Mr. Uttam Shrestha, Architect, Architects' Module Pvt.Ltd.
Mr. Manohar Lal Rajbhandhari, Sr. Structural Engineer, MR Associates
Mr. Amrit Man Tuladhar, Civil Engineer, DUDBC

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TABLE OF CONTENTS
Preface..................................................................................................................................i0.

Foreword ...............................................................................................................iv

1

Scope .......................................................................................................................1

2

Interpretation.........................................................................................................1
2.1

General ......................................................................................................1

3

Materials.................................................................................................................1

4

Appropriate, Adopted or New Materials ............................................................1

5

Recycled/ Used Materials......................................................................................1

6

Storage of the Materials........................................................................................1

7

Transportation of Materials .................................................................................2

8

Methods of Test......................................................................................................2

9

List of Standards....................................................................................................2

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0.

Foreword
This Standard deals with the requisite quality and effectiveness of construction materials
used mainly in the building construction. It also deals with the storage of materials wherestorage has relevance to strength.
0.1

NBC101V2.RV8

Since the quality requirements and test methods used to determine the quality are
enumerated in the relevant materials standards, this standards provide a list of Nepal
Standards (NS) for key materials used in the building construction. A list of related
Indian Standards (IS) has been included for those materials for which Nepal
Standards (NS) do not exist as yet. When NS or IS prepare Standards for othermaterials having a bearing on the strength characteristics of the buildings, or revised
version of the existing Standard, these shall be deemed to be the requirement of thisStandard. If it exists, the requirements of NS will govern and be mandatory unlessthe designer has based his design on a standard other than NS. The use of
appropriate, adopted or new materials is encouraged, provided these materials havebeen proven to meet their intended purposes.

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1

Scope
The minimum requirements of building materials for buildings complying with the National
Building Code are set forth in this part of Standard. Criteria for accepting the use of
appropriate and adopted new materials are also outlined.

2

Interpretation
2.1

GeneralIn this Standard the word "shall" indicates a requirement that is to be adopted in order
to comply with the Standard, while the word "should" indicates recommended
practice.
Commentary clauses are prefaced by the letter C and the number of the appropriateclause subject to comment.

3

Materials
The use of materials confirming to NS or IS or any other approved standards agency shalldeem to have satisfied the requirements of this Standard. A list of such Nepal Standards andIndian Standards appear in section 9 below.

4

Appropriate, Adopted or New Materials
Any appropriate, adopted or new materials that are not covered by the provision of thisStandard may also be used in buildings requiring National Building code compliance,
provided that these materials are equivalent, or better in quality, strength, effectiveness, fire
resistance, durability, safety, maintenance and compatibility. Prior to the use of suchmaterials, it shall be the responsibility of the building owner, or the authorised
representative of the building owner, to obtain proof of equivalency.

5

Recycled / Used Materials
If recycled / used materials meet the requirements of the Standard, they may also be used.

6

Storage of the Materials
All building materials shall be stored in such a manner that no deterioration or loss or
impairment of their structural and other inherent properties takes place.

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7

Transportation of Materials
All building materials shall be transported so as not to impair their inherent properties.

8

Methods of Test
The testing of materials necessary to fulfill the requirements of this Standard shall be
carried out in accordance with the procedures laid down by NS. Where a NS procedure is
not available, the testing shall conform to the procedures stipulated by IS or any otherauthority of similar stature. The test are to be carried out by appropriately-competentpersons in a suitable laboratory. The list of Nepal Standards and Indian Standards formaterials, which appear in the following section, also stipulate the procedures for testing.

9

List of Standards
Table 9.1 lists those Standards which are mandatory as minimum requirements for buildings
designed to comply with other Nepal Standards for Engineered design.
The latest version of a Standard shall be used.

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Table 9.1 : LIST OF RELATED MATERIALS STANDARDSINDIAN STANDARDS
A. GENERAL
IS : 1911-1967 Schedule of unit weights ofbuildings materials (first revision)

NEPAL STANDARDSNBC 102-94 : Unit weight of Materials

B. CEMENT AND CONCRETE
1. Aggregates
IS : 383-1970 : Specification for coarse andfine aggregates from natural sources forconcrete (second revision)Specification for standard sand for testing of
cement
IS:2386 Methods of test for aggregates forconcrete:
IS: 2386 (Part I) - 1963, Part I: Particle
size and shape.
IS: 2386 (Part II) - 1963, Part II:
Estimation of deleterious materials andorganic impurities.
IS: 2386 (Part III) - 1963, Part III :Specific gravity, density, voids,
absorption and bulking.
IS: 2386 (Part IV) - 1963, Part IV :Mechanical properties.
IS: 2386 (Part V) - 1963, Part V:
Soundness.

IS: 2386 (Part VI) - 1963, Part VI :Measuring mortar making properties offine aggregate.

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INDIAN STANDARDSNEPAL STANDARDS

IS: 2386 (Part VII) - 1963, Part VII:
Alkali aggregate reactivity.
IS: 2386 (Part VIII) - 1963, Part VIII:
Petrographic examination.

IS: 2430 - 1969: Methods of sampling of
aggregates for concrete.
IS: 9103-1979 : Specification for admixtures forconcrete.
IS: 9142-1979 : Specification for artificial lightweight aggregates for concrete masonry units.

2. Cement

NS 49/2041 : Ordinary Portland
CementIS : 269-1976 : Specification for ordinary
and low heat Portland cement.
IS : 2645-1975 : Specification for integral
cement waterproofing compounds (First
revision).
IS : 8042-1978 : Specification for white
Portland cement (first revision).
IS : 8042-1978 : Specification for highstrength ordinary Portland cement.
3. MORTAR
IS : 2250-1980 Code of practice forpreparation and use of masonry mortar (firstrevision)
Cement and concrete sampling and methodsof test.

IS : 516-1959 : Methods of test for strengthof concrete.

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INDIAN STANDARDSNEPAL STANDARDSIS : 1199-1959 Methods of sampling andanalysis of concrete.
IS : 2770 (Part I) -1967 : Methods of testingbond in reinforced concrete.
Part I : Pullout test.
IS : 3085-1965 : Methods of test forpermeability of cement mortar and concrete.
IS : 5816-1970 : Methods of test for splitting
tensile strength of concrete cylinders.
IS : 6925-1973 : Methods of test for
determination of water soluble chlorides in
concrete admixtures.
IS : 8142-1976 : Methods of test for
determining setting times of concrete bypenetration resistance.

4. Precast concrete products
IS : 2185 Specification for concrete masonryunits :NS 119/2042 Hollow Cement Block

IS : 2185 (Part I) -1979 Part I : Hollow
and solid concrete blocks (Second
revision).
IS : 2185 (Part II) -1983, Part II : Hollow
and solid lightweight concrete blocks.
IS : 2185 (Part III) -1984, Part III :Autoclaved cellular (aerated) concrete
blocks (Under print).

IS : 5751-1984: Specification for precast
concrete coping blocks (First revision)(under print).

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INDIAN STANDARDSNEPAL STANDARDSIS : 5758-1984: Specification for precast
concrete kerbs (First revision) (under print).
IS : 5820-1970: Specification for precast
concrete cable covers.
IS : 6523-1983: Specification for precast
reinforced concrete door and window frames(First revision).
IS : 9872-1981: Specification for precast
concrete septic tanks.
IS : 9893-1981: Specification for precast
concrete blocks for lintels and sills.

C. ASBESTOS CEMENT PRODUCTS

IS: 459-1970: Specification for unreinforced
corrugated and semi-corrugated asbestos
cement sheets (second revision).
IS : 1626: Specification for asbestos cementbuilding pipes and pipe fittings, gutters andgutter fittings and roofing fittings:

IS : 1626 (Part I) -1980, Part I: Pipes andpipe fittings (first revision).

IS : 1626 (Part I) -1980, Part I: Pipes andpipe fittings (first revision).

IS : 1626 (Part II) -1980, Part II: Guttersand gutter fittings (first revision).

IS : 1626 (Part III) -1981, Part III:
Roofing accessories (first revision).

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INDIAN STANDARDSNEPAL STANDARDSIS : 2096-1966 : Specification forasbestos cement flat sheets.
IS : 2098-1964 : Specification forasbestos cement building boards.
IS : 5913-1970 : Methods of test forasbestos cement products.
IS : 6908-1975 : Specification forasbestos cement pipes and fittings forsewerage and drainage.
IS :7639-1975 : Method of samplingasbestos cement products.
IS :9627-1980 : Specification forasbestos cement pressure pipes (lightduty).

D. CONCRETE PIPESIS : 458-1971 : Specification for concrete
pipes (with and without reinforcement)(second revision).

NS 080/2042 :Hume Pipe

IS : 1916-1963 : Specification for steel
cylinder reinforced concrete pipes.

IS : 3597-1966 : Methods of test for
concrete pipes.

IS : 4350-1967 : Specification for concrete
porous pipes for under drainage.
IS:7319-1974:
Specification
forperforated concrete pipes.

IS : 7322-1974 : Specification for specials
for steel cylinder reinforced concrete
pipes.

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INDIAN STANDARDSNEPAL STANDARDS

E. BUILDING LIMES
IS : 712-1973 : Specification forbuilding limes (second revision).

NS 002/2036 Lime for construction

IS : 1624-1974 : Method of fieldtesting of building lime (first revision).
IS :3068-1975 : Specification for broken
brick (burnt-clay) coarse aggregates foruse in lime concrete (first revision):
IS :6932 (Part I)-1973 Part I Determinationof insoluble residue, loss on ignition,
insoluble matter, silicon dioxide, ferric andaluminum oxide, calcium oxide andmagnesium oxide.

IS : 6932 (Part II)-1973 Part II
Determination of carbon dioxide
content.

IS : 6932 (Part III)-1973 Part III
Determination of residue on slakingof quicklime.

IS : 6932 (Part IV)-1973 Part IV
Determination of fineness ofhydrated lime.

IS : 6932 (Part V)-1973 Part V
Determination of unhydrated oxide

IS : 6932 (Part VI)-1973 Part VI
Determination of volume yield of
quicklime

IS : 6932 (Part VII)-1973 Part VII
Determination of compressive andtransverse strength
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INDIAN STANDARDSNEPAL STANDARDSIS : 6932 (Part VIII)-1973 Part VIII
Determination of workability.
IS : 6932 (Part IX)-1973 Part IX NS 184/2045 Methods of sampling for
Dolomite, Magnesite, and allied minerals
Determination of soundness.
IS : 6932 (Part X)-1973 Part X
Determination of popping andputting of hydrated lime.
IS : 6932 (Part XI)-1983 Method oftest for building limes : Part XI
Determination of setting time ofhydrated lime Stones
F. NATURAL BUILDING STONESIS : 1121 Method of test for determinationof strength properties of natural buildingstones:
IS : 1121 (Part I)-1974 Part I
Compressive
strength(firstrevision)

IS :1121 (Part II)-1974 Part II
Transverse strength (first revision).
IS :1121 (Part III)-1974 Part III
Tensile strength (first revision)

IS :1122 (Part IV)-1974 Part IV
Shear strength (first revision)

IS :1122-1974 Methods for determinationof true specific gravity of natural buildingstones (first revision)

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INDIAN STANDARDSNEPAL STANDARDSIS : 1123-1975 Method of identification ofnatural building stones (first revision)
IS:1125-1974 Method of test for
determination of weathering of naturalbuilding stones (first revision)
IS.1126-1974 Method of test determinationof durability of natural building stones(first revision)

IS:1127-1970
Recommendationsfordimensions and workmanship for naturalbuilding stones for masonry work (firstrevision)

IS : 1128-1974 Specification for limestone(slab and tiles) (first revision)

IS : 1130-1969 Specification for marble(blocks, slabs & tiles )IS.1706-1972 Method of determination ofresistance to wear by abrasion of naturalbuilding stones (first revision)

IS : 3316-1974 Specification for lateritestone block for masonry (first revision)

IS : 3620-1979 Specification for sandstone (slabs and tiles) (first revision)

IS: 4121-1967 Method of test for
determination of water transmission rate bycapillary action through natural buildingstones.
IS: 4348-1973 Methods of test for
determination of permeability of natural
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INDIAN STANDARDS
building stones (first revision)
IS:5218-1969 Method of test
toughness of natural building stones

NEPAL STANDARDSfor

IS: 5640-1970 Method of test for
determining the aggregates impact valueof soft coarse aggregates.
IS : 6250-1981 Specification for roofing
slate tiles (first revision).
IS : 7779 Schedule for properties andavailability of stones for construction
purposes:G.

1.

CLAY PRODUCTS
BUILDING

FOR

Bricks
IS : 1077-1976 Specification for common
burnt clay building bricks (third revision):

NS 1/2035 Brick

IS :3495 (Part I)-1976 Part I
Determination of compressive
strength (second revision)
IS :3495 (Part II)-1976 Part II
Determination of water absorption(second revision)
IS :3495 (Part III)-1976 Part III
Determination of efflorescence(second revision)
IS :3495 (Part IV)-1976 Part IV
Determination of warpage (second
revision)

IS : 5454-1978 Methods for sampling ofclay building bricks (first revision)

IS : 5779-1970 Specification for burnt
clay soling bricks.
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INDIAN STANDARDSNEPAL STANDARDS

IS: 6165-1971 Dimensions for special
shapes of clay bricks.

2. TilesIS: 654-1972 Specification for clay
roofing tiles, Mangalore pattern (second
revision)
NS 047/2041 Mosaic tiles
IS: 1464-1973 Specification for clay
ridge and ceiling tiles (first revision)
NS 0776/2041 Flooring tiles
IS : 1478-1969 Specification for clay
flooring tiles (first revision)
IS: 2690 Specification for burnt clay
flat terracing tiles:
IS: 8920-1978 Methods for samplingof burnt clay tiles
H. TIMBER TESTING
IS: 4907-1968 Method of testing timberconnectors .
IS: 8242-1976 Methods of test for
split bamboos.
IS: 8292-1976 Methods for evaluationof working qualities of timber under
different operations.
I. FLOOR COVERINGS AND OTHERFINISHES
IS: 777-1970 Specification for glazed
earthenware tiles (first revision)
IS: 1237-1980 Specification for cement
concrete flooring tiles (first revision)
IS : 1542-1977 Specification for sand forplaster (first revision).

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INDIAN STANDARDSNEPAL STANDARDS

IS :2333-1981 Specification for plaster ofParis (first revision)
IS : 3461-1980 Specification for PVC
asbestos floor tiles (first revision)
IS : 3462-1979 Specification for flexible
PVC flooring (first revision)

J. WATER PROOFING AND DAMPPROOFING MATERIALS

IS .1322-1982 Specification for bitumen
felts for waterproofing and damp
proofing (third revision)

IS:
1580-1969
Specificationforbituminous compound for waterproofing
and caulking purposes (first revision)

IS .3037-1965 Specification
bitumen mastic for use
waterproofing of roofs.

forin

IS :3384-1965 Specification for bitumen
primer for use in waterproofing anddamp-proofing.

IS :5871-1970 Specification for bitumen
mastic for tacking and damp- proofing
K. WOOD PRODUCTS
1. Plywood
IS :303-1975 Specification for plywood
for general purposes (second revision)

NS 38/2040 Plywood

NS 114/2042 Test methods of
Plywood.

IS : 1328-1982 Specification forveneered decorative plywood (second
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14
INDIAN STANDARDS
revision)

NEPAL STANDARDSIS : 4990-1981 Specification for plywood
for concrete shuttering work (firstrevision)
IS : 5509-1980 Specification for fire
retardant plywood (first revision)
2. Particle boards and fibre boards
IS: 1658-1977 Specification for fibre
hardboards (second revision)
IS : 1659-1979 Specification for blockboards (second revision)
IS: 2380 (Parts I to XXI)-1977 Methodsof test for wood particle boards andboards from other lignocellulosic
materials (first revision)
3. Doors and windows
IS : 1003 Specification for timber
panelled and glazed shutters:

IS :1003 (Part I)-1977 Part I Door
shutters (second revision)
IS : 1826-1961 Specification for
Venetian blinds for windows
IS : 2191 Specification for wooden
flush door shutters (cellular andhollow core type):
IS : 2191 (Part I)-1983 Part I
Plywood face panels (fourth
revision)
IS :2191 (Part II)-1983 Part II
Particle board face panels andhardboard face panels (thirdrevision)
IS : 2202 Specification for wooden flush
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15
INDIAN STANDARDS
doors shutters (solid core type):

NEPAL STANDARDSIS : 2202 (Part I)-1983 Part I
Plywood face panels (fourth
revision)
IS : 2202 (Part II)-1983 Part II
Particle board face panels andhardboard face panels (thirdrevision)
IS : 4020-1967 Methods of tests forwooden flush doors: Type tests .
IS : 4121-1983 Specification for timber
door, window and ventilator frames(second revision)
IS : 4962-1968 Specification for woodenside sliding doors.
IS : 6198-1983 Specification for legged,
braced and battened timber door shutters(1st rev.)L.

METAL DOOR AND WINDOWFRAMES, AND SHUTTERS
IS : 1038-1983 Specification for steel
doors, windows and ventilators (thirdrevision)
IS : 1361-1978 Specification for steel
windows for industrial buildings (firstrevision)
IS : 1948-1961 Specification foraluminum doors, windows and ventilators
IS : 1949-1961 Specification foraluminum windows for industrial
buildings.
IS . 4351-1976 Specification for steel
door frames (first revision)

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16
INDIAN STANDARDSNEPAL STANDARDSIS : 6248-1979 Specification for metalrolling shutters and rolling grills (firstrevision)
IS : 7452-1982 Specification for hot
rolled steel sections for doors, windows
and ventilators (first revision)
IS : 10451-1983 Specification for steel
sliding shutters (top hung type)
IS : 10521-1983
collapsible gates
M.

Specification

for

CONCRETE REINFORCEMENT
IS :432 Specification for mild steel andmedium tensile steel bards and hard
drawn
steel
wire
for
concretereinforcement:

IS :432 (Part I)-1982 Part I Mildsteel and medium tensile steel
bards (third revision)

NS 84/2042 Mild Steel Rod

IS :432 (Part II)-1982 Part II Harddrawn steel wire (third revision)

IS :1139-1966 Specification for hot
rolled mild steel, medium tensile steel
and high yield strength steel deformed
bards
for
concretereinforcement(revised)

IS :1566-1982 Specification for harddrawn steel wire fabric for concrete
reinforcement (second revision)

IS : 1785 Specification for plain harddrawn steel wire for prestressed concrete:

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INDIAN STANDARDSNEPAL STANDARDS

IS :1785 (Part I)-1983 Part I Colddrawn stress-relieved wire (second
revision)
IS : 1785 (Part II)-1983 Part II As
drawn wire (first revision)
NS 191/2046 Deformed steel bar andIS :1786-1979 Specification for cold wire for concrete reinforcement
worked steel high strength deformed bars
for concrete reinforcement (second
revision)
IS : 2090-1983 Specification for hightensile steel bars used in prestressed
concrete (first revision)
IS : 6003-1983 Specification for indented
wire for prestressed concrete (firstrevision)
IS : 6006-1983 Specification for uncoatedstress-relieved strand for prestressed
concrete (first revision)N.

STRUCTURAL STEELIS : 226-1975 Specification for structuralsteel (standard quality) (fifth revision)
IS : 961-1975 Specification for structuralsteel (high tensile) (second revision)
IS :1977-1975 Specification for structuralsteel (ordinary quality) (second revision)
IS : 2062-1984 Specification for weldable
structural steel (third revision) (underprint)

IS :2830-1975 Specification for carbon
steel billets, blooms and slabs for rerolling into structural steel (standard

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INDIAN STANDARDS
quality) (first revision)

NEPAL STANDARDS

IS :2831-1975 Specification for carbon
steel billets, blooms and slabs for rerolling into structural steel (ordinary
quality) (second revision)
IS : 8500-1977 Specification for weldable
structural steel (medium and highstrength qualities)

0.

BARS, RODS, WIRE AND WIRE
RODS
IS : 280-1978 Specification for generalengineering purposes (third revision)

IS : 1148-1982 Specification for hot
rolled steel rivet bars (up to 40 mm
diameter) for structural purposes (thirdrevision)

IS : 1149-1982 Specification for hightensile steel rivet bars for structural
purposes (third revision)

IS : 2591-1982 Dimensions for hot rolledbars for threaded components (second
revision)

IS :7887-1975 Specification for mild
steel wire rods for general engineering
purposesP.

PLATES
IS .3502-1979 Specification for steel
chequered plates

Q.

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TUBES AND TUBULARS

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19
INDIAN STANDARDSIS : 1161-1979 Specification for steel
tubes for structural purposes (thirdrevision)

NEPAL STANDARDS

IS :1239 Specification for mild steel
tubes, tubulars and other wrought steel
fittings:
IS :1239 (Part I)-1979 Part I Mildsteel tubes (fourth revision)
IS :1239 (Part II)-1982 Part II Mildsteel tubulars and other wroughtsteel pipe fittings (third revision)

IS : 4270-1983 Specification for steel
tubes used for water wells (first revision)

IS :4516-1968 Specification for ellipticalmild steel tubes.

IS :4923-1968 Specification for hollow
mild steel sections for structural use

IS : 733-1983 Specification for wrought
aluminum and aluminum alloys, bars,
rods and sections for general engineering
purposes (third revision)

IS : 737-1974 Specification for wrought
aluminum and aluminum alloys, sheet
and strip (for general engineering
purposes) (second revision)

IS : 738-1977 Specification for wrought
aluminum and aluminum alloy drawn
tube for general engineering purposes(second revision)

IS : 1254-1975 Specification for
corrugated aluminum sheet (second
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20
INDIAN STANDARDS
revision)

NEPAL STANDARDS

IS :1285-1975 Specification for wrought
aluminum and aluminum alloys, extruded
round tube and hollow sections (forgeneral engineering purposes) (second
revision)
IS : 7094-1973 Specification foraluminum alloys welded tubes for generalengineering purposes

R. WELDING ELECTRODES AND WIRESIS : 814 Specification for covered
electrodes for are welding of structuralsteels:
IS :814 (Part I)-1974 Part I for
welding products other than sheets(fourth revision)
IS :814 (Part II)-1974 Part II for
welding sheets (fourth revision)

IS : 815-1974 Classification and codingof covered electrodes for metal are
welding of structural steels (2nd Rev.)

IS : 1278-1972 Specification for filler
rods and wires for gas welding (second
revision)

IS : 1395-1982 Specification for low andmedium alloy steel covered electrodes formanual metal are welding (third revision)

IS :3613-1974 Acceptance tests for wireflux combinations for submerged-arc
welding of structural steel (first revision)
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21
INDIAN STANDARDSIS : 4972-1968 Specification
resistance spot-welding electrodes

NEPAL STANDARDSforIS :6419-1971 Specification for welding
rods and base electrodes for gas shielded
are welding of structural steel
IS : 6560-1972 Specification formolybdenum
andchromiummolybdenum low alloy steel welding rods
and base electrodes for gas shielded dare
welding.
IS :7280-1974 Specification for base wire
electrodes for submerged-are welding ofstructural steels
IS :.8363-1976 Specification for barewire electrodes for electroslag welding ofsteels.

S.

BOLTS, NUTS AND FASTENERSACCESSORIES

IS :207-1964 Specification for gate andshutter hooks and eyes (revised)
IS : 451-1972 Specification for steel
countersunk head wire nails (second
revision)

NS 167 : Part 3/2045 woodscrew part 3-slotted countersunk screw.

IS :724-1964 Specification for mild steel
and brass cup, ruler and square hooks andscrew eyes (revised)
IS : 730-1978 Specification for hookbolts for corrugated sheet roofing (second
revision)
IS .1120-1975 Specification for coachscrews (first revision)

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22
INDIAN STANDARDSNEPAL STANDARDSIS : 1363-1967 Specification for black
hexagonal bolts, nuts and lock nuts (dia.
6 to 39 mm) and black hexagonal screws(dia. 6 to 24 mm) (first revision)

IS : 1365-1978 Specification for slottedcountersunk head screws (third revision)

IS : 1366-1982 Specification for slottedcheese head screws (dia. range 1.6 to 20mm) (second revision)

IS : 2016-1967 Specification for plain
washers (second revision)

IS : 2389-1968 Specification for
precision hexagon bolts, screws, nuts andlock nuts (dia. range 1.6 to 5 mm) (firstrevision)

IS :2585-1968 Specification for blacksquare bolts and nuts (dia. range 6 to 39mm) and black square screws (dia. range
6 to 24 mm) (first revision)

IS :2687-1975 Specification for cap nuts
(first revision)
IS:3063-1972 Specification for single
coil rectangular section spring washers
for bolts, nuts and screws (first revision)

IS : 3468-1975 Specification for pipe
nuts (first revision)
IS :3753-1972 Specification for hightensile friction grip bolts (first revision)

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INDIAN STANDARDS
IS:4206-1967 Dimensions for nominal
lengths, and thread lengths for bolts,
screws and studs

NEPAL STANDARDSIS : 4762-1968 Specification for worm
drive hose clips for general purposes
IS : 5369-1975 General requirements forplain washers and lock washers (firstrevision)
IS:.5372-1975 Specification for taper
washer for channels (ISMC) (firstrevision)
IS :5373-1969 Specification for square
washers for wood fasteningsIS:5624-1970
foundation bolts

Specification

forIS:6113-1970
Specificationforaluminum fasteners for building purposes
IS :6610-1972 Specification for heavy
washers for steel structures
IS : 6623-1972 Specification for heavy
washers for steel structures
IS : 6639-1972 Specification
hexagon bolts for steel structures

for

IS : 6649-1972 Specification for hightensile friction grip washers

IS : 6733-1972 Specification for wall androofing nails
IS : 6736-1972 Specification for slottedraised countersunk head wood screws.

IS : 6739-1972 Specification for slottedround head wood screws

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24
INDIAN STANDARDS
IS: 6760-1972 Specification for slottedcountersunk head wood screws.

NEPAL STANDARDS

IS: 8033-1976 Specification for round
washers with square hole for wood
fastenings
IS :8412-1977 Specification for slottedcountersunk head bolts for steel
structures
IS:8822-1978 Specification for slotted
mushroom head roofing bolts
IS :8869-1978 Specification for washers
for corrugated sheet roofing
IS :8911-1978 Specification for slottedraised countersunk head screws
IS :10238-1982 Specification for stepbolts for steel structures
T.

SCREW THREADS AND RIVETS
IS :554-1975 Dimensions for pipe threads
where pressure tight joints are requiredon the threads (second revision)
IS :1929-1982 Specification for hot
forged steel rivets for hot closing (12 to
36 mm diameter) (first revision)
IS:.2155-1982 Specification for cold
forged solid steel rivets for hot closing (6to 16 mm diameter) (first revision)
IS :2643 Dimensions for pipe threads forfastening purposes:

IS :2643 (Part I)-1975 Part I Basic
profile and dimensions (firstrevision)
IS :2643 (Part II)-1975 Part II
Tolerances (first revision)
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INDIAN STANDARDSNEPAL STANDARDS

IS:2643 (Part III)-1975 Part III
Limits of sizes (first revision)
IS : 10102-1982 Technical supply
conditions for rivets
IS :2907-1964 Specification for cold
forged steel rivets for cold closing (1 to
16 mm diameter (first revision)U.

WIRE ROPES AND WIREPRODUCTS

IS :278-1978 Specification for galvanizedsteel barbed wire for fencing (thirdrevision)
IS : 1835-1976 Specification for steel
wire for ropes (third revision)
IS :2140-1978 Specification for stranded
galvanized steel wire for fencing (firstrevision)
IS :2266-1977 Specification for steel
wire suspension ropes for generalengineering purposes (second revision)
IS : 2365-1977 Specification for steel
wire suspension ropes for lifts, elevatorsand hoists (first revision)IS:2721-1979
Specificationforgalvanized steel wire chain link fences(first revision)
IS :3121-1981 Specification for rigging
screws and stretching screws (firstrevision)IS
NBC105V2.RV5:

6594-I977

Technical

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26
INDIAN STANDARDS
conditions for wire ropes and strands(first revision)V.

NEPAL STANDARDSGLASSIS : 2553-1971 Specification for safety
glass (second revision)
IS : 2835-1977 Specification for flattransparent sheet glass (second revision)
IS :5437-1969 Specification for wired
and figured glass.

W.

FILLERS, STOPPERS AND
PUTTIESIS : 110-1968 Specification for readymixed paint, brushing, grey filler, forenamels, for use over primers (1st rev.)
IS :345-1952 Specification for wood
filler, transparent, liquid
IS :419-1967 Specification for putty foruse on window frames (first revision)
IS : 3709-1966 Specification for mastic
cement for bedding of metal windows
IS :7164-1973 Specification for stopper

X. WATER BASED PAINTS

IS: 427-1965 Specification for distemper,
dry, colour as required (revised)
IS : 428-1969 Specification for
distemper, oil emulsion, colour as
required (first revision)

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27
INDIAN STANDARDSIS : 5410-1969 Specification for cement
paint, colour as required

NEPAL STANDARDSIS : 5411 Specification for plastic
emulsion paint:
IS : 5411 (Part I)-1974 Part I For
interior use.
IS : 5411 (Part II)-1972 Part II For
exterior use.
Y.

READY MIXED PAINTS AND
ENAMELS
IS :101-1964 Methods of test for readymixed paints and enamels (second
revision)
IS :102-1962 Specification for readymixed paint, brushing, red lead, nonsetting, priming (revised)
IS :104-1979 Specification for readymixed paint, brushing, zinc chrome,priming (second revision)
IS : 109-1968 Specification for readymixed paint, brushing, priming, plaster,to Indian Standard colours No. 361 and
631 (first revision)
IS : 111-1950 Specification for readymixed paint, brushing, undercoating,exterior, to Indian Standard colours No.
101,216,352,358,443 and 632
IS :112-1950 Specification for readymixed paint, spraying, undercoating,exterior, to Indian Standard colours No.
101,216,352,358,443 and 632

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28
INDIAN STANDARDSNEPAL STANDARDSIS : 113-1950 Specification for readymixed paint, brushing, undercoating,interior, to Indian Standard colours No.
101,216,352,358,443 and 632

IS :114-1950 Specification for readymixed paint, spraying, undercoating,interior, to Indian Standard colours No.
101,216,352,358,443 and 632
IS :115-1950 Specification for readymixed paint, brushing, undercoating,exterior, matt finish to Indian Standard
colours No. 352 and 632
IS:116-1950 Specification for readymixed paint, spraying, undercoating,exterior, matt finish, to Indian Standard
colours No. 352 and 632
IS : 117-1964 Specification for readymixed paint, brushing, finishing exterior,semi-gloss, for general purposes, toIndian Standard colours Light Colours
No. 101, 102, 174, 216, 217, 275, 281.
352, 353, 354, 358, 361, 364, 365, 384,
385, 386, 387, 388, 397, 442. 443, 628,
629, 630, 631, 693, 694 and 697; Dark
Colours No. 103, 104, 169, 219, 278,
280, 283, 359, 360, 362, 363, 410, 444,
632, 635 and 692 (revised)
IS :120-1962 Specification for readymixed paint, brushing, finishing, semigloss, for general purposes, to IndianStandard colours No.537,538, 540, 541,
570 and 574 (revised)
IS :121-1962 Specification for readymixed paint, brushing, finishing, semigloss, for general purposes, to IndianStandard colour No.414 (revised)
IS :122-1962 Specification for readymixed paint, brushing, finishing, semigloss, for general purposes, to Indian
NBC105V2.RV5

10 May 1994

29
INDIAN STANDARDSStandard colours No.411,412 and 413(revised)

NEPAL STANDARDSIS : 123-1962 Specification for readymixed paint, brushing, finishing, semigloss, for general purposes, to IndianStandard colours No.445,446, 448,449,
451 and 473; and red oxide (colour
unspecified) (revised)
IS :124 Specification for ready mixed
paint, brushing, finishing, semi-gloss, forgeneral purposes:
IS :124 (Part I)-1976 Part I (second
revision)

IS :124 (Part II)-1979 Part II (second
revision)
IS :124 (Part III)-1979 Part III
IS :126-1962 Specification for readymixed paint, brushing, finishing, exterior,semi-gloss, for general purposes, toIndian Standard colour No. 671 (revised)
IS :127-1962 Specification for readymixed paint, brushing, finishing, exterior,semi-gloss, for general purposes, while(revised)
IS : 128-1962 Specification for readymixed paint, brushing, finishing, semigloss for general purposes, black(revised)
IS : 129-1950 Specification for readymixed paint, brushing, finishing interior,oil gloss, for general purposes, to IndianStandard colours No. 101, 102, 103, 104,
169, 216, 217, 219, 352, 353, 354, 358,
NBC105V2.RV5

10 May 1994

30
INDIAN STANDARDS
359, 360, 361, 362, 363, 364, 410, 443,
444, 628, 629, 630, 631, 632, 633, 634
and 635

NEPAL STANDARDS

IS :133-1975 Specification for enamel,interior (a) undercoating, (b) finishing(second revision)
IS :137-1965 Specification for readymixed paint, brushing, matt or egg- shellflat, finishing, interior, to Indian Standard
colour, as required (revised)
IS :155-1950 Specification for readymixed paint, brushing, matt, black for use
on wood
IS :156-1950 Specification for readymixed paint, brushing, for use on floors,
colour as required
IS : 158-1981 Specification for readymixed paint, brushing, bituminous, black,lead-free, acid, alkali, and heat resisting(third revision)
IS :1 62-1950 Specification for readymixed paint, brushing, fire resistingsilicate type, for use on wood, colour as
required
IS : 168-1973 Specification for readymixed
paint,
air-drying
semiglossy/matt, for general purposes (second
revision).
IS :290-1961 Specification for coal tar
black paint (revised)
IS :341-1973 Specification for black
Japan, Types A, B and C (first revision)
IS : 641-1964 Specification for readymixed paint, brushing, finishing, interior,
NBC105V2.RV5

10 May 1994

31
INDIAN STANDARDS
semi-gloss, for general purposes, white(revised)

NEPAL STANDARDSIS : 871-1956 Specification for readymixed paint, brushing, finishing, egg
shell gloss, for interior use, to IndianStandard colours-Class A No. 218 andClass B No.221
IS : 872-1956 Specification for readymixed paint, brushing, finishing, egg
shell gloss, for interior use, to IndianStandard colours No. 412 and 413
IS : 1188-1957 Specification for readymixed paint, brushing, oil gloss, genuine
zinc oxide, for general purposes
IS : 1232-1964 Specification for readymixed paint, brushing, yellow ochre,semi-gloss, for general purposes (revised)
IS : 2074-1979 Specification for readymixed paint, red oxide-zinc chrome,priming (first revision)

IS : 2075-1979 Specification for readymixed paint, shoving, red oxide-zinc
chrome, priming (first revision)
IS:2339-1963
Specificationforaluminum paint for general purposes, indual container
IS : 2932-1974 Specification for enamel,synthetic, exterior, (a) undercoating, (b)finishing (first revision)
IS : 2933-1975 Specification for enamel,exterior (a) undercoating, (b) finishing
NBC105V2.RV5

10 May 1994

32
INDIAN STANDARDS(first revision)

NEPAL STANDARDSIS : 3536-1966 Specification for readymixed paint, brushing, wood primer, pink

IS :3537-1966 Specification for readymixed paint, finishing, interior for
general purposes, to Indian Standard
colours
IS : 3539-1966 Specification for readymixed paint, undercoating, for use under
oil finishes, to Indian Standard colours,
as required
IS : 3585-1966 Specification for readymixed paint, aluminum brushing,priming, water resistant, for wood work
IS :3678-1966 Specification for readymixed paint, thick white, for lettering
IS :3678-1966 Specification for readymixed paint, thick white, for lettering
IS : 8662-1966 Specification for enamel,synthetic, exterior, (a) undercoating, (b)finishing, for railway coaches
IS :9862-1981 Specification for readymixed paint, brushing, bituminous black,lead free, acid, alkali, water and chlorine
resistingZ.

THINNERS AND SOLVENTSIS : 82-1973 Methods of sampling andtest for thinners and solvents for paints(first revision)
IS :324-1959 Specification for ordinary
denatured spirit (revised)
IS :533-1973 Specification for gum spirit

NBC105V2.RV5

10 May 1994

33
INDIAN STANDARDS
of turpentine (oil of turpentine) (firstrevision)AA.

NEPAL STANDARDSVARNISHES AND LACQUERS
IS :197-1969 Methods of sampling andtest for varnishes and lacquers (firstrevision)
IS : 337-1975 Specification for varnish,finishing, interior (first revision)
IS : 340-1978 Specification for varnish,mixing (first revision)
IS : 346-1952 Specification for varnish,spirit, clear, hard
IS : 347-1975 Specification for varnish,shellac, for general purposes (firstrevision)
IS : 348-1968 Specification for Frenchpolish (first revision)
IS : 349-1955 Specification for lacquer,
cellulose, nitrate, clear, finishing, glossy
for metal (first revision)
IS :524-1968 Specification for varnish,finishing, exterior, synthetic (firstrevision)
IS : 525-1968 Specification for varnish,finishing, exterior and general purposes(first revision)
IS : 642-1963 Specification for varnish
medium for aluminum paint (revised)

NBC105V2.RV5

10 May 1994

34
INDIAN STANDARDSNEPAL STANDARDS

NS 046/2041 Nails
NS 061/2041 Inch screw thread
NS 067/2041 Basic dimensionsof metric screw thread
AB.

OTHERS

NS 085/2042 Powder cement
pain
NS 112/2042 Enamel paintPart I For external use
Part IJ For internal use
NS 133/2043 Linseed oil (notedible)NS141/2043
corrugated sheet

Galvanized

NS 143/2043 Wood adhesive
based on polyvinyl acetate
dispersion
NS 157/2044 Hexagonal nuts
and bolts
Part I Basic dimensions
Part II Screw threads
NS 161/2044 Plastic emulsion
paintPart I For internal use
Part II for external use
NS 163/2045 Galvanized coating
on wireNS 167/2045 Wood screw
PartI
requirements

GeneralPart II Slotted rounded
counter sunk headPart III Slotted counter
NBC105V2.RV5

10 May 1994

35
INDIAN STANDARDSNEPAL STANDARDS
sunk headPart IV Slotted round headNS 168/2045 Galvanized steel
barbed wire
NS 169/2045 Mild steel wire
metal
NS 172/2045 Hinges
NS 177/2045 Methods of tests forready mixed paints and enamels
NS 180/2045 Dimensions for hot
rolled steel channel sections
NS 181/2045 Hardness
conversion tables for
NS 189/2046 Ready mixed paint,
aluminum, wood primer
NS 190/2046 Ready mixed
paint cement primer
NS 192/2046 Methods for Brinell
hardness tests for steel
NS 193/2046 Methods for
Vickers hardness tests for steel
NS 194/2046 Methods for
Rockwell hardness tests for steel
NS 199/2046 Galvanized steel
pipes for water supply
NS 202/2046 Bolts, screws studsnominal length and thread length
for general purpose bolts
NS 203/2046 Tensile testing of
metalsNS 205/2046 Ready mixed wood
NBC105V2.RV5

10 May 1994

36
INDIAN STANDARDSNEPAL STANDARDS
primer, pink, brushing

NS 206/2046 PVC pipe fordrinking water supply
NS 234/2047 Cold rolled
light structural steel
NS 246/2048 Vertically cast-castiron pipes
NS 254/2048 Cast iron pipes
centrifugally cast

NBC105V2.RV5

10 May 1994

37

NBC105V2.RV5

10 May 1994

38

NBC105V2.RV5

10 May 1994

NEPAL NATIONAL BUILDING CODE
NBC 102 : 1994

UNIT WEIGHT OF MATERIALS

Government of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC102V1.RV420 May 1994

NEPAL NATIONAL BUILDING CODE
NBC 102 : 1994

UNIT WEIGHT OF MATERIALSThis publication represents a standard of good practice and therefore
takes the form of recommendations. Compliance with it does not confer
immunity from relevant legal requirements, including bylaws
tTsflng >L % sf] ;/sf/ -dlGqkl/ifb\_ sf] ldlt @)^).$.!@ sf] lg0f{ofg';f/ :jLs[tGovernment of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC102V1.RV420 May 1994

3

PrefaceThis Nepal Standard was prepared during 1993 as part of a project to prepare a National Building Codefor Nepal.
In 1988 the Ministry of Housing and Physical Planning (MHPP), conscious of the growing needs of
Nepal's urban and shelter sectors, requested technical assistance from the United Nations Development
Programme and their executing agency, United Nations Centre for Human Settlements (UNCHS).
A programme of Policy and Technical Support was set up within the Ministry (UNDP Project
NEP/88/054) and a number of activities have been undertaken within this framework.
The 1988 earthquake in Nepal, and the resulting deaths and damage to both housing and schools, again
drew attention to the need for changes and improvement in current building construction and design
methods.
Until now, Nepal has not had any regulations or documents of its own setting out either requirements orgood practice for achieving satisfactory strength in buildings.
In late 1991 the MHPP and UNCHS requested proposals for the development of such regulations anddocuments from international organisations in response to terms of reference prepared by a panel ofexperts.
This document has been prepared by the subcontractor's team working within the Department of
Building, the team including members of the Department and the MHPP. As part of the proposedmanagement and implementation strategy, it has been prepared so as to conform with the general
presentation requirements of the Nepal Bureau of Standards and Metrology.
The subproject has been undertaken under the aegis of an Advisory Panel to the MHPP.
The Advisory Panel consisted of :Mr. UB Malla, Joint Secretary, MHPP
Director General, Department of Building(Mr. LR Upadhyay)
Mr. AR Pant, Under Secretary, MHPP
Director General, Department of Mines & Geology(Mr. PL Shrestha)
Director General, Nepal Bureau of Standards & Metrology(Mr. PB Manandhar)
Dean, Institute of Engineering, Tribhuvan University(Dr. SB Mathe)
Project Chief, Earthquake Areas Rehabilitation &Reconstruction Project
President, Nepal Engineers Association
Law Officer, MHPP (Mr. RB Dange)
Representative, Society of Consulting Architectural &Engineering Firms (SCAEF)

NBC102V1.RV4ChairmanMemberMemberMemberMemberMemberMemberMemberMemberMember

20 May 1994

4

Representative, Society of Nepalese Architects (SONA)
Deputy Director General, Department of Building,(Mr. JP Pradhan)

MemberMember-Secretary

The Subcontractor was BECA WORLEY INTERNATIONAL CONSULTANTS LTD. of New
Zealand in conjunction with subconsultants who included :Golder Associates Ltd., Canada
SILT Consultants P. Ltd., Nepal
TAEC Consult (P.) Ltd., Nepal
Urban Regional Research, USA

Revisions and Updated to this code came from:
Mr. Purna P.Kadariya, DG, DUDBC
Mr. Kishore Thapa, DDG, DUDBC
Mr. Mani Ratna Tuladhar, Sr. Div. Engineer, DUDBC
Mr. Jyoti Prasad Pradhan, Ex. DG, DOB
Mr. Bhubaneswor Lal Shrestha, Ex. DDG, DOB
Mr. Uttam Shrestha, Architect, Architects' Module Pvt.Ltd.
Mr. Manohar Lal Rajbhandhari, Sr. Structural Engineer, MR Associates
Mr. Amrit Man Tuladhar, Civil Engineer, DUDBC

NBC102V1.RV420 May 1994

5

TABLE OF CONTENTS
Preface............................................................................................................................................. 30

Foreword ............................................................................................................................... 6

1.

SCOPE ................................................................................................................................... 1

NBC102V1.RV420 May 1994

6

0 Foreword
This Nepal Standard for Unit Weight of Materials adopts the Indian Code IS:875 (Part 1) - 1987
Code fo Practice for Design Loads (Other than Earthquake) for Buildings and Structures, Part 1,
Dead Loads-Unit Weights of Building Materials and Stored Materials, (Second Revision).

NBC102V1.RV420 May 1994

1

1. SCOPEJUSTIFICATION FOR ADOPTING IS:875 (PART I)
During the desk study of codes from various countries (Uniform Building Code, Indonesian
Earthquake Code, National Building Code of Indian and Yugoslavian Code, New ZealandCode) it was found that unit weight of very common types of materials were maintained thesame in each country. For country-specific materials, their variation in unit-weight with respect
to those of similar materials in other countries was also found to be minimal. Because of theunavailability of specific unit weights of Nepalese materials for various uses, and because of thesimilarity of materials and their uses in Nepal and India, Indian Standard IS: 875 (Part I) -1987
has been recommended for adoption in Nepal.

NBC102V1.RV420 May 1994

NEAL NATIONAL BUILDING CODE
NBC 103 : 1994

OCCUPANCY LOAD
(IMPOSED LOAD)

Government of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC103V1.RV420 May 1994

NEPAL NATIONAL BUILDING CODE
NBC 103 : 1994

OCCUPANCY LOAD
(IMPOSED LOAD)

This publication represents a standard of good practice andtherefore takes the form of recommendations. Compliance with it
does not confer immunity from relevant legal requirements,
including bylaws
tTsflng >L % sf] ;/sf/ -dlGqkl/ifb\_ sf] ldlt @)^).$.!@ sf] lg0f{ofg';f/ :jLs[tGovernment of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC103V1.RV420 May 1994

i

PrefaceThis Nepal Standard was prepared during 1993 as part of a project to prepare a National Building Codefor Nepal.
In 1988 the Ministry of Housing and Physical Planning (MHPP), conscious of the growing needs of
Nepal's urban and shelter sectors, requested technical assistance from the United Nations Development
Programme and their executing agency, United Nations Centre for Human Settlements (UNCHS).
A programme of Policy and Technical Support was set up within the Ministry (UNDP Project
NEP/88/054) and a number of activities have been undertaken within this framework.
The 1988 earthquake in Nepal, and the resulting deaths and damage to both housing and schools, again
drew attention to the need for changes and improvement in current building construction and design
methods.

Until now, Nepal has not had any regulations or documents of its own setting out either requirements orgood practice for achieving satisfactory strength in buildings.
In late 1991 the MHPP and UNCHS requested proposals for the development of such regulations anddocuments from international organisations in response to terms of reference prepared by a panel ofexperts.
This document has been prepared by the subcontractor's team working within the Department of
Building, the team including members of the Department and the MHPP. As part of the proposedmanagement and implementation strategy, it has been prepared so as to conform with the general
presentation requirements of the Nepal Bureau of Standards and Metrology.
The subproject has been undertaken under the aegis of an Advisory Panel to the MHPP.
The Advisory Panel consisted of :Mr. UB Malla, Joint Secretary, MHPP
Director General, Department of Building(Mr. LR Upadhyay)
Mr. AR Pant, Under Secretary, MHPP
Director General, Department of Mines & Geology(Mr. PL Shrestha)
Director General, Nepal Bureau of Standards & Metrology(Mr. PB Manandhar)
Dean, Institute of Engineering, Tribhuvan University(Dr. SB Mathe)
Project Chief, Earthquake Areas Rehabilitation &Reconstruction Project
President, Nepal Engineers Association
Law Officer, MHPP (Mr. RB Dange)
Representative, Society of Consulting Architectural &Engineering Firms (SCAEF)
NBC103V1.RV4ChairmanMemberMemberMemberMemberMemberMemberMemberMemberMember
20 May 1994

ii
Representative, Society of Nepalese Architects (SONA)
Deputy Director General, Department of Building,(Mr. JP Pradhan)

MemberMember-Secretary

The Subcontractor was BECA WORLEY INTERNATIONAL CONSULTANTS LTD. of New
Zealand in conjunction with subconsultants who included :Golder Associates Ltd., Canada
SILT Consultants P. Ltd., Nepal
TAEC Consult (P.) Ltd., Nepal
Urban Regional Research, USA

Revisions and Updated to this code came from:
Mr. Purna P.Kadariya, DG, DUDBC
Mr. Kishore Thapa, DDG, DUDBC
Mr. Mani Ratna Tuladhar, Sr. Div. Engineer, DUDBC
Mr. Jyoti Prasad Pradhan, Ex. DG, DOB
Mr. Bhubaneswor Lal Shrestha, Ex. DDG, DOB
Mr. Uttam Shrestha, Architect, Architects' Module Pvt.Ltd.
Mr. Manohar Lal Rajbhandhari, Sr. Structural Engineer, MR Associates
Mr. Amrit Man Tuladhar, Civil Engineer, DUDBC

NBC103V1.RV420 May 1994

iii

TABLE OF CONTENTS
Preface ................................................................................................... i0

Foreward................................................................................................ iv

1

Scope ..................................................................................................... 1

NBC103V1.RV420 May 1994

iv

0 Foreword
This Nepal Standard for Occupancy Load adopts the Indian Code IS:875 (Part 2) - 1987 Code ofPractice for Design Loads (Other than Earthquake) for Buildings and Structures, Part 2 Imposed
Load, (Second Revision).

NBC103V1.RV420 May 1994

1

1. SCOPEJUSTIFICATION FOR ADOPTING IS:875 (PART I)
During the desk study of codes from various countries (Uniform Building Code, Indonesian
Earthquake Code, The National Building Code of Indian, the Yugoslavian Code and the New
Zealand Code) it was found that recommended occupancy loads were more or less similar. In
the absence of any specific information indicating that typical Nepalese occupancy loads are
unusually different, the Indian Standard IS: 875 (Part 2) -1987 has been recommended for
adoption in Nepal because of the similarity of the situations in Nepal and India..

7
NBC103V1.RV420 May 1994

NEPAL NATIONAL BUILDING CODE
NBC 104 : 1994

WIND LOAD

Government of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC103V1.RV420 May 1994

NEPAL NATIONAL BUILDING CODE
NBC 104 : 1994

WIND LOAD

This publication represents a standard of good practice andtherefore takes the form of recommendations. Compliance with it
does not confer immunity from relevant legal requirements,
including bylaws
tTsflng >L % sf] ;/sf/ -dlGqkl/ifb\_ sf] ldlt @)^).$.!@ sf] lg0f{ofg';f/ :jLs[tGovernment of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC103V1.RV420 May 1994

i
PrefaceThis Nepal Standard was prepared during 1993 as part of a project to prepare a National Building Codefor Nepal.
In 1988 the Ministry of Housing and Physical Planning (MHPP), conscious of the growing needs of
Nepal's urban and shelter sectors, requested technical assistance from the United Nations Development
Programme and their executing agency, United Nations Centre for Human Settlements (UNCHS).
A programme of Policy and Technical Support was set up within the Ministry (UNDP Project
NEP/88/054) and a number of activities have been undertaken within this framework.
The 1988 earthquake in Nepal, and the resulting deaths and damage to both housing and schools, again
drew attention to the need for changes and improvement in current building construction and design
methods.
Until now, Nepal has not had any regulations or documents of its own setting out either requirements orgood practice for achieving satisfactory strength in buildings.
In late 1991 the MHPP and UNCHS requested proposals for the development of such regulations anddocuments from international organisations in response to terms of reference prepared by a panel ofexperts.
This document has been prepared by the subcontractor's team working within the Department of
Building, the team including members of the Department and the MHPP. As part of the proposedmanagement and implementation strategy, it has been prepared so as to conform with the general
presentation requirements of the Nepal Bureau of Standards and Metrology.
The subproject has been undertaken under the aegis of an Advisory Panel to the MHPP.
The Advisory Panel consisted of :Mr. UB Malla, Joint Secretary, MHPP
Director General, Department of Building(Mr. LR Upadhyay)
Mr. AR Pant, Under Secretary, MHPP
Director General, Department of Mines & Geology(Mr. PL Shrestha)
Director General, Nepal Bureau of Standards & Metrology(Mr. PB Manandhar)
Dean, Institute of Engineering, Tribhuvan University(Dr. SB Mathe)
Project Chief, Earthquake Areas Rehabilitation &Reconstruction Project
President, Nepal Engineers Association
Law Officer, MHPP (Mr. RB Dange)
Representative, Society of Consulting Architectural &Engineering Firms (SCAEF)
Representative, Society of Nepalese Architects (SONA)
NBC103V1.RV4ChairmanMemberMemberMemberMemberMemberMemberMemberMemberMemberMember
20 May 1994

ii
Deputy Director General, Department of Building,(Mr. JP Pradhan)

Member-Secretary

The Subcontractor was BECA WORLEY INTERNATIONAL CONSULTANTS LTD. of New
Zealand in conjunction with subconsultants who included :Golder Associates Ltd., Canada
SILT Consultants P. Ltd., Nepal
TAEC Consult (P.) Ltd., Nepal
Urban Regional Research, USA

Principal inputs to this standard came from:Mr. YK Parajuli, TAEC
Mr. AS Arya, University of Roorkee, Roorkee, India
The Deputy Director- General, Metrological Department (IMD), India
Mr. S. Shrestha, TAEC
Mr. JK Bothara, TAEC
Dr. RD Sharpe, BECA (Team Leader)

Revisions and Updated to this code came from:
Mr. Purna P.Kadariya, DG, DUDBC
Mr. Kishore Thapa, DDG, DUDBC
Mr. Mani Ratna Tuladhar, Sr. Div. Engineer, DUDBC
Mr. Jyoti Prasad Pradhan, Ex. DG, DOB
Mr. Bhubaneswor Lal Shrestha, Ex. DDG, DOB
Mr. Uttam Shrestha, Architect, Architects' Module Pvt.Ltd.
Mr. Manohar Lal Rajbhandhari, Sr. Structural Engineer, MR Associates
Mr. Amrit Man Tuladhar, Civil Engineer, DUDBC

NBC103V1.RV420 May 1994

iii

TABLE OF CONTENTS
Preface .................................................................................................................................i0

Foreword.................................................................................................................iv

1

Scope ........................................................................................................................1

NEPAL AMENDMENTS TO IS : 875 (Part 3) - 1987.........................1
0

Foreword ............................................................................................1

1..............................................................................................14..............................................................................................35..............................................................................................3

6..............................................................................................48..............................................................................................4

APPENDIX D.................................................................................4

NBC103V1.RV420 May 1994

iv

0 Foreword
This Nepal Standard on "Wind Load" comprises the India Standard IS:875 (Part 3) 1987: CODEOF PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE) FOR
BUILDINGS AND STRUCTURES (Second Revision) with amendments as set out herein.
These amendments have been necessary to ensure the requirements of Nepalese context.
Particularly the wind zoning map of Nepal.

NBC103V1.RV420 May 1994

1

1. SCOPE
NEPAL AMENDMENTS TO BE: 875 (Part 3)-1987
0Foreword

Delete 0.1 to 0.3 and replace with:Wind speed is monitored at only a few stations in Nepal. The average monthly windspeed data recorded at a particular time of the day is available from 40 stations
distributed in various parts of the country. Of these, the station at Tribhuvan
International Airport 1030) records the average daily wind speed, maximum hourly
gust and maximum gust. The data from this station, however, is not continuous and thisinformation is available only for the period 1971 to 1975 and 1985 to 1986. For the
1985-1986 periods, only the average monthly wind speed is available. This is publishedin book-form. The general data is available in a booklet published by the Department ofHydrology and Meteorology.
The Snow and Glacier Hydrology Project and the Kagbeni Wind Power Project are two
projects which, at present, are measuring wind speed in some parts of the country. The
former has established three anemometer stations in Upper Langtang Valley, Khumbu(Everest region) and Modi Khola Valley (Annapurna region) where the hourly windspeed and direction have been measured since 1987. The project has further plans toestablish more stations in higher regions in the future. The latter was Nepal's first wind
power generation project. Maximum, minimum and average daily wind records since
1989 for Kagbeni in Mustang district of West Nepal are available. It is proposed toestablish eight more stations in various parts of the country.
The available data base is inadequate both in terms of spatial distribution and duration.
Modern wind design codes are based on the peak gust velocity averaged over a shortinterval of about 3 seconds that has a 50 year return period. The available Nepalesewind data base is insufficient and irrelevant to prepare wind zone map.
The Indian Standard IS : 875 (part 3) –1987 Code of practice for Design Wind Loadhas presented a wind zoning of India based on an average peak gust velocity of 3
seconds with a 50 year return period. According to this map, the plains have a basic
wind velocity of 47 meters per second and the hilly northern areas in Uttar Pradesh andHimanchal pradesh have a basic wind velocity of 39 meters per second-with amarginal adjustment for Dehra Dun for which the basic wind velocity is 47 meters per
second. The basic wind speed for the Laddakh region, which has high hills and valleys
all through it, is 55 meters per second.
In Nepal, the wind velocities in the lower valleys are smaller in magnitude than those in
the higher valleys and mountain ranges. This is evident from the speeds observed in
Kathmandu Valley and in Kali Gandaki Valley. It appears reasonable to classify
broadly the country into different wind zones for the purpose of setting the basic windspeeds. For this purpose, the Indian map has been used as a guide.

NBC104V1.RV8

20 May 1994

2
The country has been divided into two regions : a) the lower plains and hills and, b) themountains. The first zone generally includes the southern plains of the Terai, theKathmandu Valley and those regions of the country generally below an elevation of3000 meters. The second zone covers all sreas above 3000 meters. For the Nepaleseplains continuous with the Indian plans, a basic velocity of 47 m/s has been adopted. In
the higher hills, a basic wind velocity of 55 meters per second has been selected. The
wind zoning map of Nepal prepared on this basis is presented in Figure 1.1. While
preparing the map, the physical boundaries of the Districts have also been kept in mind.
Available wind data collected during the preparation of this standard is presented
separately in Appendices NBC 104: 1 to 5.
Note:
A.

Discussions with the Deputy Director General of India's metrological Department(IMD) by Dr AS Arya on the use of the available wind data for Nepal concluded
that the various parameters which control the peak gust velocities are extremely
variable in the hilly/mountainous regions of the Himalayas. In addition, any
extrapolation from average daily wind velocities and hourly mean velocities topeak gust velocities will be meaningless and, therefore, should not be attempted.

B.

The design wind velocity for a structure depends on the following main
parameters:•••

Probability factor,
Terrain, height and structure size factor, andTopography factor

These factors are fully described in IS:875 (Part 3)- 1987 and are easily
discernable for areas in Nepal. Therefore, it will be reasonable to use the IndianStandard for the computation of wind forces on structures in Nepal, taking thewind velocities as suggested here above.

1.1.3

C.

All organizations planning to build important light roof type structures or tallstructures are advised to collect data on wind direction and speed with the help of
appropriate instruments.

D.

Data and information collected during the course of preparing this Standard
appear in a separate Appendix, NBC: 104-2250

4th line, add "Indian" before codes.
5th line, replace "code" with "Standard"

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3
4
4.2. Delete this clause inclusively.
4.8 Add new clause:
4.8.1 In this Standard the word " shall" indicates a requirement that must be adopted inorder to comply with the Standard, while the word "Should" indicates recommended
practice.
5.
5.2. 2nd line, replace " India" with " Nepal".
Delete the last sentence.
5.3. Last sentence on note, replace " speed" with " speed".
5.3.1. Delete the first sentence and substitute with:
Figure 1 gives the approximate basis wind speed for Nepalese topography based on the
Indian territory. It is believed to be applicable for Category 2 at 10 m above the groundlevel, based on a 50 years mean return period.
5.3.2.1 (a) Delete the portion of note " Open sea coast land"
5.3.2.1 (b) Delete the last sentence of note.
Figure 1 Replace " the Map of India" with " the Map of Nepal".
Table 1 Delete k1 factor, and A and B coefficients for basic wind speeds of 33, 39, 44 and 50
m/s.
5.3.2.1 (c) Note- 3, delete the sentences.
5.3.3. Delete the first two sentences and replace with:
The basic wind speed given in Figure 1 is generally estimated from the height of theplaces above the mean sea level. Special attention has been given to the Kali Gandaki
River valley where the average wind velocity is extremely high. The boundaries ofDistricts have also been taken into consideration when demarcating the wind zones.
5.5. Delete this clause inclusively.

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4
6
6.2.2.9. Last sentences, replace " windword" with "windward".
8.
8.2. 5th line, insert "factor" before "at".
Note- 3rd line, replace "India" with "Nepal" andNote- 4th line, delete, "cyclone and".
APPENDIX D
4th paragraph, delete "likely to be found in India"

NBC104V1.RV8

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NEPAL NATIONAL BUILDING CODE
NBC 105 : 1994

SEISMIC DESIGN OF BUILDINGSIN NEPAL

Government of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

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NEPAL NATIONAL BUILDING CODE
NBC 105 : 1994

SEISMIC DESIGN OF BUILDINGSIN NEPAL
This publication represents a standard of good practice and therefore
takes the form of recommendations. Compliance with it does not confer
immunity from relevant legal requirements, including bylaws
tTsflng >L % sf] ;/sf/ -dlGqkl/ifb\_ sf] ldlt @)^).$.!@ sf] lg0f{ofg';f/ :jLs[tGovernment of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

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i

PrefaceThis Nepal Standard was prepared during 1993 as part of a project to prepare a draft National Building
Code for Nepal.
In 1988 the Ministry of Housing and Physical Planning (MHPP), conscious of the growing needs of
Nepal's urban and shelter sectors, requested technical assistance from the United Nations Development
Programme and their executing agency, United Nations Centre for Human Settlements (UNCHS).
A programme of Policy and Technical Support was set up within the Ministry (UNDP Project
NEP/88/054) and a number of activities have been undertaken within this framework.
The 1988 earthquake in Nepal, and the resulting deaths and damage to both housing and schools, again
drew attention to the need for changes and improvement in current building construction and design
methods.
Until now, Nepal has not had any regulations or documents of its own setting out either requirements orgood practice for achieving satisfactory strength in buildings.
In late 1991 the MHPP and UNCHS requested proposals for the development of such regulations anddocuments from international organisations in response to terms of reference prepared by a panel ofexperts.
This document has been prepared by the subcontractor's team working within the Department of
Building, the team including members of the Department and the MHPP. As part of the proposedmanagement and implementation strategy, it has been prepared so as to conform with the general
presentation requirements of the Nepal Bureau of Standards and Metrology.
The subproject has been undertaken under the aegis of an Advisory Panel to the MHPP.
The Advisory Panel consisted of :Mr. UB Malla, Joint Secretary, MHPP
Director General, Department of Building(Mr. LR Upadhyay)
Mr. AR Pant, Under Secretary, MHPP
Director General, Department of Mines & Geology(Mr. PL Shrestha)
Director General, Nepal Bureau of Standards & Metrology(Mr. PB Manandhar)
Dean, Institute of Engineering, Tribhuvan University(Dr. SB Mathe)
Project Chief, Earthquake Areas Rehabilitation &Reconstruction Project
President, Nepal Engineers Association
Law Officer, MHPP (Mr. RB Dange)
Representative, Society of Consulting Architectural &Engineering Firms (SCAEF)
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ChairmanMemberMemberMemberMemberMemberMemberMemberMemberMember
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ii

Representative, Society of Nepalese Architects (SONA)
Deputy Director General, Department of Building,(Mr. JP Pradhan)

MemberMember-Secretary

The Subcontractor was BECA WORLEY INTERNATIONAL CONSULTANTS LTD. of New
Zealand in conjunction with subconsultants who included :Golder Associates Ltd., Canada
SILT Consultants P. Ltd., Nepal
TAEC Consult (P.) Ltd., Nepal
Urban Regional Research, USA

Principal inputs to this standard came from :Mr. RD Jury, BECA
Dr. AS Arya, Professor Emeritus, University of Roorkee, India.
Dr. RD Sharpe, BECA (Team Leader)
Revisions and Updated to this code came from:
Mr. Purna P.Kadariya, DG, DUDBC
Mr. Kishore Thapa, DDG, DUDBC
Mr.Mani Ratna Tuladhar, Sr. Div. Engineer, DUDBC
Mr. Jyoti Prasad Pradhan, Ex. DG, DOB
Mr. Bhubaneswor Lal Shrestha, Ex. DDG, DOB
Mr. Uttam Shrestha, Architect, Architects' Module Pvt.Ltd.
Mr. Manohar Lal Rajbhandhari, Sr. Structural Engineer, MR Associates
Mr. Amrit Man Tuladhar, Civil Engineer, DUDBC

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TABLE OF CONTENTS

Preface ..................................................................................................................................................i0.

Foreword .................................................................................................................................. vi
0.1
0.2
0.3

Design Procedure ...................................................................................................................... vi
Related Codes............................................................................................................................ vi
Commentary ............................................................................................................................. vi

1

Scope..........................................................................................................................................1

2

Interpretation ............................................................................................................................2
2.1
2.2
2.3

3

General Principles of Ductile Seismic Design and Detailing .................................................6
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8

4

Structural System ...................................................................................................................... 6
Ductility...................................................................................................................................... 6
Energy Dissipation..................................................................................................................... 6
Symmetry ................................................................................................................................... 6
Uniformity of Storey Stiffness ................................................................................................... 6
Floor Diaphragms and Bracing................................................................................................. 6
Interconnection of Floors and Roof........................................................................................... 7
Interconnection of Foundations................................................................................................. 7

Design Methods & Load Combinations ...................................................................................7
4.1
4.2
4.3
4.4
4.5

5

General....................................................................................................................................... 2
Terminology............................................................................................................................... 2
Symbols ...................................................................................................................................... 4

General....................................................................................................................................... 7
Increase in Allowable Material Stresses for the Working Stress Method................................ 7
Increase in Allowable Soil Bearing Pressure............................................................................. 8
Design Load Combinations for the Working Stress Method ................................................... 8
Design Load Combinations for the Limit State Method .......................................................... 8

Methods of Analysis ..................................................................................................................8
5.1
5.2

General....................................................................................................................................... 8
Selection of Method of Analysis................................................................................................. 8

6

Seismic Weight ..........................................................................................................................97

Periods of Vibration ..................................................................................................................9

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8

Seismic Design Actions...........................................................................................................10
8.1

Design Spectra and Lateral Force Coefficients....................................................................... 10
8.1.1
8.1.2
8.1.3
8.1.4
8.1.5
8.1.6
8.1.7
8.1.8

8.2

Direction of Forces and Design Eccentricity........................................................................... 17
8.2.1
8.2.2

8.3

9

Vertical Seismic Forces............................................................................................................ 18

Derivation of Design Lateral Deformations ............................................................................ 18
Building Separations................................................................................................................ 18
9.2.1
9.2.2
9.2.3

9.3

To Boundaries........................................................................................................................... 18
Within Site ................................................................................................................................ 18
Separation Space Width........................................................................................................... 18

Inter-Storey Deflections........................................................................................................... 18

Seismic Coefficient Method ....................................................................................................19
10.1
10.2

11

Direction of Forces.................................................................................................................... 17
Design Eccentricity ................................................................................................................... 17

Deformation Due to Earthquake Forces................................................................................18
9.1
9.2

10

Design Horizontal Seismic Coefficient for the Seismic Coefficient Method............................ 10
Design Spectrum for the Modal Response Spectrum Method ................................................ 10
Basic Seismic Coefficient .......................................................................................................... 10
Basic Response Spectrum......................................................................................................... 11
Site Subsoil Category................................................................................................................ 11
Seismic Zoning Factor .............................................................................................................. 12
Importance Factor.................................................................................................................... 12
Structural Performance Factor................................................................................................ 15

Horizontal Seismic Base Shear................................................................................................ 19
Horizontal Seismic Forces ....................................................................................................... 19

Modal Response Spectrum Method........................................................................................19
11.1
11.2
11.3
11.4

Design Spectrum ...................................................................................................................... 19
Number of Modes to be Considered........................................................................................ 20
Combination of Modal Effects ................................................................................................ 20
Torsion ..................................................................................................................................... 20
11.4.1
11.4.211.4.3

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General...................................................................................................................................... 20
Static Analysis for Torsional Effects ........................................................................................ 20
Three-Dimensional Analysis..................................................................................................... 21

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12

Seismic Design Requirements for Secondary Structural Elements, Architectural Finishes
and Mechanical and Electrical Equipment...........................................................................21
12.1
12.2
12.3
12.4
12.5

General..................................................................................................................................... 21
Connections.............................................................................................................................. 21
Separation from Structural System ........................................................................................ 21
Services Cut-Offs ..................................................................................................................... 21
Design Forces ........................................................................................................................... 2212.5.1
12.5.2

12.6

Separation of Elements............................................................................................................ 25
12.6.1
12.6.213

Structure Response Factor....................................................................................................... 22
Component Seismic Performance Factor ................................................................................ 22

Applicable Elements ................................................................................................................. 25
Separation Requirements......................................................................................................... 26

Structural Variations to be Approved by Designer ................................................................26

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0.

Foreword
1.

Design Procedure
This Standard provides minimum requirements for the seismic design of structures
which are within the scope of this Standard as defined in 1.

2.

Related Codes
The requirements of this section of the Nepal Building Code shall be applied inconjunction with, IS 4326 - 1976 Code of Practice for Earthquake Resistant Design andConstruction of Buildings.
Where conflict exists between any requirements of this Standard and IS 4326, therequirements of this Standard shall be taken.

3.

Commentary
A commentary, which explains the reasons for many of the clauses in this Standard,
forms an accompanying volume to this document. This Standard should always be readin association with the Commentary.

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1

Scope

This standard sets down requirements for the general structural design and seismic design loadings forstructures within any of the following categories :(a)

All buildings having a floor area greater than 20 square metres.

(b)

Any building with a height greater than five metres.

(c)

All masonry or concrete walls greater than 1.5 metres in height.

(d)Elevated tanks of up to 200 cubic metres capacity. Larger tanks than this should be the subjectof a special study.

(e)All buildings to which the general public have access.

The requirements are not intended to apply to :(a)

Unusual buildings or structures (eg, those with unusual configurations or risk - such as nuclear
power stations, etc).

(b)

Civil engineering works (eg, bridges, dams, earth structures, etc).

(c)

Buildings or structures greater than 90 m in height.

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2

Interpretation
2.1

2.2

General
2.1.1

In this Standard the word "shall" indicates a requirement that must be adopted
in order to comply with the Standard, while the word "should" indicatesrecommended practice.

2.1.2

Commentary clauses (in Part 2) are prefaced by the letter C and the number of
the appropriate clause subject to comment.

Terminology
In this standard, unless inconsistent with the context :ANALYSIS METHODS :SEISMIC COEFFICIENT METHOD means a method of analysis using
static loads to simulate the effects of earthquake ground motion.
MODAL RESPONSE SPECTRUM METHOD means a method of dynamic
analysis in which a given earthquake design spectrum is applied to amathematical model of the structure and the response of several modes are
determined, and combined.
DEAD LOAD means the weight of all permanent components of a building including
walls, partitions, columns, floors, roofs, finishes and fixed plant and fittings that are an
integral part of the structure.
DESIGN means the use of rational computational or experimental methods inaccordance with the established principles of structural mechanics.
DIAPHRAGM means a member composed of a web (such as a floor or roof slab), ora truss which distributes forces to the horizontal load resisting system.
DUCTILITY means the ability of the building or member to undergo repeated andreversing inelastic deflection beyond the point of first yield while maintaining asubstantial proportion of its initial maximum load carrying capacity.
ELEMENTS includes primary and secondary elements :PRIMARY ELEMENTS means elements forming part of the basic load
resisting structure, such as beams, columns, diaphragms, or shear walls
necessary for the building's survival when subjected to the specified loadings.
SECONDARY ELEMENTS means elements such as intermediate orsecondary beams, partition walls, panels, or veneers not necessary for the

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survival of the building as a whole but which may be subject to stresses due toload applied directly to them or to stresses induced by the deformations of the
primary elements.
FRAME means a system composed of interconnected members functioning as acomplete self-contained unit with or without the aid of horizontal diaphragms or floor
bracing systems.
MOMENT RESISTING FRAME means a load carrying frame in which themembers and joints are capable of resisting horizontal loads through bending
moments.
HORIZONTAL LOAD RESISTING SYSTEM means that part of the structural
system to which the horizontal loads prescribed by this Standard are assigned.
LEVEL OF LATERAL RESTRAINT is the level at which the ground motion of theearthquake is transmitted to the structure by interaction between the foundationmaterials and the foundation elements by friction and bearing.
LIVE LOAD means the load assumed or known to result from the occupancy or useof a building and includes the loads on floors, loads on roofs other than wind, loads on
balustrades and loads from movable goods, machinery, and plant that are not an
integral part of the building.
SET BACK means any offset horizontally in from the plane of an exterior wall of astructure.
SHEAR WALL means a wall of any material required to resist horizontal loads
through the transfer of shear forces.
STOREY means the space between two adjacent floors or platform levels.

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2.3

Symbols

Symbols used in the Standard shall have the following meanings :bmaximum horizontal dimension of the building at the particular level measured
perpendicular to the direction of loadingC

basic seismic coefficient for the seismic coefficient methodC(Ti)ordinate of the basic response spectrum for translational period Ti

Cddesign horizontal seismic force coefficientCd(Ti)

ordinate of the design spectrum for translational period Ti

DLdesign dead loadD'overall length of the building at the base in the direction under consideration(m)dihorizontal displacement of the centre of mass at level i under the horizontal
seismic loading specified by this Standard (ie Fi)

E

design earthquake loaded

design eccentricity of the seismic load at a particular leveleccomputed eccentricity of the centre of mass from the centre of rigidity

Fihorizontal seismic force applied at a level designated as i

Fp

design seismic force for elements and components designed in accordance with
8g

acceleration due to gravity. To be taken as 9.81 m/s2

Hheight to the top of the main portion of the building or the eaves of the building(m)hiheight to the level designated as i from the level of lateral restraintI

importance factor for the building

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K

structural performance factor appropriate for the particular structural type

Kp

component seismic performance coefficient

LL

design live loadP

structural response factor

S

modal combination factor

SL

design snow, or ice load

T1

natural period of vibration of the first mode of the structureTitranslational period of vibration for mode iVtotal horizontal seismic base shear

Wi

proportion of Wt contributed by level iWpweight of the element, component or item of equipment

Wt

total of the gravity loads Wi above the level of lateral restraint

Z

seismic zoning factor

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3

General Principles of Ductile Seismic Design and Detailing
3.1

Structural System
Buildings shall be designed with a clearly defined (identifiable) load path, or paths, totransfer the inertial forces generated in an earthquake to the supporting soils.

3.2

Ductility
Buildings and all their seismic load resisting elements should be designed and detailed
to perform in a ductile manner.
Satisfactory ductility can be assumed if the structure will withstand, without significant
loss of vertical and/or lateral load carrying capacity, the lateral deflections specified in
9.1 applied through several reversals (cycles).
For the purposes of this Standard the above general requirement may be assumed to beadequately met if the specific requirements of Table 8.2 are complied with.

3.3

Energy Dissipation
In addition to the provision of adequate ductility, structures should also be designed toprevent the concentration of the demand for ductility in a few members, except where
special provisions are made to increase the ductility available in those members.
The demand for ductility should be spread throughout the structure so that theearthquake induced energy is dissipated uniformly.
For the purpose of this Standard the above general requirements may be assumed to beadequately met if the specific requirements of Table 8.2 are complied with.

3.4

Symmetry
The seismic load resisting elements of a structure should be located, as nearly aspracticable, symmetrically about the centre of mass of the structure.
Re-entrant angles in the plan shape of a structure should be avoided.

3.5

Uniformity of Storey Stiffness
Significant changes in the stiffness over the height of the building should be avoided.

3.6

Floor Diaphragms and Bracing
The horizontal bracing system or diaphragm at each floor shall be designed to distributeforces to the individual elements of the horizontal load resisting system in proportion totheir rigidities.

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3.7

Interconnection of Floors and RoofConcrete and masonry walls shall be anchored to all floors or roofs that are required toprovide them with horizontal support or stability. Such anchorage shall be designed forthe loads determined from 12, or a minimum load of 3 kN per metre of wall, whicheveris greater. Spacing of such anchors shall not exceed one metre unless the wall isdesigned to span between them.
Such connections to walls shall also comply with the requirements of 12.2.

3.8

Interconnection of Foundations
Individual foundations of a building shall be interconnected in two directions, generally
at right angles, by members designed for an axial tension and compression equal to 10% of the maximum vertical load on either foundation under seismic conditions.
If the axial load on one of the interconnected foundations is less than 20 % of that on
the other, the design axial load in the interconnecting elements shall be taken as 10 % of
the average vertical load on the two foundations under seismic conditions.

4

Design Methods & Load Combinations
4.1

GeneralDesign for earthquake actions shall be in accordance with either :(a)

The Working Stress Method (elastic method), or(b)

The Limit State Method

provided that reinforced concrete design shall be in accordance with the Limit State
Method unless specifically noted otherwise.
4.2

Increase in Allowable Material Stresses for the Working Stress Method
Whenever earthquake forces are considered along with other design forces, theallowable material stresses may be increased by one third but shall not exceed thefollowing limits :NBC105V2.RV5(a)Steels with a definite yield stress; the yield stress(b)

Steels without a definite yield stress; 80 percent of the ultimate strength or the
0.2 percent proof stress whichever is smaller.

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8
4.3

Increase in Allowable Soil Bearing Pressure
Whenever earthquake forces are considered along with other design forces, theallowable soil bearing pressures may be increased by up to 50 percent.

4.4

Design Load Combinations for the Working Stress Method
The design loads including earthquake for the Working Stress Method shall be not lessthan whichever of the following load combinations gives the greatest effect :DL + LL + E
0.7 DL + E
DL +SL + E

4.5

Design Load Combinations for the Limit State Method
The design loads including earthquake for the Limit State Method shall be not less thanwhichever of the following load combination gives the greatest effect :DL + 1.3 LL + 1.25 E
0.9 DL + 1.25 E
DL + 1.3 SL + 1.25 E

5

Methods of Analysis
5.1

GeneralAnalysis for the design earthquake actions shall be in accordance with one of thefollowing methods :(a)

The Seismic Coefficient Method as outlined in 10, or,(b)

The Modal Response Spectrum method as outlined in 11.

Note : Analysis using numerical integration time history procedures is not covered bythis Standard.
5.2

Selection of Method of Analysis
For structures of up to 40 m in height the Seismic Coefficient Method may be used. For
all other structures the Modal Response Spectrum Method shall be used.

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The Modal Spectrum Method should be used for :6a)Buildings with irregular configurations(b)

Buildings with abrupt changes in lateral resistance(c)

Buildings with abrupt changes in lateral stiffness with height(d)

Buildings with unusual shape, size or importance.

Seismic WeightThe seismic weight at each level, Wi, shall be taken as the sum of the dead loads and the seismic
live loads between the mid-heights of adjacent storeys.
The seismic live load shall be taken as a percentage of the design live load as given in Table
6.1.
Design Live Load

Percentage of Design Live Load

Up to 3 kPa
Above 3 kPa and for vehicle garages
For Roofs

25
50
NIL
Table 6.1

The seismic weight for roofs shall include allowance for ice if appropriate.

7

Periods of Vibration
7.1

The periods of vibration, Ti, shall be established from properly substantiated data, orcomputation, or both.

7.2

Where the Seismic Coefficient Method is used, the fundamental translation period in
the direction under consideration, Ti, shall be determined from :_____________
Ti = 2 π √ Σ Wi di2 /g Σ Fi di
7.1
where di may be calculated ignoring the effects of torsion.

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10
7.3

For the purposes of initial member sizing, the following approximate formulae for Ti
may be used :
(a)

(b)

For framed structures with no rigid elements limiting the deflection :T1 = 0.085 H ¾ for steel frames

7.2

T1 = 0.06 H ¾ for concrete frames

7.3

For other structures :T1 =0.09 H-----√D'

7.4

If T1 calculated using these equations is greater than 120 percent of that finallycalculated using Equation 7.1, the seismic forces shall be re-assessed.

8

Seismic Design Actions
8.1

Design Spectra and Lateral Force Coefficients
8.1.1

Design Horizontal Seismic Coefficient for the Seismic Coefficient Method
The design horizontal seismic force coefficient, Cd shall be taken as :Cd = CZIK

8.1

Where C is the basic seismic coefficient for the fundamental translational period
in the direction under consideration.
8.1.2

Design Spectrum for the Modal Response Spectrum Method
The design spectrum, Cd (Ti), shall be taken as :Cd (Ti) = C (Ti) ZIK

8.2

Where C (Ti) is the ordinate of the basic response spectrum for translational
period, Ti.
8.1.3

Basic Seismic Coefficient
The basic seismic coefficient, C, shall be determined from Figure 8.1 for theappropriate site subsoil category using the fundamental structural period
determined in accordance with 7.2 for the direction under consideration.

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11
8.1.4

Basic Response Spectrum
The basic spectrum, C(Ti), shall be determined from Figure 8.1 for theappropriate site subsoil category, and period, Ti.

8.1.5

Site Subsoil Category
The site shall be classified into one of the following site subsoil categories :Type I

Rock or Stiff Soil Sites.
Sites with bedrock, including weathered rock with an
unconfined compression strength greater than 500 kPa, overlain
by less than 20 m of :(a)very stiff cohesive material with an unconfinedcompression strength greater than 100 kPa, or(b)very dense cohesionless material with N > 30, where N is
the standard penetration (SPT) value.

Such sites will typically have a low amplitude natural period ofless than 0.2 s.
Type II

Medium Soil Sites
Sites not described as either Type I or Type III

Type IIISoft Soil Sites
Sites where the depth of soil of a particular type exceeds thefollowing values :a)Cohesive Soils

Cohesive Soil
Classification

Representative
undrained shear
strength (kPa)

Minimum
Depth of Soil
(m)

Soft

12.5 - 25

20

Firm

25 - 5025

Stiff

50 - 10040

100 - 200

60

Very Stiff
contd.../

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12b)

Cohesionless Soils

Cohesionless
Soils
Classification

Representative
SPT values(N)

Minimum
Depth of Soil
(m)

Loose

4 - 1040

Medium Dense

10 - 3045

Dense

30 - 50

55

Very Dense

> 50

60

Gravels> 30

100

Such sites will typically have a low amplitude natural period
greater than 0.6 s.
8.1.6Seismic Zoning Factor
The seismic zoning factor, Z, shall be obtained from Figure 8.2 for theappropriate location.

8.1.7

Importance Factor
The importance factor, I, for the structure shall be obtained from Table 8.1.

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Figure 8.1 : BASIC SEISMIC COEFFICIENT, C
BASIC RESPONSE SPECTRUM, C(TI)

13

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14
ZONE FACTORS FOR SELECTED MUNICIPALITIESMANICIPALITY
Shadrapur
Bharatpur
Bidur
Birendra Nagar
Biratnagar
Birganj
ButwalByas

FACTOR.Z
0.93
0.99
1.00
1.02
0.93
0.85
0.90
1.00

Damak
Dhanagadi
Dhanakuta

MUNICIPALITY
DharanDipayalGaur
IlamJanakpur
Kathmandu
Valley Towns
Mahendra
Nagar
Nepalganj
PokharaTulsipur

0.96
0.90
1.00

FACTCR.Z
1.00
1.10
0.82
0.97
0.89
1.00
0.91
0.91
1.00
1.00

0.8
0.9
1.0
1.1

0.8

1.1
1.0
Z = 1.1

0.8
1.1

0.9

0.8
0.8
1.0
0.8

Z = 1.0
1.0
Kathmandu
0.8
0.9

1.0

0.8

Outside of the shaded areas. the Seismic
Zoning Factor shall be determined byinterpolation between the contours.
Outside of the hatched areas, the Seismic
Zoning Factor shall be determined byinterpolation between the contours.

Figure 8.2 : SEISMIC ZONING FACTOR, Z

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15
Type of Building

Importance Factor I(a)Monumental Buildings

1.5

(b)

Essential facilities that should remain functional after anearthquake

1.5

Examples of these facilities would be :Hospitals and other medical facilities
Fire and Police stations
Emergency vehicle shelters/garages
Food storage structures
Emergency relief stores
Power stations (including standby power-generating
equipment for essential facilities)
Water works and water towers
Radio and television facilities
Telephone exchanges and transmission facilities
Offices and residential quarters for senior personnel requiredfor central and district-level rescue and relief operations(ministers, secretaries, police and army chiefs; CDO, LDO
and DDC chairmen, district-level army and police chiefs
Places of assembly (schools, colleges, cinemas, convention
halls, temples, dharmsalas).
(c)

(d)

(e)

Distribution facilities for gas or petroleum products in urban
areas.

2.0

Structures for the support or containment of dangerous
substances (such as acids, toxic substances, etc.).

2.0

Other structures
1.0
Table 0.1 : Importance Factor I
8.1.8

Structural Performance Factor
The minimum permissible value of the structural performance factor, K, andassociated detailing requirements shall be as given in Table 8.2.
In order to qualify for the K factors given in Table 8.2, the chosen structural
type shall meet the minimum detailing requirements shown.
The structural type may be different in each of two directions in a building andin that case the appropriate value for K shall be selected for each direction.

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16
When more than one structural type is used in the structure, for the direction
under consideration, the structural performance factor for the element providing
the majority of the seismic load resistance shall be applied provided that theelements of the other structural types have the ability to accept the resulting
deformations.

Item

Structural Type1.(a)Ductile moment-resistingframe

Must comply with the detailing for ductility
requirements.

Frame as in 1(a) withreinforced concrete shearwalls

For frames : as for 1(a).
Reinforced concrete shear walls must comply
with appropriate3 detailing for ductility
requirements.

Frame as in 1(a) witheither steel bracing
members detailed for
ductility or reinforced
concrete infill panels

For frames : as for 1(a).
Steel bracing members must comply with thedetailing for ductility requirements NBC 11194.
Reinforced concrete infill panels must comply
with the detailing requirements of NBC 10994.

Frame as in 1(a) withmasonry infills

Must comply with the detailing for ductility
requirements.

3.

Diagonally-braced steel
frame with ductile bracing
acting in tension only

Must comply with the detailing for ductility
requirements of Nepal Steel Construction
Standard

2.0

4.

Cable-stayed chimneys

Appropriate materials Standard

3.0

5.

Structures of minimal
ductility including
reinforced concrete
frames not covered by 1
or 2 above, and masonry
bearing wall structures.

Appropriate materials Standard

4.0

(b)

2.(a)

(b)

Minimum Detailing
Requirements

Structural
Performance
Factor K
1.0
1.01

1.51,2

2.01,2

cont..../

Table 0.2 :Structural Performance Factor K and other Design
Requirements for Horizontal Load-Resisting Systems of
Buildings and other Structures

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17
Table 8.2 continued
NOTES :

8.2

1

These factors shall apply only if the steel bracing members, the shear
walls and/or the infill panels are taken into consideration in both thestiffness and lateral strength calculations.

2.

These factors shall apply only if the frame acting alone is capable ofresisting at least 25 percent of the design seismic forces.

Direction of Forces and Design Eccentricity
8.2.1

Direction of Forces
For structures with seismic resisting systems located along two perpendicular
directions, the specified forces may be assumed to act separately along eachof these two horizontal directions. For other buildings, different directions ofapplication of the specified forces shall be considered so as to produce themost unfavourable effect in any structural element.

8.2.2

Design Eccentricity
The design eccentricity, ed , shall be determined as follows :(a)

If ec is less than 0.1 b and the building is 4 storeys or less in height :ed may be taken as equal to 0(b)

If ec is less than 0.3 b and 8.2.2(a) does not apply;
ed = ec + 0.1 b or ed = ec - 0.1 b

8.3

whichever is the most severe for the element under consideration.
(c)

NBC105V2.RV5

If ec is greater than 0.3 b, the structure should be analyzed using athree-dimensional modal response spectrum analysis with the mass ateach level displaced by ± 0.1 b, whichever is the most severe for theelement under consideration.

10 May 1994

18

8.3

Vertical Seismic Forces
The effect of the vertical components of seismic motion need not be considered indesign of a structure except as specified in 12. Where consideration of verticalseismic forces is required, the design vertical seismic coefficient shall be taken as
one half of the horizontal seismic coefficient given in 8.1.1.

9Deformation Due to Earthquake Forces
9.1

Derivation of Design Lateral Deformations
The design lateral deformations shall be taken as the deformations resulting from theapplication of the forces or design spectrum as specified in 10 or 11 respectively,
multiplied by the factor 5/K.

9.2

Building Separations
9.2.1

To Boundaries
Above ground level, each building of greater than three storeys shall have aseparation from the boundary, except adjacent to a designed street or publicway, of not less than the design lateral deflection determined in accordancewith 9.1 or 0.002 hi or 25 mm which ever is the greater.

9.2.2

Within Site
Parts of buildings or buildings on the same site which are not designed to act
as an integral unit shall be separated from each other by a distance of not lessthan the sum of the design lateral deflections determined in accordance with
9.1 or 0.004 hi or 50 mm which ever is the greater.

9.2.3

Separation Space Width
Separation spaces shall be detailed and constructed to remain clear of debris
and other obstructions. The width of such spaces shall allow for all
constructional tolerances.

9.3

Inter-Storey Deflections
The ratio of the inter-storey deflection to the corresponding storey height shall not
exceed 0.010 nor shall the inter-storey deflection exceed 60 mm (refer also to
12.6.2).

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19

10

Seismic Coefficient Method
10.1

Horizontal Seismic Base Shear
10.1.1 The horizontal seismic shear force acting at the base of the structure, in the
direction being considered, shall be :V = Cd Wt

10.1

where Cd is as defined in 8.1.1.

10.2

Horizontal Seismic Forces
10.2.1 The horizontal seismic force at each level i shall be taken as :Fi = V Wi hi / Σ Wi hi

10.2

Provided that :(a)Where the height to width ratio of the horizontal load resisting system
is equal to or greater than 3, then 0.1 V shall be considered asconcentrated at the top storey and the remaining 0.9 V shall be
distributed in accordance with the equation above.

(b)

For chimneys and smoke-stacks resting on the ground, 0.2 V shall beconsidered as concentrated at the top and the remaining 0.8 V shall be
distributed in accordance with the equation above.

(c)

For elevated tanks, the force Fi is equal to V and acts through thecentre of gravity of the total weight of the structure and contents.

10.2.2 The set of equivalent static forces specified in this clause shall be assumed toact simultaneously at each level in the direction being considered and shallbe applied through points eccentric to the centre of rigidity as specified in
8.2.2.

11

Modal Response Spectrum Method
11.1

Design Spectrum
The design spectrum used for the Modal Response Spectrum Method shall as given
in 8.1.2.
The relative response of each contributing mode i shall be determined by

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20
multiplying the mode response by the value of C(Ti) from 8.1.2.

11.2

Number of Modes to be Considered
A sufficient number of modes shall be considered to ensure that at least 90 % of themass is participating in the direction under consideration.

11.3

Combination of Modal Effects
11.3.1 An established method shall be used for the combination of modal effects.
11.3.2 The combination method shall take into account the effect of closely spacedmodes. Modes shall be considered to be closely spaced if their frequencies
are within 15 %.
11.3.3 The combined modal effects shall be scaled by the modal combination factor,
S, where :0.9 Cd Wt

S=

11.1

Σ combined modal base shears in the direction under consideration

provided that S shall not be taken as less than 1.0.

11.4

Torsion
11.4.1 General
An analysis for torsional effects may be conducted by the static method in
11.4.2.
For structures where ec is greater than 0.3 b, torsional effects should
evaluated using three-dimensional analysis and the provisions of 11.4.3.
11.4.2 Static Analysis for Torsional Effects
For a static analysis for torsional effects, the applied torsion at each level
shall use either the forces calculated by the Seismic Coefficient Method or
the combined storey inertial forces found in a translational two-dimensional
modal response spectrum analysis, and a design eccentricity, ed calculated inaccordance with 8.2.2.
Torsional effects shall be combined with the translational effects by direct
summation, with signs chosen to produce the most adverse combined effects
in the element under consideration.

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21
11.4.3 Three-Dimensional Analysis
For each direction of loading the position and distribution of the mass at eachlevel shall be adjusted to account for an eccentricity about the centre of massof ± 0.1 b. The sign of the eccentricity shall be that producing the largest
design actions in the element under consideration.

12

Seismic Design Requirements for Secondary Structural Elements,
Architectural Finishes and Mechanical and Electrical Equipment
12.1

GeneralAll architectural elements and mechanical and electrical systems shall meet therequirements of 12 as these may be a safety hazard in the event of an earthquake or
may be required to be functional immediately following such an event.
Contents of museums and similar items of historical or artistic value that are nonfunctional items should be restrained against seismic loads. Specialist advice should
be obtained for detailing such restraints.

12.2

Connections
All elements, components or equipment shall be positively connected to the structure
to resist the specified seismic loads. Friction due to gravity shall not be used toprovide the required resistance to horizontal loads.
Connections to ornamentations, veneers, appendages and exterior panels including
anchor bolts, shall be corrosion-resisting and ductile, with adequate anchorages. In
the case of precast concrete panels, anchorages shall be attached to, or hooked
around, panel reinforcing.

12.3

Separation from Structural System
Interaction with the structural system shall be avoided where specified in 12.6.1 byproviding adequate separations as defined in 12.6.2.

12.4

Services Cut-Offs
If continued operation of a facility during strong seismic motions presents anexcessive risk, an automatic shut-off system, which will operate at a pre-determinedground acceleration, not exceeding 0.2 g, shall be provided. In such cases, allequipment required for safe shut-down shall be capable of resisting the shut-off levelirrespective of other requirements of this Section.

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22

12.5

Design Forces
All elements and components shall be designed for a seismic force Fp, in any
direction given by :Fp = Cp P Kp Wp

12.1

For elements supported by the structure, Cp is equal to Cd for the structure
determined in accordance with 8.1.1 or 8.3 as appropriate.

For elements supported on the ground and independent of the structure, Cp is equal
to Cd determined in accordance 8.1.1 using the element fundamental period.
12.5.1 Structure Response Factor
The structural response factor, P, reflects the distribution and amplificationof the ground motion by the structure supporting the particular component
and shall be taken as :P = 1.0 + hi / H

12.2

P shall be taken as 1.0 for structures supported directly on the ground.
The P factor for more important elements of the structure should be
calculated from a more detailed analysis using the Modal Response Spectrum
Method.
12.5.2 Component Seismic Performance Factor
The component seismic performance factor, Kp is an allowance for both theestimated performance of the element or component and the importance of its
performance during and immediately following an earthquake. The value ofKp shall be obtained from Table 12.1.
If the period of vibration of an element is close to that of the structure,
considerable amplification may occur. If the ratio of the period of thestructure to that of the element is between 0.6 and 1.4, the value of Kp shallbe multiplied by 2 unless a special analysis is carried out.

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23

Kp

ELEMENT OR COMPONENTGROUP A
Secondary Elements or Components :1.

Walls and Partitions(a)Adjacent to an exit way, street or public placeor required to have a fire resistance rating.

4(b)Cantilevered walls and parapets.

4(c)

All walls not specified in 1(a), 1(b) or 2.

2.5

2.

Stairs and their enclosing shaft walls, and shaft
walls for lifts.

43.

Veneers, exterior prefabricated panels and ornamental
appendages, and their connections.

8

4.

Ceilings with tiles exceeding 2 kg in weight (Refer Note 5).
(a)
In an exit way or a ceiling required to have a fire rating.

3

(b)

2

5.

Other ceilings not included in 4(a).

Furniture
In an exit way or furniture that would pose a safety
hazard when subject to earthquake loads.

2

6.

Towers, chimneys or smoke stacks not exceeding 10 % of
the mass of the building (Refer Note 3).

2.5

7.

Penthouse or plant room structures on the top of astructure.

2.5

8.

Horizontally cantilevered floors, beams, sunshades, etc.
Note : The force acts vertically upward or downward.

5(continued on next page)

Table 12.1 : Component Seismic Performance Coefficient

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24

Kp

ELEMENT OR COMPONENTGROUP B
Mechanical and Electrical Components :9.

Boilers, furnaces, incinerators, water heaters or otherequipment using combustible or high temperature energy
sources. Pressure vessels. (Refer Note 1).

10.

Containers and their supporting structures for (Refer Note 1) :(a)
Toxic liquids and gases, spirits, acids, alkalis, molten metals or
uch dangerous materials.

6(b)Fire sprinkler systems including wet and dry risers

6

(c)

Other

4

11.

Switchgear, transformers, substations, electrical motor
control devices.

12.

Lighting fixtures :

13.

6

6

(a)

Rigidly mounted

2.5

(b)

Hanging or swinging type fixtures. (Refer Note 2)

3.5

Duct and piping distribution systems (Refer Note 1) :
(a)

(b)

Rigidly mounted -Flexible supports -(i)for toxic or dangerous substances

6

(ii)

other

3

(i)

for toxic or dangerous substances

8

(ii)

other

5

14.

Shelving for batteries and dangerous goods (Refer Note 4).

415.

Lift machinery, guides, etc.

3

16.

Emergency standby equipment required to function immediately after an
6earthquake.
(continued on next page)
Table 12.1 continued

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25
Table 12.1 continued
NOTES :
1.

The seismic weight of containers and the like shall include the weight of the contents.

2.

Hanging or swinging lights shall have a safety cable attached to the structure and the
fixture, capable of supporting a lateral load equal to four times the weight.

3.

Where towers, chimneys or smoke stacks exceed 10 % of the weight of the structure, thestructure shall be analyzed considering these elements.

4.

Shelving in Item 14 shall provide positive restraint to horizontal movement of the contents.

5.

Suspended Ceilings :Suspended ceilings with tiles weighing more than 2 kg shall satisfy the following
requirements :(a)

The support systems for suspended ceilings shall be designed and constructed so as
the avoid sudden or incremental failure or excessive deformations that would
release ceiling components.

(b)

Ceiling elements and lighting fixtures or other heavy fittings built into the ceiling,
shall be positively anchored to their supports against a net upward force equal to
one-third their weight.

(c)

The ceiling shall be designed for the horizontal loads in Item 4 with the support
members positively connected to each other and to the building or other horizontal
restraint.

Ceilings in important areas (such as hospital operating rooms) where loss of ceiling units
cannot be tolerated, should be fixed rigidly and directly to the structure.
Ceilings with tiles weighing less than 2 kg need not be designed to these requirements.

12.6

Separation of Elements
12.6.1 Applicable Elements
The requirements of 12.6.2 for the separation of elements shall apply to thefollowing :(a)NBC105V2.RV5

Elements such as stairways, rigid partitions, and non-structural
masonry walls of part or full height.

10 May 1994

26
(b)

Flexible partitions not capable of altering the intended structural
behaviour but required to have a fire resistance rating, provided that
this need not apply when it can be shown that the partition retains its
fire resistance after being subjected to the specified deformation.

(c)Precast concrete cladding and other cladding of similar mass.

(d)

Glass windows and other rigid, brittle, exterior cladding.

Elements which can accept inter-storey deflections of four times those
calculated in accordance with 9 without being damaged and without affecting
the structure need not comply with the separation requirements of 12.6.2.
12.6.2 Separation Requirements
Requirements for the separation from the structure of elements listed in
12.6.2 shall be as follows :

13

(a)

Ratio of inter-storey deflection to storey height not exceeding 0.0012: No requirements for separation.

(b)

Ratios of inter-storey deflection to storey height exceeding 0.0012 but
not greater than 0.015 or 60 mm : Elements shall be positively
separated from the structure so as to allow the structure to deform as
calculated in accordance with 9 without the elements coming into
contact with the structure or with adjacent elements. A minimum
separation of 10 mm shall be maintained between the structure andthe vertical surfaces of the element. Construction tolerances shall not
reduce the required separations.

Structural Variations to be Approved by Designer
The structural designer shall make the builder or contractor aware of the dangers that canarise when structural elements or details are changed or varied without the specific approvalof the structural engineer. Any variations approved by the designer shall comply with therequirements of this Standard.

NBC105V2.RV5

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NEPAL NATIONAL BUILDING CODE
NBC 106 : 1994

SNOW LOAD

Government of Nepal
Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL
Reprinted : 2064

NBC 106VO.RV4

7 February 1994

NEPAL NATIONAL BUILDING CODE
NBC 106 : 1994

SNOW LOAD

This publication represents a standard of good practice andtherefore takes the form of recommendations. Compliance with it
does not confer immunity from relevant legal requirements,
including bylaws
tTsflng >L % sf] ;/sf/ -dlGqkl/ifb\_ sf] ldlt @)^).$.!@ sf] lg0f{ofg';f/ :jLs[tGovernment of Nepal
Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL
Reprinted : 2064

NBC 106VO.RV4

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i

PrefaceThis Nepal Standard was prepared during 1993 as part of a project to prepare a draft National Building
Code for Nepal.
In 1988 the Ministry of Housing and Physical Planning (MHPP), conscious of the growing needs of
Nepal's urban and shelter sectors, requested technical assistance from the United Nations Development
Programme and their executing agency, United Nations Centre for Human Settlements (UNCHS).
A programme of Policy and Technical Support was set up within the Ministry (UNDP Project
NEP/88/054) and a number of activities have been undertaken within this framework.
The 1988 earthquake in Nepal, and the resulting deaths and damage to both housing and schools, again
drew attention to the need for changes and improvement in current building construction and design
methods.
Until now, Nepal has not had any regulations or documents of its own setting out either requirements
or good practice for achieving satisfactory strength in buildings.
In late 1991 the MHPP and UNCHS requested proposals for the development of such regulations anddocuments from international organisations in response to terms of reference prepared by a panel ofexperts.
This document has been prepared by the subcontractor's team working within the Department of
Building, the team including members of the Department and the MHPP. As part of the proposedmanagement and implementation strategy, it has been prepared so as to conform with the general
presentation requirements of the Nepal Bureau of Standards and Metrology.
The subproject has been undertaken under the aegis of an Advisory Panel to the MHPP.

The Advisory Panel consisted of :Mr. UB Malla, Joint Secretary, MHPP
Director General, Department of Building(Mr. LR Upadhyay)
Mr. AR Pant, Under Secretary, MHPP
Director General, Department of Mines & Geology(Mr. PL Shrestha)
Director General, Nepal Bureau of Standards & Metrology(Mr. PB Manandhar)
Dean, Institute of Engineering, Tribhuvan University(Dr. SB Mathe)
Project Chief, Earthquake Areas Rehabilitation &Reconstruction Project
President, Nepal Engineers Association
Law Officer, MHPP (Mr. RB Dange)
Representative, Society of Consulting Architectural &Engineering Firms (SCAEF)

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ChairmanMemberMemberMemberMemberMemberMemberMemberMemberMember

7 February 1994

ii

Representative, Society of Nepalese Architects (SONA)
Deputy Director General, Department of Building,(Mr. JP Pradhan)

MemberMember-Secretary

The Subcontractor was BECA WORLEY INTERNATIONAL CONSULTANTS LTD. of New
Zealand in conjunction with subconsultants who included :Golder Associates Ltd., Canada
SILT Consultants P. Ltd., Nepal
TAEC Consult (P.) Ltd., Nepal
Urban Regional Research, USA

Principal inputs to this Standard came from :Mr. YK Parajuli, TAEC
Mr. AS Arya, Professor Emeritus, University of Rookee

Revisions and Updated to this code came from :Mr. Purna P. Kadariya, DG, DUDBC
Mr. Kishore Thapa, DDG DUDBC
Mr. Mani Ratna Tuladhar, Sr. Div. Engineer, DUDBC
Mr. Jyoti Prasad Pradhan, Ex. DDG, DOB
Mr. Bhubaneswor Lal Shrestha, Ex. DDG, DOB
Mr. Uttam Shrestha, Architect, Architects’ Module Pvt. Ltd.
Mr. Manohar Lal Rajbhandhari, Sr. Structural Engineer, MR Associates
Mr. Amrit Man Tuladhar, Civil Engineer, DUDBC

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iii

TABLE OF CONTENTS

Preface..................................................................................................................................................i0

Foreword....................................................................................................................................iv

1.

Scope............................................................................................................................................ 1

NEPAL AMENDMENTS TO IS: 874 (Part 4) –1987..................................................................... 1
0
Foreword................................................................................................................................. 1
1. ...................................................................................................................................................... 2
3............................................................................................................................................................ 2
4............................................................................................................................................................ 2
6............................................................................................................................................................ 2

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iv

0Foreword
This Nepal Standard on "Snow Load" comprises the Indian Standard IS: 875 (Part 4) 1987 :CODE OF PRACTICE FOR DESIGN LOADS (OTHER THAN EARTHQUAKE) FOR
BUILDINGS AND STRUCTURES (Second Revision) with amendments as set out herein.

These amendments have been necessary to ensure the requirements of Nepalese context.

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1

1.

Scope
NEPAL AMENDMENTS TO IS: 874 (Part 4) –1987

0Foreword
Delete 0.1 to 0.3.2 inclusively and replace with:
Most of the mountainous districts of Nepal experience snowfall two to three times a year.
The districts that experience snowfall are Darchula, Bajhang, Humla, Mugu, Jumla, Dolpa,
Rukum, Mustang, Manang, Gorkha, Rasuwa, Sindhupalchok, Dolakha, Solukhumbu,
Sankhuwasabha and Taplejung. The depth of snow that occurs in these places is variable.
The country can broadly be divided into five categories based on the physiographic regions.
Of these five physiographic regions, the Terai, the Siwaliks and the Middle Mountains do
not experience snowfall. The region falling in the high mountains, however, gets snow
during two or three months of a year. The High Himalayas always have snow coverthroughout the year. Figure 1.1 shows the regions of the country and the likelihood that eachwill experience snow.
During a study to produce an inventory of current building practices (as part of the National
Building Code Development Project), the teams gathered information pertaining to historicexperiences of snowfall in the locality of surveyed buildings. Based on owner's responses, aground snow load of about 1.2 m. was estimated for Jomsom. Jomsom is located at anelevation of about 2800 m. above mean sea level in the High Himalayas region.
At high altitudes and adjoining areas, flat roofs are built with mud placed over timber planks
or split pieces of wood. A slope is not provided because the wind speed is high and therainfall is sparse. According to the local people, on roofs with only a mild slope the mud
even gets eroded by rainfall of only moderate intensity. Only a nominal slope that is justenough to drain the melted snow and rain water is provided. Snow accumulates on the roof
and the narrow space between the adjacent buildings is also filled. Snow accumulated on theroof is removed manually.
Historical snow data in Nepal does not exist and is only recently being recorded. The Snowand Glacier Hydrology Project has started to collect data in the higher regions. Depth,
density and water equivalent are monitored. Readings are becoming available from theLangtang and some other regions of the country with glaciers. Stations close to humansettlements do not exist.
The project dispatches teams to the stations in February. The team spends one week
collecting the identified parameters. Typical information obtained from the project is given
in Table 1. The snow depth obtained from the project, however, is far less than that obtained
from verbal inquiry. For this reason, the concerned personnel and the institutions are being
requested to collect information from in-depth studies and inquiries of the knowledgeable
people of the locality and to make this information available for snow load derivation.

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2

In many parts of the snow-prone region, buildings using foreign materials (e.g., glass andcement pointing of the front walls) are being built. However, no roofs are constructed ofcorrugated iron sheet. Rice and wheat straw are not available and hence thatched roofs aretotally absent. No other alternative materials for roofing can be obtained in these regions
because the land in this area consists mainly of sand mounds where vegetation growth isvirtually nil. Human settlement in these regions is concentrated mainly on the river banks
which are shifting downwards because the stream bed consists of a sand bed which is
sharply cut by the water currents.
0.4
1.

1st line, delete "part" and substitute with "Code".

1st line, delete "part 4".
4th line, delete "in part 2 Imposed load".
Note, delete inclusively.

3.

Note, delete all except the last sentence.

4.
4.21

6.

Replace
Replace

0O < ß < = 30O with 0O < ß < 15O , and
0O < ß < = 30O with 15O < ß < 30O

Add new clause :6.1

Minimum Slope for Roof

6.1.1 For efficient removal of the snow, the minimum slope for a roof should be in theratio of 2:1 (V: H). Higher sloped roofs become better for snow. However, the caseis the reverse for wind. The most favorable slope for both wind and snow is therefore
about 2:1.
6.1.2 It is ironic that the areas which experience snowfall have flat roofs and the otherareas, which do not experience snow have sloped ones. The probable reasons forproviding a flat roof are the unavailability of suitable indigenous materials for asloped one and the possibility of the wind blowing away the roof. Imported
corrugated iron sheet is possibly the only realistic alternative. However, the intensityof wind and the economy of construction should be though of before a change tosloped roofs is suggested for traditional buildings.
6.1.3 The snow and Glacial Hydrology Project dispatches teams to the stations eachFebruary.The team spends one week collecting the identified parameters. The
information obtained from the project is given in Table 1.

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3

TABLE 1 : SUMMARY OF SNOW DEPTH/DENSITY IN LANGTANG AREA

Date

24/25-II-91
26-II-91
27-II-91

Location
Tsergoti
Yala PeaktoKyanging base
camp
Plateau # 1
near gauging

Slope

Mean
Depth ofSnow
(cm)

StandardDevi
ation of Snow

Number of
Observeations

Density(gm/cm3)

Water
Equivalent(mm)

5000 to4920

Varies

33.0

46.2

145

0.320

107.0

Density quite
variable

3900

SW

16.6

1.3

14

0.069

11.5

Just able to snow
fall

3700

W

16.9

2.5

15

0.11

19.0

Just after snow fall

W

15.4

0.8

10

0.134

21.0

15.7

1.5

10

0.126

20

Elevation(m)

27-II-91

Plateau # 2
near gauging

3760

27-II-91

Plateau # 3
near gauging

3820

27-II-91

Bottom of trail
toNayang
Khola

3880

N

34.3

3.5

15

0.123

42

27-II-91

Kyanging base
house

3900

SW

19.2

3.0

57

0.11

20

27-II-91

Kyanging base
house

3900

SW

16.7

3.3

12

0.11

18.5

Source : Snow and Glacier Hydrology Project

Remarks

One hour aftersnow strong
sunshine
Two hours aftersnow
Forest area, rough,shape, old snow,
depth hoar frostpresent
Estimated fromplateau # 1 justafter snow fall
Sub set of above
snow depth

4

SIMIKOTDARCHULACHAINPURBAITADI

MARTADI

DIPAYALDADELDHURA

40

JUMLA

0

80

40

SILGADHI

180 KM.

120

SCALE

MANGALSEN
MAHENDRANAGAR
DAILEKH

JOMSOM

JAJARKOTDHANGADHI

CHAME

BIRENDRANAGAR
SALYANLIBAN

BAGLUNGKUSMA

TULSIPURNEPALGUNJTAMGHASPYUTHANPOKHARADHUNCHESAGARMATHA( MT. EVEREST)GORKHASANDHIKHARKA

BIDUR
DHADINGBESIKATHMANDU
BUTWALSIDDHARTHANAGAR

CHAUTARABHAKTAPUR

BHARATPURLALITPUR

DHULIKHELPATASISALLETIHETAUDARAMECHHAPKHADBARI

OKHALDHUNGASINDHULIMADIDIKTELLEGEND
INTERNATIONAL BOUNDARYHEADQUARTERS
CAPITALREGIONAL
ZONE & TOWNPEAK & PASSHIGH HIMALAYA ( PER

SNOW)TAPLEJUNG
PHIDIMBHOJPURTEHRATHUM

BIRGUNJ
KALAIYAMIDDLE MOUNTIAN ( NO SNOW)J ANAKPUR

DHARANJ ANAKPUR
SIMARARAJBIRAJSIWALIK ( NO SNOW)TARAI ( NO SNOW)

Figure 1.1 PHYSIOGRAPHIC REGION SHOWING SNOWFALL AREAILAM

DHANKUTAHIGH MOUNTIAN ( OCCASIONAL SNOW)BHADRAPUR
BIRATNAGAR

NEPAL NATIONAL BUILDING CODE
NBC 107 : 1994PROVISIONAL RECOMMENDATION ON
FIRE SAFETY

Government of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC107V0.RV8

12 May 1994

NEPAL NATIONAL BUILDING CODE
NBC 107 : 1994PROVISIONAL RECOMMENDATION ON
FIRE SAFETY
This publication represents a standard of good practice and therefore
takes the form of recommendations. Compliance with it does not confer
immunity from relevant legal requirements, including bylaws
tTsflng >L % sf] ;/sf/ -dlGqkl/ifb\_ sf] ldlt @)^).$.!@ sf] lg0f{ofg';f/ :jLs[tGovernment of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC107V0.RV8

12 May 1994

i

PrefaceThis Nepal Standard was prepared during 1993 as part of a project to prepare a draft National Building
Code for Nepal.
In 1988 the Ministry of Housing and Physical Planning (MHPP), conscious of the growing needs of
Nepal's urban and shelter sectors, requested technical assistance from the United Nations Development
Programme and their executing agency, United Nations Centre for Human Settlements (UNCHS).
A programme of Policy and Technical Support was set up within the Ministry (UNDP Project
NEP/88/054) and a number of activities have been undertaken within this framework.
The 1988 earthquake in Nepal, and the resulting deaths and damage to both housing and schools, again
drew attention to the need for changes and improvement in current building construction and design
methods.
Until now, Nepal has not had any regulations or documents of its own setting out either requirements orgood practice for achieving satisfactory strength in buildings.
In late 1991 the MHPP and UNCHS requested proposals for the development of such regulations anddocuments from international organisations in response to terms of reference prepared by a panel ofexperts.
This document has been prepared by the subcontractor's team working within the Department of
Building, the team including members of the Department and the MHPP. As part of the proposedmanagement and implementation strategy, it has been prepared so as to conform with the general
presentation requirements of the Nepal Bureau of Standards and Metrology.
The subproject has been undertaken under the aegis of an Advisory Panel to the MHPP.
The Advisory Panel consisted of :Mr. UB Malla, Joint Secretary, MHPP
Director General, Department of Building(Mr. LR Upadhyay)
Mr. AR Pant, Under Secretary, MHPP
Director General, Department of Mines & Geology(Mr. PL Shrestha)
Director General, Nepal Bureau of Standards & Metrology(Mr. PB Manandhar)
Dean, Institute of Engineering, Tribhuvan University(Dr. SB Mathe)
Project Chief, Earthquake Areas Rehabilitation &Reconstruction Project
President, Nepal Engineers Association
Law Officer, MHPP (Mr. RB Dange)
Representative, Society of Consulting Architectural &Engineering Firms (SCAEF)
Representative, Society of Nepalese Architects (SONA)
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ChairmanMemberMemberMemberMemberMemberMemberMemberMemberMemberMember
12 May 1994

ii

Deputy Director General, Department of Building,(Mr. JP Pradhan)

Member-Secretary

The Subcontractor was BECA WORLEY INTERNATIONAL CONSULTANTS LTD. of New
Zealand in conjunction with subconsultants who included :Golder Associates Ltd., Canada
SILT Consultants P. Ltd., Nepal
TAEC Consult (P.) Ltd., Nepal
Urban Regional Research, USA

Principal inputs to this Standard came from :Mr. YK Parajuli, TAEC
Mr. JR Pokharel, TAEC

Revisions and Updated to this code came from :Mr. Purna P. Kadariya, DG, DUDBC
Mr. Kishore Thapa, DDG DUDBC
Mr. Mani Ratna Tuladhar, Sr. Div. Engineer, DUDBC
Mr. Jyoti Prasad Pradhan, Ex. DDG, DOB
Mr. Bhubaneswor Lal Shrestha, Ex. DDG, DOB
Mr. Uttam Shrestha, Architect, Architects’ Module Pvt. Ltd.
Mr. Manohar Lal Rajbhandhari, Sr. Structural Engineer, MR Associates
Mr. Amrit Man Tuladhar, Civil Engineer, DUDBC

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TABLE OF CONTENTS

Preface ......................................................................................................................................................... i0

Foreword ....................................................................................................................................... iv

1

Scope .............................................................................................................................................. 1

2

Interpretation ............................................................................................................................... 1
2.1
2.2

3

General.............................................................................................................................. 1
Terminology ..................................................................................................................... 1

Types of Construction and Appliances ..................................................................................... 1
3.1
3.2

Fire Places......................................................................................................................... 1
Fire Extinguishers ........................................................................................................... 24Fire Zones...................................................................................................................................... 2

5

General Requirements................................................................................................................. 2
5.1
5.2
5.3
5.4

6

Provision of a Proper Access.......................................................................................... 2
Provision of Wide Doors................................................................................................. 2
Provision of Fire Escape Ways ...................................................................................... 2
Provision of Open Space................................................................................................. 2

Exit Requirements........................................................................................................................ 3
6.1
6.2

General Requirements.................................................................................................... 3
Number of Exits............................................................................................................... 3
6.2.1 Stairs ........................................................................................................................ 3
6.2.2 Fire Escapes ............................................................................................................ 3
6.2.3 Exit Doors................................................................................................................ 3

7

Access to a Building ..................................................................................................................... 4

8

Lightning Arresters/Conductors................................................................................................ 4

9

References ..................................................................................................................................... 4

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0.

Foreword
0.1

This Standard covers the basic requirements for fire safety in the design of ordinary
buildings.

0.2This Standard, with due consideration to the severe limitations on the issue of fire
protection in Nepali conditions, takes a modest approach. It deals only with theminimum requirements of exits from and access to ordinary residential buildings fromthe fire safety point of view. Designers are encouraged, wherever possible, toincorporate higher levels of fire safety in their designs by following other relevant
reference, Standards or Codes.

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1

Scope
1.1

2

This Standard provides fundamental requirements for fire safety in ordinary buildings.
These requirements do not necessarily cover the fire safety provisions needed for otherbuildings. For the design of such other buildings, other relevant Codes and Standards
which might be followed have been suggested.

Interpretation
2.1

2.2

General
2.1.1

In this Standard the word "shall" indicates a requirement that is to be adopted inorder to comply with the Standard, while the word "should" indicatesrecommended practice.

2.1.2

Commentary clauses are prefaced by the letter C and the number of theappropriate clause subject to comment.

2.1.3

Words implying the singular also include the plural and vice-versa where thecontext requires it.

Terminology
For the purpose of this Standard, the following definitions shall apply, unlessinconsistent with the context :IMPORTANT BUILDINGS means those buildings which either house facilities
essential before and after disaster (eg, hospitals, fire and police stations, communication
centres, etc), or which by their very purpose have to house several persons at one time(eg, cinema halls, schools, convention centres, etc), or will have national andinternational importance (eg, palaces, etc), or which house hazardous facilities (eg, toxic
or explosive facilities, etc).
ORDINARY BUILDINGS are the buildings, which do not come under the category ofimportant buildings. They include commercial and office buildings.

3

Types of Construction and Appliances
3.1

Fire Places
All buildings having a kitchen should be provided with a fireplace and a chimney inorder to reduce the possibilities of the occurrence of accidental fire. Open hearths
should be discouraged and eliminated wherever possible. Timber construction should
not be placed near the fire place, nor should it remain exposed in the vicinity of fire.
Such surfaces should remain encased by plaster, whether of mud or other binders,suitable for the purpose.

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3.2

Fire Extinguishers
Occupants are encouraged to install appropriate portable fire extinguishers in theirbuilding.
Where open hearth or kerosene stoves are used for cooking, sufficient water should be
stored in containers for emergency use in case of fire.

4

Fire Zones
In urban areas, the demarcation of fire zones should be carried out in consultation with therelevant municipal authority as and when deemed necessary.
These shall conform to the requirements specified by the Department of Urban
Development and Building Construction or any other agency responsible for developing anddemarcating such fire zones.

5

General Requirements
All buildings shall be designed in such a way that they can contribute to the containment of afire and thus reduce its spread to other buildings.
5.1

Provision of a Proper Access
Every building should have an access as defined by Architectural Design
Requirements (NBC 206) and should be wide enouth to enable the fireman to easily
approach to the building site.

5.2

Provision of Wide Doors
The entry door shall be as defined by Architectural Design Requirements (NBC 206)and should be sufficiently wide and tall so that easy access in available to the fire man.

5.3

Provision of Fire Escape WaysAll buildings should have sufficient ways as defined by Architectural Design
Requirements (NBC 206) so as to allow the rapid evacuation of all occupants in theevent of fire, if any. In addition to the main entrance, the side and/or rear entrance shallbe incorporated in the design.
The set back and/ or open space shall conform to the planning and building by-laws
adopted by the concerned and authorized territorial authority.

5.4

Provision of Open Space
The front entrance should have enough open space as defined by Architectural Design
Requirements (NBC 206) so that a number of people can gather and contribute in
extinguishing the fire, if any.

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6

Exit Requirements
6.1

General Requirements
An exit normally shall consist of either a doorway, corridor or passageway to aninternal staircase, to an external staircase, to a verandah leading to the street, to the roofof a building, or to the street. The exit may also lead to another building in theneighbourhood. The exit should :

6.2

a)

be able to allow the evacuation of all the occupants in a relatively short time;b)meet the minimum requirements as to size;c)

be free of any obstructions and shall not provide any resistance to movement;d)be clearly visible, preferably with proper signs;e)be continuous and shall not intrude into private space.

Number of Exits
6.2.1

StairsThe number of stairs in any building, especially when it exceeds 500 square
metres in plinth area, shall be a minimum of two, one internal and the other anexternal fire escape. Additional stairs shall be provided in proportion to any
increase in the plinth area.
In the case of residential buildings, the minimum width of the stairs shall be 90
cm. For other buildings, the minimum width shall be 1.5 m. The distance fromany point in a passageway to a staircase in a building shall not exceed 20
metres.

6.2.2

Fire Escapes
Every building more than five storeys high shall have a separate fire escapehaving a minimum width of 75 cm. The fire escape shall have a minimum tread
width of 20 cm and each riser shall be not more than 19 cm high. The numberof risers per flight shall not be more than 15. Such a fire escape shall carry users
towards an open space.

6.2.3

Exit Doors
Exit doors shall open to a passageway or to a corridor.
They should open outwards, but without restricting the movement of people
passing outside the door.
The maximum distance of such an exit doorway from any point in a passage
shall be 20 m.
The exit doorway shall neither be smaller than 90 cm in width, nor 180 cm inheight.

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7

Access to a Building
It shall comply with all applicable zoning requirements and by-laws of the local planning andbuilding authority.
The access leading to a building should preferably be by a road at least four metres wide, andno such road should lead to a dead end. The road should not have such sharp or restricted turns
that the passage of a fire engine is made difficult in the event of fire.

8

Lightning Arresters/Conductors
There have been many incidents in Nepal when lightning strikes have resulted in fire inbuildings and a consequential loss of life and property. The need to install lightning
arresters/conductors is therefore important.
A lightning arrester shall be located in the highest part of every building and it shall beconnected by a conductor to an earth rod buried in the earth. The lightning arrester shall be solocated that as much as possible of the building lies inside the surface of an imaginary cone
having a vertex angle of 45 degrees and its apex at the top of the arrester.

9

Referances

NBC107V0.RV8

National Building Code of India 1983, Part IV, Bureau of Indian Standards, New Delhi.

United Building Code (UBC), Part VII, Chapters 33 & 37, USA.

MV Lisitsyan and EC Pronin, "Architectural Design for Dwelling Houses", Moscow,
1990 (available in Russian and English).

12 May 1994

NEPAL NATIONAL BUILDING CODE
NBC 108 : 1994

SITE CONSIDERATION FOR SEISMIC HAZARDS

Government of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC108V2.RV9

7 December 1993

NEPAL NATIONAL BUILDING CODE
NBC 108 : 1994

SITE CONSIDERATION FOR SEISMIC HAZARDSThis publication represents a standard of good practice and therefore
takes the form of recommendations. Compliance with it does not confer
immunity from relevant legal requirements, including bylaws
tTsflng >L % sf] ;/sf/ -dlGqkl/ifb\_ sf] ldlt @)^).$.!@ sf] lg0f{ofg';f/ :jLs[tGovernment of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC108V2.RV9

7 December 1993

i
PrefaceThis Nepal Standard was prepared during 1993 as part of a project to prepare a National Building Codefor Nepal.
In 1988 the Ministry of Housing and Physical Planning (MHPP), conscious of the growing needs of
Nepal's urban and shelter sectors, requested technical assistance from the United Nations Development
Programme and their executing agency, United Nations Centre for Human Settlements (UNCHS).
A programme of Policy and Technical Support was set up within the Ministry (UNDP Project
NEP/88/054) and a number of activities have been undertaken within this framework.
The 1988 earthquake in Nepal, and the resulting deaths and damage to both housing and schools, again
drew attention to the need for changes and improvement in current building construction and design
methods.
Until now, Nepal has not had any regulations or documents of its own setting out either requirements orgood practice for achieving satisfactory strength in buildings.
In late 1991 the MHPP and UNCHS requested proposals for the development of such regulations anddocuments from international organisations in response to terms of reference prepared by a panel ofexperts.
This document has been prepared by the subcontractor's team working within the Department of
Building, the team including members of the Department and the MHPP. As part of the proposedmanagement and implementation strategy, it has been prepared so as to conform with the general
presentation requirements of the Nepal Bureau of Standards and Metrology.
The subproject has been undertaken under the aegis of an Advisory Panel to the MHPP.
The Advisory Panel consisted of :Mr. UB Malla, Joint Secretary, MHPP
Director General, Department of Building(Mr. LR Upadhyay)
Mr. AR Pant, Under Secretary, MHPP
Director General, Department of Mines & Geology(Mr. PL Shrestha)
Director General, Nepal Bureau of Standards & Metrology(Mr. PB Manandhar)
Dean, Institute of Engineering, Tribhuvan University(Dr. SB Mathe)
Project Chief, Earthquake Areas Rehabilitation &Reconstruction Project
President, Nepal Engineers Association
Law Officer, MHPP (Mr. RB Dange)
Representative, Society of Consulting Architectural &Engineering Firms (SCAEF)

NBC108V2.RV9

ChairmanMemberMemberMemberMemberMemberMemberMemberMemberMember

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ii
Representative, Society of Nepalese Architects (SONA)
Deputy Director General, Department of Building,(Mr. JP Pradhan)

MemberMember-Secretary

The Subcontractor was BECA WORLEY INTERNATIONAL CONSULTANTS LTD. of New
Zealand in conjunction with subconsultants who included :Golder Associates Ltd., Canada
SILT Consultants P. Ltd., Nepal
TAEC Consult (P.) Ltd., Nepal
Urban Regional Research, USA

Principal inputs to this standard came from :Mr. AM Dixit, SILT
Mr. YK Parajuli, TAEC
Mr. JK Bothara, TAEC
Mr. AM Tuladhar, DoB, HMGN
Dr. RD Sharpe, BECA (Team Leader)

Revisions and Updated to this code came from :Mr. Purna P. Kadariya, DG, DUDBC
Mr. Kishore Thapa, DDG, DUDBC
Mr. Mani Ratna Tuladhar, Sr. DIV. Engineer, DUDBC
Mr. Jyoti Prasad Pradhan, Ex.DG, DOB
Mr. Bhubaneswor Lal Shrestha, Ex. DDG, DOB
Mr. Uttam Shrestha, Architect, Architects' Module Pvt. Ltd.
Mr. Manohar Lal Rajbhandhari, Sr. Structural Engineer, Mr Associates
Mr. Amrit Man Tuladhar, Civil Engineer, DUDBC

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TABLE OF CONTENTS

Preface ........................................................................................................................................................... i0

Foreword ........................................................................................................................................ iv

1

Scope ................................................................................................................................................. 1
1.1 Applicability .......................................................................................................................... 1

2

Interpretation .................................................................................................................................. 1
2.1 General................................................................................................................................... 1
2.2 Terminology .......................................................................................................................... 1

3

Site Considerations ......................................................................................................................... 3
3.1 Consideration of Potential Fault Rupture Hazard .......................................................... 3
3.2 Consideration of Potential Liquefaction............................................................................ 4
3.3 Consideration of Potential Landslides and Slope Instability.......................................... 6

4

Site Investigation............................................................................................................................ 8
4.1
4.2
4.3
4.4

5

General................................................................................................................................... 8
Extent of Site Exploration ................................................................................................... 8
Depth of Exploration............................................................................................................ 8
Allowable Bearing Pressure ................................................................................................ 9

Design of Foundations................................................................................................................... 9

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0Foreword
This document sets out some of the factors to be considered during site selection for buildings
in order to minimise the risks to the buildings from both primary and secondary seismic
hazards.
It also outlines the fundamental requirements for site investigation for the foundation design ofbuildings.
The degree to which each factor should be considered will depend on the importance and sizeof the building under consideration. The document is particularly applicable for State of Art
Design and Engineered buildings.

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1

Scope
This standard covers the principles of site selection and site investigation for buildings in boththe mountainous and Terai regions of Nepal.
Conceptual and detailed aspects of the selection and design of building and foundation types are
not dealt with by this Standard, although recommended references are given for good practicein these matters.
1.1

Applicability
In general, the provisions of this standard should be applied to all buildings to beconstructed in Nepal.
The site considerations detailed out in this Standard shall be mandatory for all importantbuildings in Nepal.

The State of Art Design and engineered buildings of all categories should carry an appropriate
level of site investigation and formal reporting at the beginning of the design process and it
shall be incorportated in the permit application documents.
Subject to the mandatory rules-of-thumb and/or advisory guidelines the designer should
considered it as an indication of good practice and apply same as appropriate.
2Interpretation
2.1

2.2

General
2.1.1

In this standard the word "shall" indicates a requirement that is to be adopted inorder to comply with the standard, while the word "should" indicatesrecommended practice.

2.1.2

Words implying the singular only also include the plural unless this isinconsistent with the context.

Terminology
In this standard, unless inconsistent with the context, the following definitions shallapply :BEARING PRESSURE, SAFE means the intensity of the loading that the soil will
carry without undergoing settlement more than permissible for the structure.
CLAY means a type of soil with more than 50 % of the constituent particles smaller
than 2 µm. It is plastic within a moderate range of water content.

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CLAY, FIRM means a clay which at its natural water content can be moulded bysubstantial pressure with the fingers and can be excavated with a spade.
CLAY, SOFT means a clay which at its natural water content can be easily mouldedwith the fingers and can be readily excavated.
CLAY, STIFF means a clay which at its natural water content can not be moulded bysubstantial pressure with the fingers and requires a pick for its removal from the parent
body.
ENGINEERED BUILDING means any building designed in accordance with theengineered structures provisions of the Nepal National Building Code.
FOUNDATION means that part of the structure which is in direct contact with the soil
and transmits load to it.
FOUNDATION SOIL means the soil at the sub-surface which is in direct contact withthe foundation and bears the load due to the structure.
FROST ACTION means the weathering process caused by repeated cycles of freezing
and thawing.
GRAVEL means a cohesionless soil with more than 50 % of the constituent particles
having size greater than 4.75 mm and less than 80 mm.
HAZARD means the probability of occurrence of a destructing phenomena.
IMPORTANT BUILDINGS are those which :contain critical facilities which are essential before and immediately after adisaster (eg, hospitals, fire and police stations, communication centres etc),by their very purpose have to house many persons at a time (eg, cinema halls,
schools, convention centres, etc),have national and international importance (eg, historical palaces, monuments,
etc),



are to be used for storage of toxic or explosive materials.

LANDSLIDE means the downward and outward movement of slope-forming
materials.
LIQUEFACTION means the phenomenon exhibiited when relatively loose, saturated
sandy soils lose a large proportion of their strength under seismic shaking.

ORDINARY BUILDING is one which is not an important building (eg, a residential,
general commercial or ordinary office building, etc)
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ROCK MASS means those naturally occurring mineral aggregates in-situ with all theirplanes of discontinuities.
ROCK MATERIAL means a piece of rock detached from the rock mass and boundedby natural planes of discontinuities or induced fractures.
SAND means a cohesionless soil with more than 50 % of its constituent particles having
a size greater than 75 µm and less than 4.75 mm.
SAND, COARSE means a cohesionless soil with 50 % or more of its constituent
particles having a size greater than 2 mm and less than 4.75 mm.
SAND, FINE means a cohesionless soil with 50 % or more of its constituent particles
having a size greater than 75 µm and less than 0.425 mm.
SAND, MEDIUM means a cohesionless soil with 50% or more of its constituent
particles having a size greater than 0.425 mm and less than 2.0 mm.
SILT means a fine-grained soil with 50 % or more of its constituent particles having asize greater than 0.2 µm and less than 75 µm.
SOIL means a mineral aggregate or product of rock weathering lying at the place offormation or deposited after being transported by different natural means oftransportation.
SOIL, COARSE GRAINED means a soil with more than 50 % of its materials grains
larger than 0.75 µm.
SOIL, FINE GRAINED means a soil with more than 50 % of its material grains
smaller than 0.75 µm.
TERAI means the predominant alluvial plain to the south of the Siwalik range. This is
one of the five physiographic divisions of Nepal.
WATER TABLE means the locus of points in soil water at which the pressure is equal
to atmospheric pressure.
WEATHERING means the group of processes, such as the chemical action of air andrain water and of plants and bacteria and the mechanical action of changes oftemperature, whereby rocks on exposure to the weather change in character, decay, andfinally crumble into soil.
3

Site Considerations
3.1

Consideration of Potential Fault Rupture Hazard
A surface fault rupture occurs when an earthquake fault breaks the earth's surface and it
may result in several centimetres to several metres of differential ground

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displacement. This instantaneous ground displacement may occur along anapproximately linear path that may extend for several tens of kilometres. If the fault
traverses houses, buildings or infrastructures and lifelines, it may damage or destroy thefacilities.

Therefore, while selecting the site for an important building or structure, it shall beensured that the building is not located within a distance of 500 m from the surface traceof a known active fault.
Figure 3.1 depicts the principal active faults so far identified within Nepal and can bereferenced for this purpose.

Areas closer than 500 m to the trace of an active fault should be used for activities
unlikely to be severely affected by surface faulting. These include use as grassland,
forest, gardens, parks, etc.
3.2

Consideration of Potential Liquefaction
Liquefaction of subsurface soil occurs when groundwater saturated, loose, granular soil
is exposed to strong earthquake shaking for a relatively long duration. It commonly
results in sand boils, fissuring of the ground, settlement of the ground surface and lateral
spreading of the ground surface. These phenomena can cause different forms ofdamage to structures and properties lying across the soil failure areas.

The plains of the eastern Terai experienced wide-spread occurences of liquefaction
during the Bihar-Nepal earthquake of 1934 and the Udaypur earthquake of 1988.
Substantial damage resulted from this process. The most significant and spectacular of
the phenomenon was the generation of numerous sand craters and upwelling of water intube wells and dug wells.

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The site selection for an important engineered building in the Terai and on alluvial riverbanks within the mountainous terrain shall be preceded by examination of theliquefaction susceptibility of the sub-surface ground. Necessary mitigation measures
should be taken to minimise the potential risk. Sites located on ancient lake deposits(the Kathmandu Valley, for instance), shall be similarly investigated.
3.3

Consideration of Potential Landslides and Slope Instability
Earthquake-induced landslides can occur due to the strong ground shaking caused by anearthquake. All major earthquakes in mountainous terrain result in increased instancesof landslides. The vast majority of these are rock falls, although more coherent
landslides, such as debris slides and soil slumps, also take place.
Clearly, areas that are susceptible to landslides from storm damage, river undercutting
and quarrying are also susceptible to strong ground shaking from an earthquake.
Buildings may be destroyed by landslides because they are located on the body of thelandslide body, or by the impact and covering of the building by debris derived from alandslide generated uphill from the site. The building and associated earthworks may
also contribute to the instability of potential landslides.
Locating an important building on sloping ground in the mountainous terrain should be
preceded by examination of the hill slope stability conditions and identification ofnecessary structures for counteracting the effects of the adverse conditions.
On a sloping ground, the location of all buildings should meet the requirements shownin Figure 3.2, unless special slope stability measures are taken.

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Figure 3.2

LOCATION OF BUILDING IN SLPING TERRAIN

Face offooting
Top ofslope

Toe ofslope

HFace of structure
H/3 But need notexceed 40' max.

H/2 but need not exceed 15' max.

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4

Site Investigation
4.1

GeneralAll site investigations should address the following basic questions :Is there any danger of inherent natural susceptibility of the land to the processof sliding and erosion?

Will the construction adversely affect the existing conditions and trigger
landslide, erosion, land subsidence, pore pressure generation due to blockage ofor otherwise the sub-surface flow of water; will the construction adversely affectthe water table?

What will be the extent of settlement of the building?

Is the sub-surface capable of taking the load due to the proposed construction?

Is there any other natural/geological process likely to threaten the integrity ofthe building? (eg, changes in a river course, flooding, failure of an irrigation
canal ?)



What are the possible engineering solutions for ensuring stability of the building
foundation in view of the identified conditions?

Answers to some of these questions can be found by examining the existing local
knowledge, records of any past exploration in the adjacent area and the behaviour ofexisting similar structures. If satisfactory answers to the questions can not be found, it
will be necessary to undertake additional site investigation including subsurface
exploration, in-situ and laboratory testing, geophysical surveys and testing, probing, etc.
4.2

Extent of Site Exploration
The extent of exploration will depend upon the geological and geomorphological natureof the terrain, and on the importance of the building and the scale of the project. Largescale engineering geological mapping of the site and previous practices of constructionin the adjacent area could form the basis for deciding the extent of exploration for an
important building.

4.3

Depth of Exploration
The depth to be explored should be adopted based on the geological conditions at thesite eg the depth and type of subsurface soil, depth of weathering, the depth of groundwater fluctuation, the depth of frost action, etc. Generally, the exploration should be
carried out to the depths at which the induced stress due to the loads from theconstruction dissipates substantially and the strata can carry the load without
undesirable settlement and with an acceptable factor of safety against failure. Past
experience and performance of adjacent buildings could be of prime importance inNBC108V2.RV9

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9
deciding about the depth of exploration which shall not be less than one and a half times
the estimated width or the lower dimension of the footing below the foundation level.
In hilly areas, exploration up to the depth of sound bed rock will generally be sufficient.
For the analysis of liquefaction susceptibility, 20 m should suffice as the depth of
exploration.
4.4

Allowable Bearing Pressure
The allowable bearing pressure should be calculated as per current good engineering
practice.

5.

Design of Foundations
The design of foundations shall be carried out in accordance with good engineering practice.
Compliance with the following established codes/standards may be taken as the basis of goodengineering practice :NBC108V2.RV9

7 December 1993

10

The following Indian Standards :INDIAN STANDARDSINDIAN STANDARDS(1) IS :1892-1979 Method of practice for subsurface investigation for foundations (firstrevision)

IS:2720 (Part II)-1973 Part II
Determination of water content (second
revision)

IS:2131-1981 Method for standard
penetration test for soils (first revision)

IS:2720 (Part III)-1980 Part III
Determination of specific gravity :Section 1 Fine grained soils (firstrevision)
Section 2 Fine, medium and coarse
grained soils (first revision)

IS:2132-1972 Code of practice for thinwalled tube sampling of soils (first revision)
IS:4434-1978 Code of practice for insitu
vane shear test for soils (first revision)

IS:2720 (Part IV)-1975 Part IV Grainsize analysis (first revision)

IS:4968 Method for subsurface sounding forsoils :
IS:4968 (Part I)-1976 Part I Dynamic
method using 50 mm cone without
bentonite slurry (first revision)
IS:4968 (Part II)-1976 Part II Dynamic
method using cone and bentonite slurry(first revision)
IS:4968 (Part III)-1976 Part III Staticcone penetration test (first revision)
IS:8763-1978 Code of practiceundisturbed sampling of sandsfor

IS:9214-1979 Method of determination ofmodules of subgrade reaction (K-value) of
soils in field(2) IS:2720 Methods of tests for soils:
IS:2720 (Part I)-1972 Part I Preparationof dry soil samples for various tests (firstrevision)

IS:2720 (Part V)-1970 Part V
Determination of liquid and plastic limits(first revision)
IS:2720 (Part X)-1973 Part X
Determinationof
unconfinedcompressive strength (first revision)
IS:2720 (Part XIII)-1972 Part XIII Direct
shear test (first revision)
IS:2720 (PartDetermination
properties

XV)-1965 Part XVofconsolidation

IS:2720 (Part XXVIII)-1974 PartXXVIII Determination of dry density ofsoils in place by the sand replacement
method (first revision)
IS:2720 (Part XXIX)-1975 Part XXIX
Determination of dry density of soils inplace by the core cutter method (firstrevision)

contd.../

NBC108V2.RV9

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11

INDIAN STANDARDSINDIAN STANDARDS

IS:2720 (Part XXXIII)-1975 Part XXXIII
Determination of the density in-place by
the ring and water replacement method

IS:2911 (Part 1/Sec 1)-1979 Concrete
piles Section 1 Driven cast in-situ piles(first revision)

IS:2720 (Part XXXIV)-1972 PartXXXIV Determination of density of soils
in-place by rubber-balloon method

IS:2911 (Part I/Sec 2)-1979 Concrete
piles Section Bored cast insitu piles (firstrevision)

IS :2720 (Part XXXIX/Sec1)-1977 PartXXXIX Direct shear test for soils
containing gravel, Section 1 Laboratorytest(3) IS:1498-1970 Classification andidentification on soils for generalengineering purposes (first revision)(4) IS:401-1982 Code of practice forpreservation of timber (third revision)(5) IS:6403-1981 Code of practice fordetermination of allowable bearing pressure
on shallow foundations (first revision)(6) IS:1888-1982 Method of load tests on soils(second revision)(7) IS:8009 (Part I)-1976 Code of practice forcalculation of settlement of foundations:
Part I Shallow foundations subjected tosymmetrical static vertical loads(8) IS:1080-1980 Code of practice for designand construction of simple spreadfoundations (first revision)(9) IS:2911 (Part IV)-1979 Code of practice fordesign and construction of pile foundations: Part IV Load test on piles Section Boredcast in-situ piles(10) IS :2911 Code of practice for design andconstruction of pile foundations.

(11) IS:2911 (Part 1/Sec 3)-1979 Code ofpractice for design and construction of pilefoundations: Part I Concrete piles, Section
3 Driven precast piles (first revision)(12) IS:2911 (Part III)-1980 Code of practice fordesign and construction of pile foundations:
Part III Under-reamed pile foundation (firstrevision)(13) IS :2911 (Part III)-1980 Code or practicefor design and construction of pilefoundations: Part II Timber piles (firstrevision)(14) IS:2974 Code of practice for design andconstruction of machine foundations
IS:2974 (Part I)-1969 Part I Foundations
for reciprocating type machine (firstrevision)
IS:2974 (Part II)-1966 Part II
Foundations for impact type foundations(drop and forge hammer foundations)
IS:2974 (Part III)-1975 Part III
Foundations for rotary type machines(medium and high frequency) (firstrevision)
IS:2974 (Part IV)-1968 Part IV
Foundations for rotary type machines oflow frequency

contd.../

NBC108V2.RV9

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12

INDIAN STANDARDSINDIAN STANDARDS

IS:2974 (Part V)-1970 Part V
IS:9556-1983 Code of practice for design
Foundations for impact type machinesand construction of diaphragm walls
other than hammers (forging andstamping press: pig breaker, elevator and (15) IS:9214-1979 Method of determination ofhoist tower)
subgrade reaction (K value) of soils in thefield
IS:3955-1967 Code of practice for designand construction of well foundations

NBC108V2.RV9

7 December 1993

NEPAL NATIONAL BUILDING CODE
NBC 109 : 1994

MASONRY : UNREINFORCED

Government of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC108V2.RV9

7 December 1993

NEPAL NATIONAL BUILDING CODE
NBC 109 : 1994

MASONRY : UNREINFORCED
This publication represents a standard of good practice and therefore
takes the form of recommendations. Compliance with it does not confer
immunity from relevant legal requirements, including bylaws
tTsflng >L % sf] ;/sf/ -dlGqkl/ifb\_ sf] ldlt @)^).$.!@ sf] lg0f{ofg';f/ :jLs[tGovernment of Nepal

Ministry of Physical Planning and Works
Department of Urban Development and Building Construction
Babar Mahal, Kathmandu, NEPAL

Reprinted : 2064

NBC108V2.RV9

7 December 1993

i

PrefaceThis Nepal Standard was prepared during 1993 as part of a project to prepare a National Building
Code for Nepal.
In 1988 the Ministry of Housing and Physical Planning (MHPP), conscious of the growing needs of
Nepal's urban and shelter sectors, requested technical assistance from the United Nations Development
Programme and their executing agency, United Nations Centre for Human Settlements (UNCHS).
A programme of Policy and Technical Support was set up within the Ministry (UNDP Project
NEP/88/054) and a number of activities have been undertaken within this framework.
The 1988 earthquake in Nepal, and the resulting deaths and damage to both housing and schools, again
drew attention to the need for changes and improvement in current building construction and design
methods.
Until now, Nepal has not had any regulations or documents of its own setting out either requirements
or good practice for achieving satisfactory strength in buildings.
In late 1991 the MHPP and UNCHS requested proposals for the development of such regulations anddocuments from international organisations in response to terms of reference prepared by a panel ofexperts.
This document has been prepared by the subcontractor's team working within the Department of
Building, the team including members of the Department and the MHPP. As part of the proposedmanagement and implementation strategy, it has been prepared so as to conform with the general
presentation requirements of the Nepal Bureau of Standards and Metrology.
The subproject has been undertaken under the aegis of an Advisory Panel to the MHPP.
The Advisory Panel consisted of :Mr. UB Malla, Joint Secretary, MHPP
Director General, Department of Building(Mr. LR Upadhyay)
Mr. AR Pant, Under Secretary, MHPP
Director General, Department of Mines & Geology(Mr. PL Shrestha)
Director General, Nepal Bureau of Standards & Metrology(Mr. PB Manandhar)
Dean, Institute of Engineering, Tribhuvan University(Dr. SB Mathe)
Project Chief, Earthquake Areas Rehabilitation &Reconstruction Project
President, Nepal Engineers Association
Law Officer, MHPP (Mr. RB Dange)
Representative, Society of Consulting Architectural &Engineering Firms (SCAEF)

NBC109V1.RV7

ChairmanMemberMemberMemberMemberMemberMemberMemberMemberMember

19 May 1994

ii

Representative, Society of Nepalese Architects (SONA)
Deputy Director General, Department of Building,(Mr. JP Pradhan)

MemberMember-Secretary

The Subcontractor was BECA WORLEY INTERNATIONAL CONSULTANTS LTD. of New
Zealand in conjunction with subconsultants who included :Golder Associates Ltd., Canada
SILT Consultants P. Ltd., Nepal
TAEC Consult (P.) Ltd., Nepal
Urban Regional Research, USA

Principal inputs to this standard came from :Mr. AM Tuladhar, DoB, HMGN
Dr. AS Arya, Professor Emeritus, University of Roorkee, India
Dr. RD Sharpe, BECA (Team Leader)

Revisions and Updated to this code came from :Mr. Purna P. Kadariya, DG, DUDBC
Mr. Kishore Thapa, DDG, DUDBC
Mr. Mani Ratna Tuladhar, Sr. DIV. Engineer, DUDBC
Mr. Jyoti Prasad Pradhan, Ex.DG, DOB
Mr. Bhubaneswor Lal Shrestha, Ex. DDG, DOB
Mr. Uttam Shrestha, Architect, Architects' Module Pvt. Ltd.
Mr. Manohar Lal Rajbhandhari, Sr. Structural Engineer, Mr Associates
Mr. Amrit Man Tuladhar, Civil Engineer, DUDBC

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iii

TABLE OF CONTENTS
Preface......................................................................................................................................................... i0

Foreword...................................................................................................................................... vii

0.1
0.2

Design Aspects Covered ....................................................................................... .......... .......... vii
Related Codes

1

Scope .............................................................................................................................................. 1
1.1
1.2
1.3

2

Interpretation ............................................................................................................................... 1
2.1
2.2
2.3

3

Area Cover ....................................................................................................................... 1
Limitation......................................................................................................................... 1
Provisions for Historical Buildings............................................................................... 1

General.............................................................................................................................. 1
Terminology..................................................................................................................... 1
Symbols............................................................................................................................. 2

Materials........................................................................................................................................ 3
3.1
3.2
3.3
3.4

Material Used................................................................................................................... 3
Masonry Unit ................................................................................................................... 3
Tolerances ........................................................................................................................ 4
Classification of Bricks and Brickwork ....................................................................... 5
3.4.1
3.4.2

3.5
4

First Class Brickwork........................................................................................ 5
Limitation ............................................................................................................ 5

Mortar............................................................................................................................... 5

General Construction and Design Requirements ................................................................... 7
4.1
4.2
4.3
4.4

General.............................................................................................................................. 7
Selection of Mortar ......................................................................................................... 7
Thickness of Walls .......................................................................................................... 7
Stability Requirements ................................................................................................... 8
4.4.1
4.4.2

4.5

Parapets and Compound Walls .................................................................................... 9
4.5.1
4.5.2

NBC109V1.RV7

Lateral Support .................................................................................................. 8
Adequate Lateral Support ................................................................................ 8

General........................... ..................................................................................... 9
Free-Standing Walls........................................................................................... 919 May 1994

iv

4.5.3
4.5.4
4.5.5
4.6
4.7

Load Bearing Masonry Elements........................................................ 9
Slenderness Ratio................................................................................... 9
Curtain Walls ....................................................... ....................................9

Structural Design ............................................................................................................ 9
Design Method................................................................................................................ 10
4.7.1
4.7.2
4.7.3

Design Procedures ................................................................................ 10
Design Loads ......................................................................................... 10
Design of Wall Footings ....................................................................... 10
4.7.3.1 Depth of Footing........................................... ............................10
4.7.3.2 Width of Footing .................. ................................................... 11

4.7.4 Permissible Compressive Stresses........... ............................................... 11
5

General Requirements ............................................................................................................... 12
5.1
5.2

Deforming and Cracking .............................................................................................. 12
Cutting and Chasing...................................................................................................... 125.2.1 Stretches of Masonry ............................................................................... 125.2.2 Horizontal Chases .................................................................................... 125.2.3 Vertical Chases ......................................................................................... 125.2.4 Masonry Directly Above A Recess......................................................... 12

5.3

Workmanship .................................................................................................................. 13
5.3.1 Bedding of Masonry Units ...................................................................................13
5.3.2 Bond ........................................................................................................................ 13

6

Special Considerations for Earthquake Resistance ................................................................ 13
6.1
6.2

Siting ................................................................................................................................. 13
General Concepts ............................................................................................................ 13
6.2.1 Categories of Buildings ........................................................................................ 13
6.2.2 Seismic Zoning....................................................................................................... 14
6.2.3 Importance of Building ........................................................................................ 14

7

Site Considerations ..................................................................................................................... 16
7.1
7.2
7.3
7.4
7.5

8

General............................................................................................................................. 16
General Considerations................................................................................................. 16
Site Investigation Requirements .................................................................................. 16
Allowable Bearing Pressure.......................................................................................... 17
Combination of Parameters.......................................................................................... 17

Openings in Walls ....................................................................................................................... 21

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v

9Masonry Bond ............................................................................................................................. 22
9.1

10

Vertical Joints between Perpendicular Walls ............................................................ 22

Horizontal Reinforcement in Walls.......................................................................................... 23
10.1

Horizontal Bands or Ring Beams ................................................................................ 23

11

Section of Bands or Ring Beams............................................................................................... 25

12

Dowels at Corners and Junctions ............................................................................................. 28

13

Vertical Reinforcement in Walls .............................................................................................. 31

14

Reinforcement Details for Hollow Block Masonry ................................................................ 33
14.1

15

Vertical Reinforcement .............................................................................................................. 34
15.1

16

Horizontal Band ............................................................................................................. 33

Infill Panels and Non Structural Walls............................................. ........................ 34

Wall Thickness and Spacing......................................................................................................36

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vii

0.

Foreword

0.1

Design Aspect Covered
This Code of Practice covers the structural design aspect of unreinforced masonry elements inthe buildings. It also deals with some aspect of earthquake-resistant design of buildings.
References to seismic zoning, seismic coefficients, important factors, structural performancefactors and performance coefficient are as per NBC 105-94 Seismic Design of Buildings in
Nepal.

0.2

Related Codes
This Code should be read in conjunction with the Indian Standard IS:1905-1987 Code ofPractice for Structural Use of Unreinforced Masonry (Third Revision).

NBC109V1.RV7

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1

1

Scope
1.1

CoverageThis is a Code of Practice for the Structural Design Aspects of Unreinforced Masonry
Buildings in Nepal.

1.2

Limitation
The recommendations of this Code of Practice do not cover walls constructed in mud
mortar and should not be used for such case.

1.3

Provisions for Historical Buildings
The provisions of this Code of Practice shall be construed as advisory when being
applied to the repair, alternations or additions necessary for the conservation,
preservation, restoration, rehabilitation, reconstruction or continued use of buildings ofhistorical, architectural, cultural or archaeological significance.

2

Interpretation
2.1

GeneralIn this Code of Practice the word "shall" indicates a requirement that is to be adopted inorder to comply with the Code of Practice, while the word "should" indicatesrecommended practice.

2.2

Terminology
BEDDED AREA means the area of surface of a masonry unit which is in contact withmortar in the plane of joint.
CORBEL means one or more courses of brick projecting from a wall (such as acornice), generally to form a support for wall plates, etc. A brick should not project
more than one quarter of its length beyond the next lower course.
DEFINITIONS : The terminoloty given in Indian Standard IS:1905-1987 in clauses
2.1 to 2.21.3 will apply, except as stated here below.
DIMENSION means the measured dimension of a designed item and, if used todescribe masonry units, means the nominal dimension.
INFILL PANEL means a wall framed on four sides by columns and beams andcontributing to shear resistance in the plane of the frame, but which is not designed toresist vertical loads other than its own weight.

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2

LATERAL SUPPORT means a masonry structure support which enables a masonryelement to resist lateral load and/or restrains the deflection of the masonry element at
the point of support.
MASONRY means an arrangement of masonry units which may be brick,rectangularised stone, ashlar or cement blocks laid to a bond and joined together withmortar.
MASONRY UNIT means an individual unit which is bonded to similar units with thehelp of mortar to form a masonry element such as a wall, column, pier, buttress, etc.,
and conforming to the Nepal Standard Brick Masonry NS: 1/2035.
PANEL WALL means an exterior non load-bearing wall in framed construction
wholly supported by beams and columns.
PARTITION WALL means an interior non load-bearing wall which is separated so as
not to be part of the seismic resisting structure.
PARTY WALL means a wall built on land belonging to two adjoining owners, it
being the joint property of both the owners.
SLENDERNESS RATIO means the ratio of effective height or effective length to theeffective thickness which ever is less.
SR

2.3

=

Slenderness Ratio=

Effective Height orEffective Thickness

Effective Length
Effective Thickness

Symbols
The following letters, symbols and abbreviation are used for the purposes of thissection and other symbols are specified at their respective places.

NBC109V1.RV7

AArea of sectionb

Breadth of masonry unit or shorter dimension of a rectangular column

DL

Dead loadE

Modulus of elasticityeEccentricity

fb

Basic compressive stressfc

Permissible compressive stressfdCompressive stress due to dead load

19 May 1994

3

3

fs

Permissible shear stressK

Stiffness of memberkaArea factor

kp

Shape modification factor

ks

Stress reduction factor

LL

Live loadlAxial load on a compression member

lefEffective length or spanmModular ratio

W

Total load

WL

Wind loadw

Uniform distributed load

wp

Breadth of crosswall, piers, or buttresses

Z

Modulus of section

Materials
3.1

Permissible Material
The materials used in masonry construction shall be in accordance with NBC 101-94
Marerial Specifications unless otherwise specified.

3.2

Masonry Unit
The specification and properties of the masonry shall conform to the Nepal Standard
Brick Masonry NS: 1/2035. Its size is given below :NBC109V1.RV7

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4

Dimensions of Nepal Standard Brick (mm)LengthBreadthHeightVerticalMortar Joint

Remark

240

115

57

10

For 10 mm mortar joint

Table 3.1 : Dimensions of a Nepal Standard Birck
Note : Length of Birck = 2 x Width of Birck + 1 Vertical Mortar Joint

3.3

Tolerances
Tolerance for First and Second Class bricks are as in given Tables 3.2. and 3.3

Individual Brick Size
(Nominal Dimensions) (mm)Length of 20 Bricks
(mm)

Class

LengthBreadthHeightMinimum

Maximum

A
A
A

240
-

115
-

57

4700
2240
1170

4860
2360
1270

Table 3.2 :Individual Brick Size And Length of 20 Bricks (Class A)

Individual Brick Size
(Nominal Dimensions) (mm)Class

LengthBreadthHeightMinimum

Maximum

B
B
B

240
-

115
-

57

4660
2200
1150

4880
2360
1270

Table 3.3 :NBC109V1.RV7

Length of 20 Bricks(mm)Individual Brick Size and Length of 20 Bricks (Class B)

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5

3.4

Classification of Bricks and Brickwork
3.4.1

First Class Brickwork
All the bricks used for masonry construction shall be thoroughly burnt, deepcherry red or copper in colour, regular in standard shape and size, free fromcracks, emit a clear ringing sound on tapping with a steel trowel and have acrushing strength as per the Nepal Standard Brick Masonry NS: 1/2035. A
brick shall not absorb more water than 15 % of its weight after 24 hours ofsoaking in water at normal temperatures. However, hand-made bricks withkeys may have water absorption up to 25 % of their weight. For first classbrickwork, the corresponding mortar types should be H1 and H2.

3.4.2

Limitation
Masonry units that have been previously used should not be re-used in brickwork or brickwork construction unless they have been thoroughly cleaned andshown to conform to the Nepal Standard Brick Masonry NS: 1/2035.

3.5

MortarMortar used in masonry construction shall, unless otherwise specified, conform to thespecification listed in NBC 101 – Material Specifications.
Some of the commonly-used mortars in Nepal and their mix proportions, along with
their strengths, are listed in Table 3.4.

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6

SerialNo.

*

Mix(by volume)

MinimumCompressive
Strength at
28 days(N/mm2)*MortarType

Cement

Lime

Sand

1

1

0 to 0.25 C

3

10.0

H1

2(a)
2(b)

1
1

0
0.5 C

4
4.5

7.5
6.0

H2
H2

3(a)
3(b)

1
1

0
1C

5
6

5.0
3.0

M1
M1

4(a)
4(b)
4(c)

1
1
0

0
2C
1A

6
9
2 to 3

3.0
2.0
2.0

M2
M2
M2

5(a)
5(b)

1
1

0
3C

8
12

0.7
0.7

L1
L1

6

0

1 B or C

2 to 3

0.5

L2

1 N/mm2 = 1 MPa = 10.2 kg/cm2

Table 3.4 : Mix Proportions and Strength of Commonly- Used Mortars for
Masonry
Notes :i)

The strength of mortar may vary appreciably depending on the angularity, grading andfineness of the sand. The quantity of sand in the mix may, therefore, be decreased
where found necessary to attain the desired strength.

ii)

A, B and C denote eminently hydraulic lime, semi-hydraulic lime and fat lime
respectively.

iii)

When using plain cement sand mortars [S. No. 2(a), 3(a), 4(a), and 5(a)], it is desirable
to include a plasticizer in the mix to improve workability.

iv)

For mortar to S. No. 6, if lime C is used, part of the sand should be replaced by some
pozzolanic materials (eg., burnt clay or fly ash), in order to obtain the requiredcompressive stress.

v)

In this table, the classification of mortars as types H1, H2, M1, M2, L1 or L2 has been
given for convenience of reference in design calculations, the letter H standing for highstrength, M for medium strength and L for low strength.

vi)

For mortar types H2, M1, and M2, although the compressive strength of composite

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7

mortars (that is, cement and lime mortars) is somewhat less than that of cement
mortars, the masonry strength may not be significantly affected.

4

General Construction and Design Requirements
4.1

GeneralThe porvisions in clause 4.1 to 4.7 of the Indian Standard IS:1905-1987 shall beapplicable for designing masonry structures. In addition, the following clauses will
also be equally applicable :4.2

Selection of Mortar
The requirements of a good mortar for masonry structure are workability, strength,water retentively and low drying shrinkage. Mortar strength in general should not begreater than that of the masonry unit. For commonly-used mortars conforming toTable 3.4, the optimum mortar mixes from a brick strength consideration are given in
Table 4.1.

Table 4.1 :4.3

Mortar Typebelow 5M2

5 to 14.9

M1

15 to 24.9

H2

25 or above

H1

Optimum Mortar Mixes For Maximum Masonry Strength with
Masonry Units of Various Strengths

Thickness of Wallsa)

NBC109V1.RV7

Masonry Unit Strength(N/mm2)The thickness of a load-bearing wall shall be sufficient at all points to ensurethat stresses due to the worst condition of loading for which the wall is designed
are within the safe limit. The thickness of non load-bearing walls shall be
sufficient to meet considerations of stability and strength against lateral forces.

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8

4.4

b)

The thickness used for design calculation shall be the actual thickness of themasonry, not the nominal thickness. The actual thickness shall be computed as
the sum of the average dimensions of the masonry units as specified in the
Nepal Standard Brick Masonry NS:1/2035, together with the specified joint
thickness. In masonry with raked joints, the thickness shall be reduced by thedepth of raking. However, if joints are raked to provide a key for subsequent
plastering and the mix of mortar for plastering is not weaker than the masonrymortar, raking may be ignored. Also, if the raking of joints is to be followedby flush-pointing using a mortar of the same or better strength, the raking may
be ignored.

c)

The thickness of a wall determined from strength considerations may not be
always sufficient to satisfy requirements with regard to other properties of thewall such as resistance to fire, thermal insulation, sound insulation or resistanceto rain penetration.

Stability Requirements
4.4.1

Lateral Support
Lateral support for a masonry element such as a wall or column is required:

4.4.2

a)

to resist horizontal components of the forces so as to ensure stability ofthe structure against over-turning; andb)to limit the slenderness of masonry elements in order to prevent failure
by buckling.

Adequate Lateral Support
A wall or column may be considered to be provided with adequate lateralsupport if the construction providing the support is capable of resisting thegreater of the following lateral forces :a)

The simple static reactions at the point of lateral support to the total
applied horizontal forces ; or 2.5 percent of the total vertical load thatthe wall or column is designed to carry at the point of lateral support.

Lateral support may be provided in either the vertical or horizontal direction.
Horizontal lateral support could consist of the floor/roof acting as a horizontal
girder capable of transmitting without excessive stresses the horizontal forces tocross-walls acting as stiffening walls. Vertical support could consist of
cross-walls/piers/buttresses capable of transmitting without excessive stresses
the horizontal forces to the foundation.

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9

4.5

Parapets and Compound Walls
4.5.1

GeneralSince, in the case of a free-standing wall such as a compound wall or parapet
wall, there is no lateral support at its top and no cross-walls to brace the same,stability shall be achieved by designing the wall as a gravity structure such thatthe factor of safety against overturning is at least 1.5. As straight walls
designed on this basis tend to be heavy, the stability of free-standing walls
greater than 0.9 m in height should be achieved by staggering or by theprovision of piers or buttresses. Even though a straight free-standing wall may
be stable with the stipulated factor of safety (1.5), it will have some tension,
because a condition of zero tension corresponds to a factor of safety of 3 against
overturning. Mortar used in masonry of a straight, free-standing wall should
not normally be weaker than type M1 indicated in Table 4.1 unless walls are
thick enough in relation to their height so as to be free from any tension.

4.5.2

Free-Standing Walls
A free-standing wall must be designed to be safe as a vertical cantilever. All
partition walls inside a building must be held on their sides as well as at their
tops.

4.5.3

Load Bearing Masonry Elements
In the case of an unreinforced load-bearing wall using ordinary Portland
cement, the slenderness ratio shall not exceed 17.

4.5.4

Slenderness Ratio
The slenderness ratio for a load-bearing column shall not exceed 12.

4.5.5

Curtain Walls
Curtain walls shall be designed as panel walls to resist lateral forces caused bywind or earthquakes in addition to their own weight. The junction details at thelateral supports shall be such that any vertical deformations or rotations of thestructural members providing the lateral support are not transferred to thecurtain wall. Similarly, there shall be freedom for the curtain wall to have
deformation in the vertical direction.

4.6

Structural Design
The specificaton laid down in clauses 5.1 to 5.5.5 of Indian Standard IS:1905-1987
shall apply to the structural design of masonry. The additional clauses as given here
under shall also apply.

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4.7

Design Method
The structural design of non-reinforced masonry shall be as per the design procedures
given below :4.7.1

Design Procedures
The building as a whole shall be analysed by accepted principle of mechanics toensure the safe and proper functioning in service of its component parts relative
to the whole building. All component parts of the structure shall be capable ofsustaining the most adverse combinations of loads to which the building may bereasonably expected to be subjected during or after erection.

4.7.2

Design Loads
Loads to be taken into consideration for designing masonry components of astructure are :

4.7.3

a)

dead load of walls, column, floors and roofs;b)live load on floors and roof;c)wind load on walls and roof; andd)seismic forces.

Design of Wall Footings
4.7.3.1 Depth of Footing
The net safe bearing capacity of the soil and the depth of foundation in
the soil are best determined by modern soil investigation methods. In
the absence of such an investigation report, a conservative minimum
depth of footing may be determined using the following formula :P
1 − Sinλ
1 + Sinλ

D=

2

W
where :
D = minimum depth of footing in metres.
P = net safe bearing capacity of soil (kPa).
W = unit weight of soil (kN/m3).
λ = angle of repose of soil in degrees.
Note :

NBC109V1.RV7

The above formula is not valid if the soil condition is Soft or
Weak as categorised in Table 7.1. In all

19 May 1994

11

cases, the footing should be founded below seasonal moisturevariation and to consistent bearing

4.7.3.2 Width of Footing
The minimum width of the footing, B, shall be obtained by dividing thetotal load (including dead loads), live and wind load) by the allowablebearing capacity of the soil :TB=P
where :

B = width of footing in metres.
T = total load per metre.
P = safe bearing capacity.
Note :

4.7.4

The above formula is not valid if the soil condition is Soft or
Weak as categorised in Table 7.1.

Permissible Compressive Stresses
The permissible compressive stresses shall be in accordance with the IndianStandard IS : 1905-1987 in which the design value of permissible compressive
stress, fc , depends on a combination of the following factors :1)

basic compressive stress based on type and strength of the masonryunits and mix of mortar, fb

2)factor for slenderness ratio and eccentricity of masonry elements, kse

3)factor for shape and size of the masonry unit, kp

4)

factor for cross-sectional area of masonry, ka and5)factor for load type, kl

so that :fc= fb kse kp ka kl
The values of the basic compressive stresses and the various factors are given in
IS : 1905-1987, clause 5 and its subclauses.

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5

General Requirements
5.1

Deforming and Cracking
Special provisions shall be made to control or isolate thermal and other movements sothat damage to the fabric of the building is avoided and its structural sufficiency ispreserved. The design and installation of joints shall be done in accordance withaccepted practice.

5.2

Cutting and Chasing
As far as possible, service (Electrical, Plumbing, etc.) should be planned with the helpof vertical chases. Horizontal chases should be avoided.
For load-bearing walls, the depth of vertical chases and horizontal chases shall not
exceed one-third and one-sixth of the thickness of the masonry, respectively.
No chase shall be permitted in a half-brick load-bearing wall.

5.2.1

Stretches of Masonry
When narrow stretches of masonry (or short lengths of wall), such as between
doors and windows, cannot be avoided, they should not be pierced with
openings for soil pipes or waste pipes or timber joists, etc. Where there is apossibility of load concentration, such narrow lengths of walls shall be checked
for stresses and high-strength bricks/mortar or concrete walls provided, if
required.

5.2.2

Horizontal Chases
Horizontal chases, when unavoidable, shall be located in the upper or lower
thirds of a storey and not more than three chases should be permitted in any
stretch of a wall. No continuous horizontal chase shall exceed one metre in
length.

5.2.3

Vertical Chases
Vertical chases shall not be closer than two metres in any stretch of a wall.
These shall be kept away from the bearing of beams and lintels. If unavoidable,
stresses in the affected area should be checked and kept within permissible
limits.

5.2.4

Masonry Directly Above A Recess
Masonry directly above a recess, if wider than 30 cm (horizontal dimension),should be supported on lintel. Holes in masonry up to 30 cm width x 30 cm
high may be provided without a lintel. In the case of circular holes in masonry,a lintel should be provided only if arch action can not be achieved.

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5.3

WorkmanshipThe quality of workmanship has considerable effect on the strength of masonry and badworkmanship may reduce the strength of brick masonry to as low as half the intended
strength. The basic compressive stress values for masonry given in IS : 1905-1987,
Table 8 are appropriate for commercially-obtainable standards of workmanship with areasonable degree of supervision. If the work is going to be inadequately supervised,
design strengths should be reduced to three-quarters of these values.

5.3.1

Bedding of Masonry Units
Masonry units shall be laid on a full bed of mortar with the frog, if any, upward
and so that cross-joints and bed-joints are completely filled with mortar.
Masonry units which are moved after their initial placement shall be re-laid infresh mortar. Old or disturbed mortar shall be discarded.

5.3.2

Bond
The cross-joints in any course of one brick thick masonry walls shall be not lessthan one quarter of a masonry unit in horizontal measurement from thecross-joints in the course below. In masonry walls more than one brick inthickness, bonding through the thickness of the wall shall be provided by either
header units or by other equivalent means.

6Special Considerations for Earthquake Resistance
6.1

Siting
The site should be free from landslide and rock fall areas and liquefaction potential(loose, saturated sand up to about six metres depth below the ground surface). See
NBC 108-94 Site Considerations for more details.

6.2

General Concepts
6.2.1

Categories of Buildings
For categorizing buildings for the purpose of achieving seismic resistance ateconomical cost, three parameters turn out to be significant :a)

Seismic Intensity Zoning where the building is located,b)

Important of the building andc)

Stiffness of the foundation soil.

A combination of these parameters will determine the extent of appropriate
seismic strengthening of the building.

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6.2.2

Seismic Zoning
The variation in seismic hazard with location in Nepal is defined for design
purposes in Figure 8.2 of NBC105-94 Seismic Design of Buildings in Nepal.
For the purpose of the design of unreinforced masonry, a simplified zonation
based on this figure shall be used.
Three zones A, B and C are defined in Table 6.1 and are shown in Figure 6.1
below.
Zone

Zone CoefficientA

Z ≥ 1.0B

0.8 ≥ Z > 1.0

Moderate Damage

C

Z < 0.8

Minor Damage

Table 6.1 :
6.2.3

Risk
Widespread Collapse and Heavy Damage

Seismic Zones for Unreinforced Masonry

Importance of Building
The importance of the building should be a factor in grading it for strengthening
purposes. Importance depends upon its occupancy, use and need before andafter a disaster as given in Table 6.2.

0.8

Zone A

Zone C

0.8

Zone B

0.9

1.0

1.0
0.8

Kathmandu

Zone B
Zone C

0.9

Zone A

Figure 1.1: Seismic Zoning Map of Nepal for this MRT

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15

Occupancy Category

Occupancy Type or Function of Structure

IMPORTANT CATEGORY
Hospital and other medical facilities

1. Essential Facilities

Fire and Police Station
Tanks or other structures containing, housing or
supporting water or other fire-suppression material or
equipment required for the protection of essential or
hazardous facilities.
Emergency vehicle shelter and garage
Structures and equipment in emergency-preparedness
centres and relief stores.
Power stations and standby power-generating
equipment for essential facilities
Structures and equipment in communication centres eg.
radio, television facility, telephone exchange etc.
Food storage structures
Offices and quarters for personnel related to central anddistrict level rescue and relief operations eg. ministers,
secretaries, police and army chiefs, CDO, LDO, DDC
chairman, district level army and police chiefs
2. Places of Assembly

Schools, colleges, hostels
cinema hall, culture, covered hall convention halls,
temples, dharmashalas

3. Monumental Buildings

Historic buildings, palaces

4. Distribution Facilities

Gas or petroleum products in urban areas

5. Hazardous Facilities

Structures housing, supporting or containing sufficientquantities of toxic or explosive substances to be
dangerous to the safety of the general public if release

ORDINARY CATEGORY
6. Ordinary Occupancy
Structures

Table 6.2 :NBC109V1.RV7

Any structure / building not described above eg
residential, offices, etc.

Occupancy Category

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16

The buildings under the Important category have been subdivided into two groups from a
constructions point of view. These are :7

A.

Buildings in accessible areas where modern materials such as cement and reinforcing
bars can be easily transported

B.

Buildings in remote inaccessible areas to where modern materials can not easily betransported.

Site Considerations
7.1

GeneralThis section sets out some of the requirements to be considered during site selection forthe construction of buildings in order to minimise the risks to buildings from bothprimary geological hazards and secondary seismic hazards such as fault rupture,landslide and liquefaction. Since this is the first such effort to introduce the importanceof geotechnical conditions and the nature of foundation soil in the stability of Nepalesebuilding, the requirements set out here have deliberately been kept low to encourage
effective implementation.

7.2

General Considerations
As a good practice during the construction of a building, it is necessary to examine all
existing local knowledge and the performance histories of existing building. The
designer should thus be able to identify any dangers from an inherent naturalsusceptibility of the land to the processes of sliding, erosion, land subsidence andliquefaction during past earthquakes, or from any other natural/geological process
likely to threaten the integrity of the building. The local practice of managing suchhazards, if any, should be judged against the required level of acceptable risk.

7.3

Site Investigation Requirements
For load-bearing masonry buildings and reinforced concrete (RC) frame buildings withmasonry infills, site exploration should be carried out by digging test pits, two as aminimum, and more if the subsurface soil conditions show a variation in soil types.
Generally the depth of exploration for the buildings should be a minimum of two
metres. In hilly areas, exploration up to the depth of sound bed rock, if it lies shallower
than two metres, should suffice.
No exploration shall be required if the site is located on rock or on fluvial terraces (Tar)with boulder beds.

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The soils encountered in the test pits should be classified as per Table 7.1.

7.4

Allowable Bearing Pressure
The allowable bearing pressure could be calculated using the Table 7.1. in conjunction
with the visual classification of the subsurface soil type.

Foundation
Classification

Presumed Safe
Bearing
Capacity(kN/m2)Rocks in different state of weathering;boulder beds; gravel; sandy gravel and sandgravel mixtures; dense or loose coarse to
medium sand; offering high resistance topenetration when excavated by tools; stiff tomedium clay which is readily indented with athumb nail.

Hard

≥ 200

Fine sand and silt (dry lumps easily
pulverised by the finger); moist clay andsand-clay mixtures which can be indented
with strong thumb pressure.

Medium≥ 150 and < 200

Fine sand; loose and dry; soft clay indented
with moderate thumb pressure.

Soft≥ 100 and < 150

Very soft clay which can be penetrated
several centimetres with the thumb; wet clays.

Weak

≥50

Type of Soil/Rock

Table 7.1 :Classification of Foundaton Soil And Safe Bearing Capacity

Buildings can be constructed on hard, medium and soft soils but it will be dangerous tobuild them on weak soils. Hence, appropriate soil investigation should be carried out toestablish the allowable bearing capacity and nature of soils. Weak soils must be
avoided or compacted to improve them so that they qualify as at least Medium or Softsoils.

7.5

Combination of Parameters
For determining the categories of building for seismic strengthening purposes four
categories (I to IV) are defined in Table 7.2 in which category I will require maximum
strengthening and category IV the least. The general planning and designing principles
are, however, equally applicable to all categories.

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Category

Combination of Conditions for the Category

I

Important Building on Soft Soil in Zone A

II

Important Building on Firm Soil in Zone A
Important Building on Soft Soil in Zone B
Ordinary Building on Firm Soil in Zone A

III

Important Building on Firm Soil in Zone B
Important Building on Soft Soil in Zone C
Ordinary Building on Firm Soil in Zone A
Ordinary Building on Soft Soil in Zone B

IV

Important Building on Firm Soil in Zone C
Ordinary Building on Firm Soil in Zone B
Ordinary Building on Firm Soil in Zone C
Ordinary Building on Soft Soil in Zone C

Table 7.2 : Categories of Buildings for Strengthening Purposes

Notes :

NBC109V1.RV7

i)Seismic Zones A, B and C are as per Figure 6.1

ii)

Weak soils liable to compaction and liquefaction under earthquake conditions
are not covered here.

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19

Crosswal

L1

L2

h1

b5

b7

b6

h2

b3

h2

b2

b1

h3

b9

b4

b4

b4

b4

Note:
i)

b1+b2+b3<0.5 L1 for one storey,<0.42 L1 for two-storeyed,<0.33 L1 for three-storeyed

ii)

b6+b7

<0.5 L1 for one storey,<0.42 L1 for two-storeyed,<0.33 L1 for three-storeyed

iii)

b4

>0.5 h, but not less than 600 mm

iv)

b5

>0.25 h, but not less than 600 mmv)

b3> 600 mm and > 0.5 (bigger of b2 and b9)

Figure 7.1 : Recommendations Regarding Opeinings in Bearing Walls

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ALTERNATIVE - 1

ALTERNATIVE - 2

V = 2, ØV = 1, Ø

SECTIONAL PLAN AT Y - Y

40d

40d

40d

40d

t1

Lintel band

W

W

t1

t1

or

V

V

SECTION AT X - X

1/2 L

3/4 L

L

25

1/2 L

V

V

2nd COURSE

1st COURSE∅ -- Diameter,

W -- Window,

V --- Vertical Reinforcing bar,t -- Thickness of wall ( minimu l brick length) ,t1 -- Minimum thickness 75 mm.,

L -- Length of brick unit.

Figure 7.2 : Strengthening of Masonry Around Openings

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8

Openings in Wallsa)Openings shall be located away from the inside corner by a clear distance equal to atleast one-quarter of the height of openings, but not less than 600 mm.

b)

The total length of openings shall not exceed 50 % of the length of the wall between
consecutive cross-walls in single-storey construction, 42 % in two-storey construction
and 33 % in three-storey buildings.

c)

The horizontal distance (pier width) between two openings shall not be less than onehalf of the height of the shorter opening (Figure 7.1), but not less than 600 mm.

d)

The vertical distance from an opening to an opening directly above it shall not be lessthan 600 mm, nor less than one-half of the width of the smaller opening (Figure 7.1)e)When openings do not comply with requirements (a) to (b), they should be boxed inreinforced jambs through the masonry (Figure 7.2)

f)Tops of openings in a storey should preferably be at the same level, so that acontinuous band which includes the lintels throughout the building can be provided.

g)

If a window or ventilator is to be projected out, the projection shall be in reinforced
masonry or concrete and well-anchored.

h)

If an opening is tall enough with respect to the full height of wall so as to divide
effectively the wall into two portions, these portions shall be reinforced with at least 6
mm diameter horizontal bars at not more than 600 mm intervals on both the inner andouter faces. This steel at jambs and at corners or junctions of walls.

i)

The use of arches to span over the openings is a source of weakness and shall be
avoided unless steel ties are provided.

j)

All the walls must be effectively tied together to avoid separation at vertical joints due
to ground-shaking during an earthquake.

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9

Masonry Bond
9.1

Vertical Joints between Perpendicular Walls
A sloped or stepped joint should be made in order to obtain full bond by making thecorners first to a height of 600 mm and then building the wall in between them.
Alternatively, a toothed joint should be made in each wall alternately in lifts of about
450 mm, as shown in Figure 9.1.

230

c

B

450

230

450

450

230

c

A

450

b
c

a
c
b

a

All dimensions are in mm.
a, b, c Toothed joint in walls A, B and C( Alternating toothed joint in walls at corner and T-junctions )Figure 9.1: A Typical Detail of Jointing in Masonry

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10

Horizontal Reinforcement in Walls
Horizontal reinforcing of walls is required to give to them horizontal bending strength against
plate-action for out-of-plane inertia loads, and for tying orthogonal walls together.

10.1

Horizontal Bands or Ring Beamsa)

Plinth BandA plinth band should be provided in all cases where the soil is soft or uneven inits properties.

b)

Lintel BandThe lintel band shall incorporate all door and window lintels, the reinforcementof which should be extra to the lintel band steel. It must be provided in all
storeys in all walls of the buildings as per Table 11.1.

c)Roof BandA roof band shall be provided at the eave-level of trussed roofs (Figure 4), andalso below or in the level of such floors that consist of joists and covering
elements so as to properly integrate them at their ends and fix them into thewalls.

d)

Gable Band
Masonry gable-ends must have the triangular portion of masonry enclosed in aband, the horizontal part of which will be continuous with the eave-level bandon longitudinal walls (Figure 10.1).

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G
G

R

R

1

L

2
1

( a)

2500

R

L - Lintel band,( b )DETAIL AT - 1
Note:

R - Roof band
G - Gable band( c ) DETAIL AT - 2( Fixing of roof to wall )i) As an alternative to the gable masonry, a truss or open gable may be used and the openings
covered with a light material such as sheeting, matting etc.
ii) If the wall-height up to eave-level is less than or equal to 2.5 m , the lintel-level band may beommitted and the lintel integrated with the eave-level band as shown in Detail 2.

Figure 10.1 : Gable Band and Roof Band in Barrack-Type Buildings

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11

Section of Bands or Ring Beams
A band consists of two (or four) longitudinal steel bars with stirrups embedded in 75 mm (or150m mm) thick concrete (Figure 11.1 and 11.2).
The thickness of the band may be made equal to, or a multiple of, a masonry unit, and its width
shall equal the thickness of the wall.
The steel bars shall be located close to the wall faces with 25 mm cover, and full continuity
shall be provided at corners and junctions.

10Øs or 75mm whichever is greater
30

10Øs or 75mm whichever is greater
30

75

150

30

b
b

a) CROSS SECTION OF R.C. BAND FOR TWO BARS AND FOUR BARS OF DIA. '
b1

Ø'

b1

b2

> 150

> 150

b2

b) R. C. BAND REINFORCEMENT DETAILS AT CORNER AND T-JUCTIONb, b1, b2 = Wall thickness
2 strength.
Concrete
1 : 2 : 4 or 15 N/ mm cube

Note:
Provide overlaps for slicing bars outside the corner length of overlap
to develop full band say 50 d.

Figure 11.1 : Reinforced Concrete Band and Details

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26

60
30

60

60

30

75

150

30

b

6Ø@150or5b

6Ø@150or5a) CROSSSECTIONOFR.C.C. BANDFORTWOBARSANDFOURBARS
b1

b1

b2

b2

b) R. C. BANDREINFORCEMENTDETAILSATCORNERANDT-JUCTIONb, b1, b2 = Wall thickness
2 strength.
Concrete 1 : 2 : 4or 15 N/ mm cube

Note:
Provideoverlaps for slicing bars outside the corner lengthof overlap
todevelop full band say50d.

Figure 11.2: Reinforcement inReinforcedConcreteBand

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Longitudinal steel in Reinforced Concrete (RC) Bands
Span ofwall
between
cross
wall
(m)

Category I
No.
of
Bars

Category II

Bar Dia.
(mm)

T*

K*

No.
of
Bars

Category III

Bar Dia.
(mm)

T

K

No.
of
Bars

Category IV

Bar Dia.
(mm)

T

K

No.
of
Bars

Bar Dia.
(mm)

T

K

5 or
Less

2

10

9

2

10

9

2

10

9

2

10

9

6

2

12

-

2

10

9

2

10

9

2

10

9

7

2

12

-

2

12

-

2

10

9

2

10

9

* T = High strength bar having an fy of 415 N/mm² (Fe 415 Grade)
K = High strength bar having an fy of 550 N/mm² (Fe 550 Grade)

Table 11.1 : Recommendation for Steel in RC Bands

Notes :
i)

Width of the RC band is assumed to be the same as the thickness of wall. Wall thickness
shall be 230 mm minimum. A cover of 25 mm from face of wall shall be maintained.

ii)

The vertical thickness of a RC band may be kept to a minimum of 75 mm where twolongitudinal bars are specified and 150 mm where four longitudinal bars are specified.

iii)

Concrete mix to be 1:2:4 by volume or to have an M15 Grade cube crushing strength
at 28 days.

iv)

The longitudinal bars shall be held in position by steel stirrups 6 mm in diameter
spaced no more than 150 mm apart.

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12

Dowels at Corners and Junctions
Steel dowel bars shall be used at corners and T-junctions to integrate the box action of walls.
Dowels (Figures 12.1, 12.2, 12.3 and 12.4) are to be taken into the walls to a sufficient length
so as to provide their full bond strength.

t11.20 - 1.50 m

Ø5 - 8 mm
1.20 - 1.50 m

Ø5 - 8 mm

Ø5 - 8 mm

1.20 - 1.50 m

l1.20 - 1.50 m

Ø5 - 8 mm

t2

Ø5 - 8 mm

1

Ø5 - 8 mm

500 - 700 mm

2

500 - 700 mm

2

2

t 1, t 2 = Wall thickness
1= Cross links
2= Thick joints to receive dowels

Figure 12.1 : Corner-Strengthening by Dowel Reinforcement Placed in One Joint

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t1

1.20 - 1.50m

Ø5 - 8mm
1.20 - 1.50 m

Ø5 - 8mm

1.20 - 1.50m

1.20 - 1.50 m

1

Ø5 - 8mm

Ø5 - 8mmt2

1

Ø5 - 8mm

Ø5 - 8mm

500 - 700 mm
500 - 700 mm

2
2

2
2

500 - 700 mm

2
2

t 1, t 2 = Wall thickness
1= Cross links
2= Thick joints to receive dowels

Figure 12.1 : Corner-Strengthening by Dowel Reinforcement Placed in Two Consecutive
Joint

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t2

1.20 - 1.50 m

l

l

t1

Rods Ø 5 - 8 mm

Ø 5 - 8 mm

1.20 - 1.50 m

1.20 - 1.50 m

t 1, t 2 = Wall thickness,l = Cross links

Figure 12.3 : T-Junction Strengthening by Dowel Reinforcement1

1.20 - 1.50 m

1.20 - 1.50 m

1

2

2

Figure 12.4 : Strengthening by Wire Fabric at Junctions and Corners

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13

Vertical Reinforcement in Walls
Steel bars shall be installed at the critical sections (i.e. the corners of walls and jambs of doors
right from the foundation concrete) and covered with cement concrete in cavities made aroundthem during masonry construction (Figure 13.1). This concrete mix should be 1:2:4 byvolume or stronger.
The vertical steel at an opening may be stopped by bending it into the lintel band but thevertical steel at corners and junctions of walls must be taken into the floor slab, roof slab, orroof band.

NumberofStoreysStoreyOne

Diameter of mild steel single bar in mm at eachcritical section by Category
Category I

Category II

Category III

12

10

10

Two

Top
Bottom

12
16

10
12

10
12

Three

Top
MiddleBottom

12
16
16

10
12
12

10
10
12

Table 13.1 :Recommendation for Vertical Steel at Critical Sectionsi)

The above vertical reinforcement in walls is valid for up to threestoreyed buildingsii)

Four-storeyed and above load-bearing wall construction may not be
used for categories I and II buildings.

Notes :

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32

1

1/2 1/2 1/4 1/2 1/2 1/2

1

1 /2

1 /2 1 /4 1 /2

V

1

1

1/2 1/2

1

V

1 /2

1 /2 1 /2

F I R S T LAYER

1 /2

1

S E C O N D LAYERC OR N E R JU N C TION D ET A ILS F OR O N E B R IC K W A L L FOR
P R O VID IN G V ER TIC A L ST EE L.
1 1 /2
1/2 1/2 1/2 1/2 1/2
1 1/2
1 /2

1 /2

1 /2 1 /2 1 /2V

1/2 1/2 1/2

V

1 /2 1 /2 1 /2

1 1/2

1/2 1/2 1/4 1/2 1/2 1/2 1/2 1/2

1 1 /2

1 /2 1 /2 1 /4 1 /2 1 /2 1 /2 1 /2 1 /2

F I R S T LAYERS E C O N D LAYERC OR N E R JU N C TION D ET A ILS F OR O N E A N D H A L F B R IC K
W A L L F O R P R O V ID IN G VER TIC A L STEEL.
1 1 /2

1 /2 1 /2 1 /4 1 /2

1 /2 1 /2 1 /2 1 /2

1 /2 1 /2 1 /4 1 /2 1 /2

F I R S T LAYER

1 /2

1 1/2

V

1 1/2

V

1/2 1/2 1/2 1/41/2 1/2 1/2

1/2 1/2 1/2 1/2 1/2 1/2 1/2

1 1 /2

1 /2 1 /2 1 /2 1 /2

S E C O N D LAYER

T - JU N C TION D ET A ILS F OR O N E A N D H A L F B R IC K W A LL
F OR P R O VID IN G V ER TIC A L ST EE L.
1

14, 2 , and 1 indic ates:
V - Vertic al Bar

1

4

Brick wid e,

1

2 Brick wid e, 1 B ric k long etc.,

F ig u re 13.1 : V e rtic a l R e in fo rcem ent in W alls

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14

Reinforcement Details for Hollow Block Masonry
14.1

Horizontal BandU-shaped blocks should be used for the construction of horizontal bands at various
levels of the storey as per seismic requirements as shown in Figure 4.1.
The amount of horizontal reinforcement shall be taken as 25 % more than that given in
Table 11.1 and provided by using four bars and 6 mm diameter stirrups.

1

2

3

1 - Lintel Band
2 - Roof Band ( only for pitched roofs and under roofs and floor )3 - Vertical steel.

Figure 14.1 : Overall Arrangement of Reinforcing Masonry Buildings

NBC109V1.RV7

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15

Vertical Reinforcement
The vertical bars specified in Table 13.1 can be conveniently located inside the cavities of thehollow blocks - one bar in one cavity. Where more than one bar is planned, these can belocated in two or three consecutive cavities as shown in Figures 15.1 and 15.2.

15.1

NBC109V1.RV7

Infill Panels and Non-Structural Wallsa)

In-fill panel walls in a building shall be designed to ensure that they act together
with the frame in full composite action.

b)

The seismic load at each level shall be distributed to the individual wall in
proportion to the product of each wall's thickness and length. This product isrepresentative of the diagonal strut area and thus of the wall's shear stiffness.

c)

Any frame is to be designed to resist all the gravity loads without any assistancefrom the infill walls as these walls may either fail or be very severely damaged
in a large earthquake.

d)

The centre of rigidity of the infill walls (except face wall) shall be as near as
possible to the centre of rigidity of the complete system of walls.

e)

An infill wall shall be so designed that it sustains minimum damage during any
deflection of the supporting structure during an earthquake and shall be
designed to resist all action resulting from in-plane and face loads.

f)

The minimum thickness of an infilled wall shall be the same as that of partition
walls, and its openings should be as small as possible and cover not more than
10 % of the panel area. The preferable location of an opening in a wall is
outside the central two-thirds of the sides and away from the corners. If the
opening must be near the centre of the wall, it shall be bounded by a reinforced
concrete beam 75 mm thick, the other dimension to be equal to thickness ofwall and reinforced with two 10 mm diameter Fe 415 grade bars longitudinallyand 5 mm diameter Fe 550 grade bar link ties .

g)Partition walls shall have a minimum thickness shall have horizontal
reinforcement (one 6 mm diameter bar in each face) in every sixth course ofblockwork.

h)

If the infill wall is constructed in a Category I or II building, the thickness ofinfill wall shall not be less than 230 mm.

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35

30 Ø

30 Ø

Figure 15.1 : Vertical Reinforcement inBlockwork Cavities

Ø

( a)
( b)

Figure 15.2 : Vertical Reinforcement inCavities

NBC109V1.RV7

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16

Wall Thickness and Spacing

The minimun thicknesses and maximum spacings of masonry walls shall be as dexcribed inTables 16.1 and 16.2.

*

Height of Wall (m)Length of Wall (m)Thickness of Wall at
Base (Bricks)

1.

Up to 4.5

Any*

1.5

2.

4.5 to 7.5

Any*

1.5

3.

7.5 to 9

Up to 14
Above 14

1.5
2

4.

9 to 12Up to 99 to 14
14 to 18

1.5
2
2.5

5.

12 to 15

Up to 99 to 182
2.5

6.

15 to 18

Up to 99 to 14

2.5
3Provision should be made for expansion/contraction joints.

Table 16.1 :Buildings

Thickness of Walls for Public Buildings, Warehouse and Incustrial

Notes :

NBC109V1.RV7(i)

An additional thickness of one-half a brick at the base will usually be
sufficient where vibrating machinery is used.

(ii)

The base thickness is reduced towards the top; for 5 m from the top ofwall, the thickness should be 1.5 bricks, but where the wall does notexceed 9 m in height, the wall for 3.5 m from the top may be one brickthick if the wall is in a cement mortar.

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37

Thicknessof LoadBearing
Wall to be
Stiffened(mm)

Height* ofStorey not
to exceed(m)

Stiffening Wall*
Thickness not less than(mm)

1 to 3storeysMax.
Spacing(m)

4 to 6
storeys

1.
100
3.2
240
4.5
2.
240
3.2
360
480
6.0
*
Storey height and maximum spacing are given as centre-to-centre dimensions.

Table 16.2 :NBC109V1.RV7

Thickness and Spacing of Stiffening Walls

19 May 1994