A garage below a bedroom has the required 5/8-inch Type X ceiling separation and the required wall separation. Steel beams and columns supporting that floor-ceiling assembly are exposed with no equivalent protective covering. Under 2021 IRC Table R302.6, what protection is required on those supporting members?
- At least 1/2-inch gypsum board or equivalent
- BNone, because steel is noncombustible
- CNone, because only ceiling and wall membranes are regulated
- DOnly 5/8-inch Type X gypsum board is permitted, with no equivalent option
Where to look it up
https://codes.iccsafe.org/content/IRC2021P1/chapter-3-building-planning
Why A is correct
Table R302.6 separately lists structures supporting the floor-ceiling assemblies used for the required separation. Their minimum protection is 1/2-inch gypsum board or equivalent. Noncombustible steel is not an exemption from this table row. The ceiling beneath habitable rooms has its own 5/8-inch Type X-or-equivalent row. R302.6 directs gypsum attachment to Table R702.3.5; this question does not establish a fastening violation from an unspecified screw pattern or predict an appeal outcome. Source: https://codes.iccsafe.org/content/IRC2021P1/chapter-3-building-planning