The amount of paint needed to cover a two-car garage will vary based on several factors. The homeowner will need to calculate the square footage of the surface that will be painted and research the covering capacity of the paint being chosen. Because garages are usually four-sided rectangular structures, the process is not difficult.
Calculating Paint Needs for a Garage
Calculate the surface area of the exterior walls of the garage. Start with walls without peaks. The surface area is the length of the wall times the height, measured in feet. A garage wall 24 feet long and seven feet high would have an area of 168 square feet. Subtract large openings, like the garage door, by using the same method to determine the area of the garage door. Small openings like windows and walk-in doors can be ignored when estimating the paint needs for the building.
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Walls with a peak are a little more difficult. Start by measuring the width of the wall and the height of the point where the roof starts. Multiply these two numbers to determine the area of the lower part of the wall. Measure the width of the wall at the point where the roof starts and the height of the peak above an imaginary line running between the lower points of the roof on each side. Multiply these two numbers and divide by two.
Example of Calculating Paint for a Two Car Garage
For example, for the north wall: 24 feet long by 8 feet high equals 192 square feet (24 x 8 = 192). The south wall is also 24 feet long by 8 feet high, less 16 foot wide by 7 foot high for the garage door, equaling 80 square feet. (24 x 8)-(16 x 7)= 80.
For the east wall: 20 feet wide and 8 feet high at the bottom of the roof, with the peak of the roof being four feet high, measures 200 square feet. (20 x 8) + ((20 x 4)/2)= 200. The west wall is identical to the east wall.
Add all the walls together and the total surface area of the garage to be painted is 672 square feet. If the paint chosen covers 400 square feet, for example, the project would use most of two gallons. Most paints list an expected coverage per gallon; this is an estimate. If the wood is particularly dry, it will absorb the paint more readily and require more paint to cover the entire surface.