Garage Drywall Code Requirements

The four rows of Table R302.6

• From the dwelling unit and attics: not less than 1/2 in gypsum board or equivalent, applied to the garage side.
• From portions of the dwelling unit above the garage: not less than 5/8 in type X gypsum board or equivalent.
• Structure supporting floor/ceiling assemblies used for that separation: not less than 1/2 in gypsum board or equivalent.
• Garages less than 3 ft from a dwelling unit on the same lot: not less than 1/2 in gypsum board or equivalent on the interior side of exterior walls within that area.

Section R302.6 also says the wall rows do not apply to garage walls that are perpendicular to the adjacent dwelling unit wall. In a typical attached garage that means only the wall you share with the house is required, plus the ceiling, plus any walls that carry a room above.

What type of drywall for a garage ceiling?

It depends on what is above it. Under a bedroom, bonus room or any other part of the house, the ceiling needs 5/8 in type X. Under an attic with no floor, 1/2 in gypsum board on the garage side meets the model code. A detached garage with nothing above has no ceiling requirement at all under Table R302.6.

The 2024 edition widened the type X trigger. The 2021 table said habitable rooms above the garage; 2024 says portions of the dwelling unit above the garage, so a storage room or bathroom over the garage now calls for type X too. The checker lets you switch editions to see the difference.

Table R702.3.5 sets the fastening for a type X garage ceiling beneath habitable rooms: board perpendicular to the framing, framing at most 24 in on center, and fasteners every 6 in, using 1-7/8 in galvanized nails or equivalent drywall screws.

The door between the garage and the house

Section R302.5.1 covers the opening in the separation. The door must be solid wood or solid or honeycomb-core steel at least 1-3/8 in thick, or a 20-minute fire-rated door, and it must be self-latching with a self-closing or automatic-closing device. No opening is allowed from the garage directly into a room used for sleeping. Ducts in the garage or through the separation must be at least No. 26 gage sheet steel with no openings into the garage (R302.5.2).

Check your local code

This page explains the model International Residential Code. Your state, county or city may adopt a different edition or amend it, and some require 5/8 in type X on every garage surface. Check your local code with the building department before you buy board.