Calculating the amount of siding that your home needs is an essential part of planning a siding replacement project, particularly in preparing a written estimate. While your siding and roofing installation contractor does the actual math, knowing how to calculate the required siding can help you make informed decisions about your project. In this blog, Advanced Roofing shares a look at how the amount of material needed for siding replacement is calculated.
Wall Square Footage
First, the wall square footage must be calculated. Rectangular walls are the easiest to measure, since it’s just a matter of multiplying the height against the width. Areas such as gables and irregular walls are more complicated to compute. All openings such as doors and windows must also be measured. Subtract the combined areas of all the openings from the wall square footage and you now have the wall area that requires siding.
Lineal Area Factor
The lineal area factor measures the length of siding needed for the exterior. Siding doesn’t lay flat like wallpaper and overlaps and dressing must be factored in. Let’s say you have chosen an 8-inch wide beveled siding, with an exposed face of 6.5 inches (after 0.5-inch dress and 1 inch overlap). Lineal area factor would then be 12 inches (1 foot) divided by 6.5 equals 1
Total Required Siding
To calculate the amount of required siding, multiply the square footage against the lineal area factor. Let’s say you ended up with 220 square feet of wall square footage, after subtracting the openings. Multiply this by our previous lineal area factor 1.85 and you have 407 square feet of siding. Add a bit of headroom for trimmings and errors and you will need 447.7 square feet of siding for your home. Calculating cedar shakes and shingles are a bit more complicated and should be left to professionals.
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