House Wrap Rolls Calculator

Review the takeoff

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Project preset:

Start from a small house, two-story shell, garage, or known-area takeoff.

Unit system:

Choose the units used in the form, tables, chart, and exports.

Measurement basis:

Pick the fastest reliable way to enter the exterior wall takeoff.

House length:

Enter the longer or first footprint dimension.

House width:

Enter the shorter or second footprint dimension.

Total wall run:

Use the combined exterior wall length around the shell.

Wrap height:

Use the average vertical height that will receive wrap.

Known gross wrap area:

Enter the gross area from drawings, a siding takeoff, or field notes.

Reference wall run:

Enter the approximate exterior wall run behind the known area takeoff.

Reference wrap height:

Use the average vertical wrap height from lower start to upper stop.

Gable or bump-out allowance:

Keep zero for a flat rectangular takeoff, or add extra gross wrap area.

Roll size:

Choose the roll label used for purchase rounding and course planning.

Custom roll width:

Roll width controls horizontal courses and lap count.

Custom roll length:

Roll length controls nominal square coverage and vertical seam estimates.

Exterior doors:

Count exterior door openings that need perimeter flashing.

doors

Windows:

Count window openings that need wrap cuts and flashing tape.

windows

Overlap and cutting allowance: {{ formatPercent(waste_percent, 0) }}

Use higher values for cut-up elevations, many openings, or low confidence field measurements.

Seam taping:

Choose whether the estimate includes horizontal lap tape in addition to vertical seams.

Horizontal lap:

Used for course count, lap length, and audit rows.

Vertical seam lap:

Reported for installation checks and seam waste context.

Fastener spacing:

Used with stud spacing to estimate cap nails or cap staples.

Stud or fastening-line spacing:

A 16 inch value gives a conservative fastener estimate for many framed walls.

Seam tape roll length:

Used to round seam tape to whole rolls.

Flashing tape roll length:

Opening perimeter plus waste is rounded to this roll length.

Fasteners per box:

Fastener total is rounded to whole boxes when this value is positive.

per box

Typical door size:

Enter a typical exterior rough opening width and height.

{{ lengthUnit }} wide

Typical door height:

Keep aligned with the typical exterior door rough opening.

Typical window size:

Enter a typical window rough opening width and height.

{{ lengthUnit }} wide

Typical window height:

Keep aligned with the typical window rough opening.

Tape waste allowance:

Applied to seam tape and flashing tape before roll rounding.

Expected exposed days:

Flag long delays before siding, cladding, or exterior finish installation.

days

Price per wrap roll:

Optional material pricing; zero leaves quantity-only results.

Price per seam tape roll:

Applied to the rounded seam tape roll count.

Price per flashing tape roll:

Applied to the rounded flashing tape roll count.

Price per fastener box:

Applied to rounded fastener boxes.

Takeoff item	Estimate	Basis	Copy
{{ row.item }}	{{ row.estimate }}	{{ row.basis }}

Planning signal	Status	Evidence	Next check	Copy
{{ row.signal }}	{{ row.status }}	{{ row.evidence }}	{{ row.action }}

Scenario	Adjusted area	Rolls	Spare area	Use case	Copy
{{ row.scenario }}	{{ row.adjustedArea }}	{{ row.rolls }}	{{ row.spareArea }}	{{ row.useCase }}

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House wrap is a water-resistive barrier layer that sits behind exterior cladding and over wall sheathing. A useful takeoff starts with the exterior wall area, then adds enough material for laps, cutting waste, corners, gables, and field mistakes without confusing roll coverage with net wall area.

Openings change the order of the estimate. Window and door cutouts reduce visible wrap area, but they usually increase detailing time because every opening still needs flashing tape and careful lapping. Course count also matters: a narrow roll on a tall wall can create horizontal laps that need more seam attention than a wider roll on the same wall.

House wrap wall area, laps, opening details, and roll coverage — Roll count comes from adjusted gross wall area, while tape and fasteners are driven by courses, seams, openings, and spacing.

This calculator turns a wall takeoff into purchased rolls, spare square footage, seam tape rolls, flashing tape rolls, cap fastener boxes, waste scenarios, and optional material cost. It supports footprint, wall-run, and known-area workflows so the estimate can follow the information available on the job.

How to Use This Tool:

Choose the project preset closest to the building, then select imperial or metric inputs.
Pick the measurement basis. Use footprint when length and width are known, wall run when you already measured exterior perimeter, or known gross wrap area when a siding or sheathing takeoff is available.
Enter wall height and any gable or bump-out allowance. The gross area should describe sheathed exterior wall area before waste.
Select the roll size. If the supplier roll is not listed, choose the custom roll and enter width and length.
Add exterior doors and windows so the opening area and flashing tape allowance reflect the job.
Set overlap and cutting allowance. Keep a practical buffer for corners, laps, damaged sheets, and layout mistakes.
Choose the seam taping scope, then review the advanced lap, fastener, tape roll, exposure, and price fields only when they matter for the estimate.

After calculation, compare the roll count with the spare-area warning and waste scenarios before ordering. A small spare amount can disappear quickly when wall height, gables, or course layout are off by a small amount.

Interpreting Results:

Rolls needed is rounded up from adjusted coverage, so it is the purchase quantity rather than a fractional use value. Purchased area shows the square footage bought after rounding to whole rolls, and Spare area shows the unused buffer after the selected waste allowance.

House wrap result interpretation
Result	What drives it	How to use it
`Adjusted area`	Gross wall area plus the selected overlap and cutting allowance.	Use this to compare roll sizes or waste assumptions.
`Seam tape rolls`	Course count, wall run, roll length, tape mode, and tape waste.	Check this closely when a tall wall needs multiple horizontal courses.
`Flashing tape rolls`	Door and window perimeter, typical opening sizes, and tape waste.	Use it as an allowance, then adjust for unusually large or detailed openings.
`Fastener boxes`	Wall run, wrap height, fastening-line spacing, vertical spacing, and box count.	Compare against product instructions and local wind or exposure requirements.
`Material cost`	Optional prices for wrap, seam tape, flashing tape, and fasteners.	Use as a material-only check, not a full installed bid.

Warnings point to estimates that deserve review, such as low waste allowance, very small spare area, long exposure time before cladding, missing horizontal seam tape on multi-course work, or opening area that is unusually large compared with wall area.

Technical Details:

The model first converts all entries to feet and square feet. Footprint mode derives wall run from building length and width, wall-run mode uses the entered perimeter, and known-area mode uses the entered gross wrap area while still using the reference run and height for seam and fastener estimates.

Formula Core:

\begin{array}{lcl} A_{gross} & = & (wallRun \times wallHeight) + A_{gable} \\ A_{adjusted} & = & A_{gross} \times (1 + \frac{wastePct}{100}) \\ rolls & = & ⌈ \frac{A_{adjusted}}{A_{roll}} ⌉ \\ spareArea & = & (rolls \times A_{roll}) - A_{adjusted} \end{array}

The tool treats roll coverage as roll width x roll length. It estimates courses from the roll width minus the horizontal lap, with a minimum effective lift to prevent impossible course spacing.

House wrap secondary formulas
Quantity	Simplified formula	Notes
Courses	`ceil(wall height / effective course lift)`	Effective lift is roll width minus horizontal lap.
Vertical seam length	`seams per course x courses x covered course height`	Used when vertical seams are taped.
Horizontal lap length	`max(0, courses - 1) x wall run`	Used when all seams are taped.
Flashing tape length	`opening perimeter x (1 + tape waste %)`	Opening perimeter comes from door and window count and typical sizes.
Fasteners	`fastening lines x fasteners per line`	Rounded up to whole boxes.

The waste scenarios recalculate the adjusted area and whole-roll count at low, selected, and high allowance values. This helps show whether the estimate is stable or whether one extra roll is likely to be needed if field waste rises.

Limitations and Accuracy:

House wrap ordering depends on product instructions, local code, cladding schedule, weather exposure, crew practice, and unusual geometry. The calculator does not replace manufacturer installation guidance, building-code review, or a detailed wall elevation takeoff.

For jobs with many jogs, porches, intersecting roofs, large wall penetrations, high-wind exposure, or long weather exposure before cladding, review the result with the selected product instructions and add project-specific contingency.

Worked Examples:

Footprint estimate. A rectangular house with a 42 ft by 30 ft footprint and 9 ft wrap height has a wall run of 144 ft and a base wall area of 1,296 sq ft before gable allowance and waste. With a 12% allowance, the adjusted area is 1,451.5 sq ft, so a 9 ft x 100 ft roll layout needs whole-roll rounding.

Opening-heavy wall set. A project with many windows may not reduce roll count because rolls are bought in large coverage blocks, but it can increase flashing tape because tape follows opening perimeter rather than net wall area.

Multi-course wrap. A tall wall using a narrow roll can create horizontal laps. If seam tape is set to vertical seams only, review the warning and product instructions before relying on the seam tape count.

FAQ:

Should I subtract every window and door from the roll estimate?

Not usually. Openings reduce net covered area, but rolls are bought in whole lengths and cutouts still create waste and flashing work. Use opening counts mainly to size flashing tape and to flag unusual opening density.

Why does the estimate show spare area?

Spare area is the difference between purchased roll coverage and adjusted area. It is a buffer after rounding, not a guarantee that every offcut will be usable.

What waste allowance should I start with?

A moderate allowance around the default is suitable for a first pass on ordinary walls. Increase it for complex shapes, inexperienced installation, windy conditions, or many short wall segments.

Does this include labor or siding material?

No. The optional cost section is a material-only estimate for wrap, seam tape, flashing tape, and fasteners.

Glossary:

Water-resistive barrier: A layer behind exterior cladding that helps shed bulk water away from sheathing.
Wall run: The total exterior wall length used for area, seam, and fastener estimates.
Course: One horizontal band of wrap around the wall.
Lap: The overlap between adjacent pieces of wrap.
Adjusted area: Gross wall area increased by the selected overlap and cutting allowance.
Spare area: Purchased roll coverage remaining after adjusted area is subtracted.

References:

International Residential Code, Section R703.2 Water-resistive barrier, International Code Council.
DuPont Tyvek Water-Resistive and Air Barriers Residing Installation Guidelines, DuPont Performance Building Solutions.