What is likely behind this drywall in my garage?

Question

I am planning a summer project to renovate my garage. I want to insulate and install 3/4 ply on all of the walls and lay new race deck flooring.

The garage still has partial drywall from the initial build:

Can anyone tell me what is likely to be under this and if they have any pictures of similar situations?

Ideally, my goal is to open all of this, like the front portion of the garage, and only install plywood on all the walls. I then plan to paint the entire garage white. This is what I am going for:

I may just decide to replace the roof drywall with plywood as well if it's an eye sore but I prefer not to if possible.

Answer 1

Typically the reason you put drywall in a garage is to provide a fire resistant separation between the garage and an attached house (living space). Also keep in mind that constructing a house is a balance of cost vs. code compliance, safety and the desires of the homeowners.

So if that huge area was drywalled, then that was probably the easiest and cheapest way of getting the fire barrier. Ask yourself why they drywalled a large boxy area instead of just the back wall. That will give you some idea what might be in there.

Also, drywall is easy to repair. Just cut it open, but be prepared to fix it immediately, if only temporarily. Again, drywall in a garage provides an important fire barrier between the garage and living space.

Answer 2

Longneck posted essentially what I'd have said. I'll add a few clarifying thoughts to that answer.

• This is indeed a firewall, and it was installed in that location either because there's habitable space above or because this was the most convenient place to get a continuous barrier all the way to the roof sheathing. That can be challenging.
• You have a hip roof, and behind the vertical plane is probably the first common truss in a series. It provided good backing for drywall, so it was used. Judging by the screw pattern it was either a "gable truss", with integrated studs, or the carpenters added them to a more conventional webbed truss.
• If you open that area as planned you'll need to reestablish that fire barrier. You may be able to run up a different truss, or you may need to build a wall over the garage/house partition wall. That's your main goal--to determine whether and how that might be done.
• I would zip a hole in the vertical, above any insulation that might be present, and have a look. If you cleanly cut an opening you can easily reinstall the piece as a patch. Either cut over the studs to retain backing, or cut out between the studs and float new backing to reinstall. Backing does not need to attach to existing framing. Technically the patch should be taped to reestablish its fire rating, but it's a minor concern in the grand scheme of things.

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Unsolicited advice: I would not paint your ceiling space white. For one thing it'll take an obscene amount of paint to cover all those framing members thoroughly from all visible angles. For another, it'll look great for about six months, then it'll start to get dingy from exhaust residue, dust, and webs. That only gets worse with time.

I would consider a beige or light tan, which will mask dirt and thin spots in the framing.