If you’re unsure how much coating you’ll need, let these steps be your guide:
- Determine the square footage below the roofline. To do this, add the widths of the four sides of your house, then multiply that number by your house’s height below the roofline. In our example: 60 + 60 + 20 + 20 = 160 x 10 = 1,600 square feet below the roofline.
- Determine the square footage above the roofline. For each pitched roof or gable, multiply the height of the peak (measuring from the roof base line) by one-half the length of the roof base line. In our example: 6 x 10 = 60 x 2 peaks = 120 square feet above the roofline.
- To determine the total area to be coated, add your answers from steps 1 and 2. In our example: 1,600 + 120 = 1,720 square feet.
- Subtract 21 square feet per door and 15 square feet per single window. In our example, with three single windows, one double window and one door: 1,720 – 75 (windows) = 1,645 – 21 (door) = 1,624 square feet.
- To estimate the number of gallons of coating you’ll need for one coat, choose the coating type and suggested square foot coverage rates for that coating. Divide the total area by suggested square foot coverage. For example: 2500 square feet of wall area would require 8.34 gallons of coating at a square foot coverage rate of 300 feet per gallon.
- For trim, multiply the number of doors by 21 and the number of windows by 15. Divide by suggested square foot coverage rates for the selected product. This will give you the approximate total gallons required for your project.