I plan to do wainscotting on the lower half of the walls in my bathroom reno, which has been demoed down to the studs. In order to gain a bit of space, I’m wondering if it’s OK to only sheetrock the top half of the walls then apply the wainscoting below, which will be made from 1×3’s and 1/4″ MDF or plywood panels, directly to the studs. It’s a multi-unit building, one wall is exterior, but none of the walls are separating another unit. I have a feeling I need the 5/8″ fire rated rock (which will be used everywhere else) covering all the joist spaces, but could I “inset” the rock to be flush with and sealed to the studs to meet that requirement?
Thanks
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Your local code may be different from where I have worked, but typically in wood framed residential multi unit structure they only require the fire rating between units, shared stairways and walk ways. Also, if a neighboring property is close to the exterior wall, the exterior wall may need the fire rating as well. All walls within the fire rated envelope do not need to meet the fire rating, but codes still apply to the walls. Any penetrations in the floor or ceiling need to be fire stopped according to IBC requirements (not IRC), so can’t use a can of great stuff foam to seal the penetrations. Again, this is all based upon my local enforcement. Always best to check with the specifics of yours.
Thanks- the exterior wall of the adjacent building is 3’ away so I assume the fire rating would be applicable.
Do you think sealing the cavities as I suggested (flush with the stud faces) would be acceptable?
Thanks
I don’t believe it would be acceptable. I’ve never encountered or seen an approved fire rated assembly as to what you are describing. Inspectors and building departments will only approve UL listed assemblies, so there’s no creative solution for you to come up with. You have to abide by UL listed assemblies and not deviate from what has been designed and tested. Also, your building officials will require you to call out the UL listing being used in order to pass, so they can check to make sure your specific UL listing is installed correctly. There are quite a few resources online for free at the major drywall producers websites (USG is a good one). You may find a listing that will work for you, but I don’t think you will. I may be wrong, I don’t have all the listings memorized. Probably going to need to leave the drywall in place and apply wainscoting over it.
Makes sense, guess I'll just have to sacrifice that 5/8". I'll live.
Thanks