I've got this old building in Canada, nearly a century old, and I need to boost the fire resistance rating of the ground floor to 45 minutes. The current structure features bare 2x8 studs set about 20 inches apart, though this varies between 18 and 22 inches, plus the ceiling height is pretty low. I'm considering putting in rockwool insulation (5.5 inches thick) between the studs, followed by 5/8" Type X gypsum boards. Is that a solid approach, or would it be better to double up on the gypsum, even if that lowers the ceiling even more? I'm also concerned about the wires and plumbing that hang down; won't the rockwool make accessing those more difficult?
Additionally, there are large wooden beams under 6 feet high that also might need gypsum covering. I'm a bit lost on what's feasible here and my budget isn't great either.
2 Answers
Using 5/8" fire-rated drywall is a good choice because it actually provides up to a 1-hour rating. Don't forget to use fire-rated caulk to seal any gaps and openings, which is crucial. It's worth checking with your local authority to ensure everything meets their requirements, though!
Totally agree with the suggestion about 5/8" Type X drywall. It's important to know why the rating is necessary. If it's a city requirement because of changes in your property classification, make sure all ducts or any penetrations are sealed, or it might complicate things. Access may be an issue, especially with ductwork hanging low, so keep that in mind!
The basement is pretty much empty, just a staircase going down, although there is lots of ductwork under the studs. The city wants the rating because part of the property is now classified as non-residential due to an office being rented out. We didn’t change anything structurally, but now we have to meet fire codes to revert it back to residential. I think I might go with the 5/8" Type X option, despite my worries about electrical boxes and plumbing. I'm not sure how much it would cost if I hired someone to handle it all, though.