Question
I would like to know if TallWall Wall Sheathing, Windstorm Wall Sheathing, and Solarbord Radiant Barrier Sheathing meet the requirements of classification B when tested in conformance with CAN4-S124-M; “Test for the Evaluation of Protective Coverings for Foamed Plastic”.
Bob Hilson, Kingston, ON
Answer
Thank you for the email and question Bob. I took your question to the APA as this was a question we had not been asked before.
APA response:
The requirements differ considerably depending upon application i.e. combustible or non-combustible construction.
If one looks to the National Building Code of Canada (NBCC) for guidance protection of foam plastic for ‘combustible construction’ has an either or compliance method. You can meet 3.1.4.2.a by using any interior wall finish in subsection 9.24.4 to 9.29.9. OSB falls under section 9.29.9 so it meets the requirement. The alternative would be meeting 3.1.4.2 c which of course is meeting S124.
Combustible construction, on the other hand, falls under Section 3.15.11 (2) the requirements are as follows:
- not less than 12.7 mm thick gypsum board mechanically fastened to a supporting assembly independent of the insulation
- lath and plaster, mechanically fastened to a supporting assembly independent of the insulation
- masonry
- concrete or
- any thermal barrier that meets the requirements of classification B when tested in conformance with CAN4-S124-M, Standard Method of Test for the Evaluation of Protective Coverings for Foamed Plastic (See Appendix A).
As far as I know OSB will not meet classification B under S124 without a Fire Retardant Paint.