The drywall between a house and garage should be 1/2 inch,
⅝” Drywall – Drywall of this thickness will usually be made in a fire resistant form since it is mostly used on ceilings and in garages.
Code usually requires 5/8'' fire code sheetrock on garage walls that have the house interior on the wall behind. That goes for the ceiling as well if the attic or whatever you call it adjoins interior space. Sheetrock is probably cheaper than any wood product and results in a good solid surface.
Heat and flame rise vertically, and so the ceiling of a garage receives more heat more rapidly. When habitable space is built over the garage, the ceiling of the garage must be protected with 5/8-in. type X gypsum board. Any walls or posts supporting that habitable space must also be protected, but only with 1/2-in.
Drywall.
The drywall between a house and garage should be 1/2 inch, fire-resistant. Garage ceilings with habitable rooms above should have 5/8 inch, fire-resistant drywall installed.
The structure of plywood is stronger than drywall, making it suitable for utility areas like laundry rooms and garages. To improve the visual appeal of plywood walls, you can use varnish or sealer, stain or paint, or decorative accents.
Drywall type – Most garages use 1/2" standard or 5/8" fire-resistant drywall, depending on local building codes. Moisture-resistant drywall helps to prevent mold in areas with high humidity. Finish level – A Level 2 finish is most common in garages.
Holds up to 65 lbs.
Of all the different types of drywall, 4-foot by 8-foot drywall that measures one half-inch thick is the most common option. Other drywall thicknesses, sizes and specialty boards may be available by special order. Get everything you need to finish your drywall project.
The short answer is that you should multiply the height and width of all wall areas, add up the totals and add another 5% to 10% to cover trim and waste. Consider a detached 22'x30' 2.5-car garage with 10-foot ceilings: 2 walls 22'x10' = 220 + 220 or 440 total square foot. 1 wall 30'x10' = 300 square foot.
There are several wall choices to consider, such as drywall, plywood, steel, or concrete. Drywall is a common material for garage walls due to its low cost and minimal effort required to install it. Plywood is another low-priced choice that is both sturdy and long-lasting.
When it's cold outside, the drywall contracts, and when it's warm outside, the drywall expands. This can cause the drywall to crack along the seams. Another reason is because of the moisture in the air. When the air is moist, it can make the drywall swell and cause it to crack.
Type X Drywall for Garages
Use Type X fire-resistant drywall for garages, as well as stairwells and areas near furnaces. While not totally impervious to fire, Type X drywall is designed to provide enhanced resistance to fire compared to basic fire-resistant drywall. Type X drywall tends to be thicker than other types.
Conclusion. In short, the garage needs to be separated from the house in case of fire, but this isn't a fire-rated assembly, nor is it a firewall. The best term for this required separation is a fire-separation wall.
Vulnerability to Moisture: Drywall's Achilles' heel in a garage setting is its susceptibility to moisture. Garages, particularly those lacking proper insulation or prone to leaks, can accumulate moisture over time. Drywall readily absorbs this moisture, leading to the formation of mold and mildew.
Does a garage need 5/8 drywall? Your local code may vary, but IBC calls for 5/8″ rock on the ceiling, and on walls common with the house. A layer of 5/8″ gyp board on the ceiling, along with the drywall on any adjacent wall in the garage attic space, also creates a one hour wall.
Whether you have a brick or uneven stone façade, or mounting a TV above a fireplace, mounting a TV can be tricky, but even more so when mounting a TV without studs. Even though drywall can support a TV up to 100 lbs., it's still brittle and the mount can require additional support.
A 4 x 8-foot sheet of standard 5/8-inch thick drywall weighs 70.4 pounds, with ultralight drywall weighing 51.2 pounds.
Walls between the residence and the attached garage, or ceilings between the garage and an attic space, must have at least 1/2-inch (12.7 mm) gypsum board on the garage side. If a habitable room is above the garage, the ceiling must be at least 5/8-inch (15.9 mm) Type X gypsum board on the garage side.
You'll likely need a permit since this project may require soil grading to avoid drainage issues. Repairing your floor may be more cost-efficient than replacing it if grading is necessary. No permit may be required to hang drywall on exposed wooden wall studs in your garage.
Fire-rated 5/8-inch drywall: Best for soundproofing and fire resistance, fire-rated 5/8-inch drywall is often used in garages.
Step 3: Follow with a vapor barrier
In the garage, like other spaces in the home, condensation results from moisture in the air. Excess condensation and humidity levels in your garage can damage your garage's foundation and cause tools, vehicles, and cabinets to rust faster.
Drywall helps regulate temperature, improve soundproofing, and make the garage easier to clean and maintain. It can also add value to your property, which is especially important if you're considering selling your home in the future.