Publisher’s version / Version de l'éditeur:
Technical Note (National Research Council of Canada. Division of Building Research), 1967-10-01
READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.
https://nrc-publications.canada.ca/eng/copyright
Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à [email protected].
Questions? Contact the NRC Publications Archive team at
[email protected]. If you wish to email the authors directly, please see the first page of the publication for their contact information.
NRC Publications Archive
Archives des publications du CNRC
For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien DOI ci-dessous.
https://doi.org/10.4224/20358667
Access and use of this website and the material on it are subject to the Terms and Conditions set forth at
Fire Protection in Wood-Frame Construction
Galbreath, M.
https://publications-cnrc.canada.ca/fra/droits
L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.
NRC Publications Record / Notice d'Archives des publications de CNRC:
https://nrc-publications.canada.ca/eng/view/object/?id=aa2a7b6d-571d-4e2c-8474-a0ff2f3bd838 https://publications-cnrc.canada.ca/fra/voir/objet/?id=aa2a7b6d-571d-4e2c-8474-a0ff2f3bd838
DIVISION OF BUILDING RESEARCH
NATIONAL RESEARCH COUNCIL OF CANADA
'JrE
C
1HlN ][ CAlL
NOTJE
No.
505
LIMITED
DISTRIBUTIO,\J
PREPARED BY M. Galbreath CHECKED BY G. W. S. APPROVED BY R. F. L. DATE October
1967
ＮＮＺＮＮＮｐＮＺＮＮＺＮｒ］ｅＮＮＮＮＮＬｐａ］ｒＮＮＢＢｅ］ＮＺｄｾｆｾｏｾｒｾ Visiting Housing Missions to DBR/NRC
SUBJECT FlRE PROTECTION IN WOOD-FRAME CONSTRUCTION
When wood is exposed to fire the exposed surfaces are gradually destroyed, the depth of char advancing at a rate of about 1/40 in. (5/8 mm) per minute. This applies to most of the woods used in norm.al construction. Massive timber rn.ern.bers can therefore retain their strength for extended periods although they are gradually' reduced by the fire.
Wood-frame construction consists of large numbers of small members (e.g. 2 in. by 4 in., (5 cm by 10 cm), etc.}. These lose their strength rapidly as the surfaces' are charred. In this type of construction emphasis is placed on the protection afforded by the membrane or surface skin on the side exposed to fire.
The protective wall or ceiling finish may be plaster on metal lath, plaster on gypsum lath, wallboard, plywood, or other finish. The most important characteristic of the membrane is its ability to stay in place. This is of particular significance in ceilings. Plaster on metal lath behaves well in fire; the per-formance of other plaster ceilings is improved when reinforced by wire mesh. A gypsum wallboard in common use in Canada contains a fibreglass reinforcement for the same reason. The method of fastening is also of importance and has to be considered
4 f , _
2
-in any design. Deeper penetration of nails or screws generally gives better fire performance. Fire endurance of up to 2 hr
can be provided in wood-frame construction. This fire endurance is based on the ASTM fire test which has a time temperature pattern very similar to that of the fire test used in France.
The interior finish forms the fir st line of defence against fire. This is, however, very often penetrated by open-ings for electrical outlets, lighting fixtures, and air diffusers. These should be tight fitting to provide some protection against fire. If fire does get into the hollow spaces in frame cons truction, . it may spread very quickly and in an upward direction because of
"chimney" action. In order to reduce this probability it is good practice to provide fire stops between studs at each floor level and between joists where these pass over walls. These may be of 2-in. (5-cm) wood or of a noncombustible material tightly fitted into the spaces.
Fire retardant impregnation of the wooden frame members will reduce the probability of spread of flame in the construction spaces. It does not, however, add significantly to the fire endurance of the assembly as a whole.
Wood-frame construction is permitted by the National Building Code of Canada for .apartment buildings of up to 3 storeys in height. For buildings of this height, sufficient protection can be provided to permit evacuation of occupants an'! access for fire fighters. In higher buildings where structural stability must be ensured during and after a fire of any magnitude, fire protected noncombustible construction is required. Nevertheless the
National Building Code of Canada permits wood-frame non-loadbearing partitions within each dwelling unit provided the dwelling units are separated from each other with fire resistive noncombustible con-struction.
The Residential Standards (supplement No. 5 to the N. B. C. ), which are used as minimum requirements for houses built under the National Housing Act, contain a listing of fire-resistance ratings for various floor and wall constructions both for combustible and noncombustible construction. In addition, Supplement No.2 to the National Building Code provides comprehensive design data to enable .the calculation of fire resistance for a wide variety of constructions.
