Standard door, window & garage-door area deductions
Typical published planning values — NOT a certified spec or professional advice. Coverage and exposure vary by product and installation; confirm on the manufacturer’s installation instructions and stated coverage. Moisture, flashing, sheathing and pre-1978 lead paint on old siding are a pro’s call — follow the manufacturer’s instructions, local code and the EPA RRP rule and hire a certified firm; lead-paint abatement, structural and moisture repairs and code certification are not engineered here.
Net siding area is the gross wall and gable area you measured minus the openings. These are the LABELED standard deductions — a door about 21 sq ft (3 × 7), a window about 15 sq ft, a patio door about 40, a single garage door about 63 (9 × 7) and a double garage door about 112 (16 × 7) — a planning convention you should adjust to your actual openings. Use them with the square-footage calculator and the how-much-siding calculator.
| Opening | Deduct (sq ft) |
|---|---|
| Standard door (3 × 7) | 21 |
| Standard window | 15 |
| Patio / sliding-glass door | 40 |
| Single garage door (9 × 7) | 63 |
| Double garage door (16 × 7) | 112 |
LABELED planning typicals — measure your actual openings. Deduct doors, windows and garage doors from the gross wall + gable area to get the net siding area; trimmed openings and small windows vary.