Hello, all.

I realize that different jurisdictions will have slightly different fire/building codes, so am looking for a general response.

One of the main reasons I am interested in SIP's (beyond all of the other obvious ones) is to reduce the cost of interior wall finishing.  If I can use the OSB interior sheathing as a finsihed material then I can save on hanging, taping and mudding gyproc (sheetrock).

My question is: Are there basic ideas/stats about the fire-rating of an OSB SIP? Does the OSB provide sufficient time before the heat/fire gets into the foam core?

As an added question: If the fire gets into the foam core, what are the results (seriously deadly fumes? rapid fire development?)?

Thanks
North-Cooke

they have no fire rating ...most SIPs (EPS) use a self extinguising foam that will only burn if there is another fire source, fumes are less noxious than furniture/carpet

if it has  burned to the inside of the wall/roof  you have been dead a long time

North-Cooke,

Here is an excerpt from the International Building Code.

R314.1.2 Thermal barrier. Foam plastic, except where
otherwise noted, shall be separated from the interior of a
building by minimum1/2-inch (12.7 mm) gypsum board or
an approved finish material equivalent to a thermal barrier to
limit the average temperature rise of the unexposed surface
to no more than 250 degrees F (121 degrees C) after 15 minutes of fire expo-
sure to the ASTM E 119 standard time temperature curve.
The gypsum board shall be installed using a mechanical fas-
tening system in accordance with Section R702.3.5. Re-
liance on adhesives to ensure that the gypsum board will re-
main in place when exposed to fire shall be prohibited.

This means gypsum wall board is required.

North-Cooke,

Another aspect of SIP construction that makes it makes more fire proof, is the absence of wall cavities and open attics spaces. These spaces allow a fire to breath thus giving the fire what it needs to spread.

you can also paint with intumescent paint http://www.contegointernational.com/

but it is cost prohibitive

Doesnt 3/4 tounge and groove wood typically meet this requirement?

Posted By Brawler on 15 May 2010 08:39 AM
Doesnt 3/4 tounge and groove wood typically meet this requirement?

yes