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.RV47 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.RV47 February 1994

iPrefaceThis 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 ofNepal'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 ProjectNEP/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 ProjectPresident, 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 CONTENTSPreface..................................................................................................................................................i0Foreword....................................................................................................................................iv

1.

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

NEPAL AMENDMENTS TO IS: 874 (Part 4) –1987..................................................................... 10Foreword................................................................................................................................. 11. ...................................................................................................................................................... 23............................................................................................................................................................ 24............................................................................................................................................................ 26............................................................................................................................................................ 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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11.

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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2In 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 issharply 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 , and0O < 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. Importedcorrugated 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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3TABLE 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

SlopeMean
Depth ofSnow(cm)

StandardDevi
ation of Snow

Number ofObserveationsDensity(gm/cm3)

Water
Equivalent(mm)5000 to4920

Varies

33.0

46.2

145

0.320

107.0

Density quite
variable3900

SW

16.6

1.3

140.069

11.5

Just able to snow
fall

3700

W

16.9

2.5

150.11

19.0

Just after snow fall

W

15.4

0.8

100.134

21.0

15.7

1.5

100.126

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

150.123

4227-II-91

Kyanging basehouse3900

SW

19.2

3.0

57

0.11

20

27-II-91

Kyanging basehouse3900

SW

16.7

3.3

120.11

18.5

Source : Snow and Glacier Hydrology ProjectRemarks

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4SIMIKOTDARCHULACHAINPURBAITADI

MARTADI

DIPAYALDADELDHURA40JUMLA

08040SILGADHI

180 KM.

120

SCALE

MANGALSEN
MAHENDRANAGAR
DAILEKH

JOMSOM

JAJARKOTDHANGADHI

CHAME

BIRENDRANAGAR
SALYANLIBAN

BAGLUNGKUSMA

TULSIPURNEPALGUNJTAMGHASPYUTHANPOKHARADHUNCHEDHADINGBESIBUTWALSIDDHARTHANAGAR

SAGARMATHA( MT. EVEREST)GORKHASANDHIKHARKA

BIDUR

KATHMANDU

CHAUTARABHAKTAPUR

BHARATPURLALITPUR

DHULIKHELPATASISALLETIHETAUDARAMECHHAPKHADBARI

OKHALDHUNGASINDHULIMADIDIKTELLEGEND
INTERNATIONAL BOUNDARYHEADQUARTERS
CAPITALREGIONAL
ZONE & TOWNPEAK & PASSHIGH HIMALAYA ( PERSNOW)BIRGUNJBHOJPUR

TAPLEJUNG
PHIDIMTEHRATHUM

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