House Wrap / Weather Barrier Calculator

A house wrap calculator returns the rolls of weather barrier needed to cover a home's exterior walls. It adds a seam overlap allowance (10% by default) to the total wall area, then divides by the coverage of one roll and rounds up to whole rolls.

Last reviewed September 2026Method & sources Report an error

Rolls Needed

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House Wrap / Weather Barrier3 rolls

Breakdown
Rolls Needed	3
Area with Seam Overlap Applied	1,980.0 sq ft

How to Calculate House Wrap / Weather Barrier

House wrap goes on shingle-style, working up the wall so each course overlaps the one below it by several inches. Any water that reaches the surface drains outward over the seam below instead of finding a way behind it. Vertical seams get the same overlap-and-tape treatment, which is why the wrap needed runs somewhat ahead of the wall's raw square footage. This calculator adds that overlap allowance to the total wall area, divides by a single roll's coverage, and rounds up to a whole roll.

Example: 1,800 sq ft total wall area, using rolls that cover 900 sq ft each

An 1,800 sq ft total wall area, using rolls that cover 900 sq ft each, with a 10% overlap allowance: 1. Area with overlap: 1,800 × 1.10 = 1,980 sq ft 2. Rolls needed: ceil(1,980 ÷ 900) = 3 That house needs 3 rolls of house wrap.

House Wrap / Weather Barrier: Compare Scenarios

Scenario	Rolls Needed	Area with Seam Overlap Applied
Small (800 sq ft addition)	1	880.0 sq ft
Medium (1,800 sq ft single-story home)	3	1,980.0 sq ft
Large (3,600 sq ft two-story home)	5	3,960.0 sq ft

What Is House Wrap / Weather Barrier?

House wrap is a water-resistive barrier that goes directly over the wall sheathing, under the siding. It sheds bulk water (rain, wind-driven moisture) while still letting water vapor from inside the wall escape outward. That is a different job from a vapor barrier or the siding itself. This calculator converts a house's total exterior wall area into the rolls needed to cover it, with the shingle-style overlap a proper installation needs already built into the total.

House Wrap / Weather Barrier: Pros and Cons

Pros

Applies a seam overlap allowance automatically, rather than assuming the wrap exactly matches the wall's raw area
Roll coverage is adjustable, since house wrap and other weather barrier products come in different roll widths and lengths
A straightforward starting point before ordering seam tape and window flashing separately

Cons

Doesn't include seam tape, window/door flashing, or fastener caps, which every installation also needs on top of the wrap itself
A wall with many windows, doors, and other penetrations needs extra cutting and patching around each one, which this general area-based estimate doesn't individually account for
Doesn't cover a rigid or fluid-applied weather-resistive barrier system, which uses a completely different coverage calculation than a rolled sheet product

House Wrap / Weather Barrier: What a Pro Checks

Overlap every horizontal seam at least 6 in. and tape it, along with every vertical seam and every penetration. Most manufacturers specify this for the barrier to perform as tested.
Run the wrap continuously over rough openings first, then cut it in an X pattern and fold the flaps back before taping. Don't cut window and door openings out ahead of time.
Budget seam tape, flashing tape, and fastener caps as their own line item. This estimate covers the wrap itself, not the accessories every installation also needs.

Frequently Asked Questions

How much house wrap do I need for my house?

Add a seam overlap allowance (commonly 10%) to your total exterior wall area, then divide by your specific product's roll coverage and round up. An 1,800 sq ft wall area with 900 sq ft rolls needs 3 rolls.

How much should house wrap seams overlap?

Commonly at least 6 in. at horizontal seams, sealed with seam tape rated for the product. Check your specific manufacturer's installation instructions, since minimum overlap and taping requirements vary by brand.

What's the difference between house wrap and a vapor barrier?

House wrap is a weather-resistive barrier. It blocks bulk liquid water from reaching the sheathing while still letting water vapor pass through so the wall can dry. A vapor barrier (like polyethylene sheeting) blocks vapor movement entirely and serves a different purpose, typically on the warm-in-winter side of insulation, not under the siding.

Does house wrap go over or around windows and doors?

It's typically run continuously over the rough openings first, then cut in an X pattern at each opening and folded back, with flashing tape applied afterward. It isn't cut out and skipped around openings ahead of time.

Do I need to tape every house wrap seam?

Yes. Most manufacturers specify taping every horizontal and vertical seam, plus around every penetration, for the barrier to perform as tested. An untaped overlap alone is more likely to let water find a path through at the seam.

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