House wrap is a synthetic, water-resistant sheet material installed over the wall sheathing before siding goes on, providing a critical secondary barrier against water intrusion while still allowing water vapor to pass through, helping the wall assembly manage moisture in both directions.
This dual capability, blocking liquid water while permitting vapor transmission, distinguishes house wrap from a simple plastic sheet, since a wall assembly needs to both resist bulk water intrusion and still allow any trapped moisture within the wall to eventually dry out.
Proper house wrap installation, including correctly overlapped seams and careful taping at all seams and penetrations, significantly affects how well this material actually performs its intended protective function.
What Does House Wrap Involve?
- A synthetic, water-resistant, vapor-permeable sheet material
- Installation over wall sheathing before siding
- Overlapped seams sealed with compatible tape
- Careful integration with window and door flashing
Why Is House Wrap Important?
Serving as the critical secondary defense behind whatever siding material a home uses, house wrap catches and directs away any water that manages to penetrate through or behind the siding, protecting the sheathing and structural framing from moisture damage that could otherwise go undetected for years. This backup protective function makes house wrap essential regardless of how well the exterior siding itself performs.
Because house wrap seams and penetrations represent the most common failure points in this system, using manufacturer-recommended tape and following proper installation sequencing, including correct overlap direction that shingles water downward and outward, matters significantly more than the specific brand of house wrap chosen. This attention to installation quality often matters more than the specific product brand selected.
House Wrap vs. Weather-Resistive Barrier
House wrap is a specific, common product type used to achieve weather resistance. Weather-resistive barrier is the broader functional category, which house wrap fulfills, though other materials like certain rigid foam products can also serve this same fundamental protective role.