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

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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

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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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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

TRADITIONAL
MATERIALS &CONSTNN> 3
STOREYS
ETC ?

Y

N
Y

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

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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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