Estimate how many squares of siding or cladding, starter strips, and trim you need for your project.
Step 1: Calculate your total wall area (length × height for each wall, added together).
Step 2: Measure and enter the total area of all openings (windows and doors).
Step 3: Add any gable area if your siding extends into the gable.
Step 4: Select your siding type and adjust the waste percentage (10% is standard, 15% for complex layouts).
Results are given in "squares" (1 square = 100 sq ft / 9.29 sq m) which is the standard ordering unit.
A square is a unit of measurement equal to 100 square feet (9.29 sq m) of coverage. Siding is typically sold and priced per square.
10% waste is standard for simple rectangular walls. Add 15% for walls with many windows, dormers, or irregular shapes. Diagonal installations may need 20%.
Gable area = (base × height) / 2. Measure the width at the base and the height from the top of the wall to the ridge peak.
Most timber and composite cladding is fixed horizontally, which sheds water well and is quickest to install. Vertical cladding gives a contemporary look but usually needs battens both ways behind it.
Yes — leave a ventilated cavity of around 25 mm (1 in) behind the cladding on battens. This lets the timber dry out on both sides and helps prevent damp and rot.
