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Tyvek HomeWrap: the vapour-permeable wall wrap

Tyvek HomeWrap is DuPont's spunbonded vapour-permeable wall wrap, AS/NZS 4200 Class 4 and non-reflective. A premium secondary weather barrier for cool-climate builds.

By Chalkline. Last updated 25 May 2026. Verified 25 May 2026.

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Tyvek HomeWrap is DuPont’s spunbonded high-density-polyethylene wall wrap, a vapour-permeable, non-reflective pliable membrane used as a secondary weather barrier behind cladding. It is the best-known of the vapour-open wall wraps, sitting in a different category from foil sarking: no reflective face, very high vapour permeance.

What it does

Tyvek wraps the frame under the cladding and does two jobs at once: it resists liquid water getting into the wall from outside, while letting water vapour pass out of the wall cavity, so moisture that gets into the wall can dry outward rather than being trapped. It also acts as an air barrier, which matters on tightly sealed builds.

Under AS/NZS 4200.1:2017 it is a Class 4 vapour permeance membrane (greater than 1.14 µg/N·s), the most vapour-open class, and it is non-reflective (it has no foil face, so it adds no reflective insulation value). For more on the permeance scale, see vapour permeance.

Tyvek vs foil sarking

The choice is about the job:

  • Foil sarking: reflective face, lower vapour permeance. Chosen where a radiant/reflective barrier is wanted.
  • Tyvek (vapour-permeable wrap): non-reflective, very high permeance. Chosen where drying-out and condensation management matter, particularly cooler climates and tightly air-sealed builds where trapped moisture is the risk the NCC’s condensation provisions target.

They are not interchangeable: a vapour-permeable wrap will not give you a reflective barrier, and a low-permeance foil can trap moisture in a cool-climate wall.

For a builder

  • It is a secondary barrier, not the cladding. Tyvek manages water and vapour behind the cladding; it does not replace correct flashing and cladding detailing.
  • Use it where vapour-open matters. Cool-climate walls and airtight builds are where the high permeance earns its (premium) price; in those walls a vapour-closed membrane is a condensation risk.
  • Install per the guide. Laps, the printed overlap lines, and the proprietary tape are part of the system; a poorly lapped or untaped wrap leaks air and water.

Also known as: Tyvek, Tyvek wall wrap, DuPont Tyvek HomeWrap.

See also

Last updated: 2026-05-25. Verified: 2026-05-25. Quarterly review for currency.

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