House Wrap Calculator
How many rolls of house wrap (weather-resistive barrier) you need for your wall area, with an overlap allowance at seams, corners and openings.
You need about 2 rolls of house wrap for 1,336 sq ft at 1,000 sq ft/roll. House wrap goes on before the siding — add ~10% for overlaps at seams, corners and openings, and confirm the roll’s stated coverage; a weather barrier is a required step, not an option.
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House wrap — the weather-resistive barrier — goes on the sheathing before the siding. It sheds any water that gets behind the cladding while letting the wall dry, and it is a required step in modern siding installation, not an optional upgrade. Planning it is simple: cover the wall area, plus a margin for the overlaps that make the barrier continuous.
This tool divides your wall area (grown by an overlap allowance) by the coverage of one roll and rounds up. Roll sizes vary — a common roll is around 1,000 sq ft, but 3 ft, 9 ft and 10 ft-wide rolls of different lengths exist — so the coverage is an input, not a fixed assumption.
Why the overlap allowance
House wrap is lapped at every horizontal seam, wrapped around corners, and returned into window and door openings. Those overlaps consume material beyond the flat wall area, so a ~10% allowance is a reasonable planning default; a house with many openings or short wall runs uses more. The manufacturer’s installation instructions specify the exact overlap at seams and penetrations — follow them, and detail the flashing at openings correctly.
Formula
rolls = ⌈ wall_area × (1 + overlap%) ÷ roll_coverage ⌉
overlap% covers the laps at seams, corners and openings; roll_coverage is the stated area of one roll. Round up to whole rolls.
Worked example
1,336 sq ft of wall, 10% overlap, 1,000 sq ft rolls:
- Area with overlap: 1,336 × 1.10 = 1,469.6 sq ft
- Rolls: 1,469.6 ÷ 1,000 = 1.47 → ⌈1.47⌉ = 2 rolls
Two rolls cover the sample house with margin to spare — the surplus handles the corner wraps and opening returns the flat-area math does not see.
Wrapping the wall correctly
- Check the roll size. Coverage ranges widely between products — read the label rather than assuming 1,000 sq ft.
- Overlap per the instructions. Horizontal and vertical laps have specified minimums; the allowance here is a planning figure, not the installed detail.
- Openings need flashing. House wrap is integrated with window and door flashing — that detail is about keeping water out, and it is a pro’s call on an existing wall.
- Wrap before siding. The barrier is a required layer under the cladding; do not skip it to save a roll.
Reference table
Labeled planning typicals — measure your actual openings. Subtract these from the gross wall + gable area.
| 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 |