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My house is a fairly typical US split-level from the mid-50s. It has a two-car garage with the master bedroom and bathroom above. The garage ceiling is simply open floor joists, with some fiberglass insulation stuffed in at random, which of course doesn't meet fire code. We've only been here about a year but it doesn't look like there was ever any more ceiling than what's there now.

The obvious solution is to put up drywall per code; however I've been spoiled by only ever living in single-level homes with crawlspace or unfinished basement access, and it pains me to seal in that convenient access to the wiring, plumbing, and HVAC that runs to the bedroom and bathroom. Ideally I'd like some kind of ceiling surface that can be taken down and replaced in a matter of hours if I want to get behind it, without replacing or patching sheetrock.

The relevant part of the IRC (which my city and state follow), R302.6, states that garage ceilings below habitable space must have "Separation" of "Not less than 5/8-inch Type X gypsum board or equivalent."

The question: is there an established "equivalent" to the 5/8" Type X gypsum board required by code for a garage ceiling, preferably one that is easier to remove and reinstall? IRC R302.11.1 includes a list of fireblocking materials that appear to be "equivalent" to 1/2" gypsum board, but I can't find anything similar for 5/8" Type X gypsum board.

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    I've seen commercial garages with sheet steel as ceiling (looked to be the same material you'd see as steel roofing, with ribs for structural strength, and screwed in place) but I don't know how they addressed making it a fire-rated assembly (which is the trick - 5/8 sheetrock is a component of approved fire-rated assemblies - if not assembled in accord with one of those schemes, it is not, in and of itself, magically fire-rated.) I expect there might be an approved assembly based on that sheet steel material, (perhaps with rockwool above it?), but I don't know that.
    – Ecnerwal
    Commented Jun 11, 2021 at 23:46
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    Is replacing/reworking the entire floor assembly above the garage an option in this case?
    – ThreePhaseEel
    Commented Jun 11, 2021 at 23:57
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    I use Master rib roofing tin for lots of these type situations.
    – Kris
    Commented Jun 12, 2021 at 0:59
  • houzz.com/discussions/2379418/…
    – Kris
    Commented Jun 12, 2021 at 1:35
  • I suppose a valid answer might be "you could do X with a concrete slab ceiling or Y with steel construction, but 5/8" drywall is the only thing allowed by code for wood frame, so your options are drywall or rebuild your house". But that's not the answer I'm hoping for. :)
    – CameronSS
    Commented Jun 12, 2021 at 2:38

3 Answers 3

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You could add access panels in the most useful places.

Where the wall is above, anywhere a cable turns to go up the wall would be a valid spot for an access hatch.

enter image description here

For a run of cable across to a ceiling fixture, you could put the cable run below the ceiling, or have an access every second space/joist.

No idea if this satisfies your code requirements, sorry you'll need to check that.

Note - it doesn't need to be fancy.... no need for hinges or latches. You could simply screw a metalised/metal-backed panel of drywall to the ceiling. May need to add some wood framing around the hole to provide a lip. The edges of your hatch would probably need some metal strip protection, as would the edge of the hole.

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It still may not meet code but there are suspended ceiling systems where the drop in panels are firecode sheetrock with various textures on the surface. The link has one source, but with that you can get the idea, there are more kinds out there.

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  • There definitely are rated drop in ceiling assemblies, Jack. I forgot about those. Getting one may be a trick (not going to find it at home cheapo. They are made, but they are not marketed to homeowners.)
    – Ecnerwal
    Commented Jun 12, 2021 at 12:15
  • @Ecnerwal -- problem is, the finish rating on a fire-rated suspended ceiling isn't enough AFAICT (15 mins or so on those tiles, compared to 40+ mins for 5/8" Type X)
    – ThreePhaseEel
    Commented Jun 12, 2021 at 13:12
  • I figured since he has nothing right now and hasn't since the house was built 60+ years ago, this would give him what he was looking for and give some protection while cleaning up the ceiling.... What he has now is certainly NOT code.... But to get what he is looking for will not be cheap.
    – Jack
    Commented Jun 12, 2021 at 15:28
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You could install empty junction boxes at strategic locations and conduit between them

Unused boxes are allowed to be buried, but if you start using them you'll need regular exposed face plates.

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