House wrap serves as a critical component in modern building construction, protecting structures from water damage and contributing to energy efficiency. Installed between the sheathing and siding, it blocks wind-driven rain while allowing interior moisture vapor to escape. Proper installation, adhering to best practices, is essential to realize these benefits and avoid costly repairs. This article details effective house wrap installation techniques based on available documentation.
The Importance of House Wrap
Without a house wrap barrier, air leaks can account for up to 30% of a home’s energy loss. Modern building codes increasingly require continuous wraps with taped seams to ensure a comprehensive moisture barrier. Ignoring proper installation can lead to rot, mold, peeling finishes, and ultimately, expensive callbacks or moisture damage. The function of house wrap is to create a permeable envelope that reduces energy costs, maintains insulation value, and prolongs the life of the siding.
Selecting the Right House Wrap
Not all house wraps are created equal. The “perm” rate, a measure of how quickly water vapor escapes, is a crucial factor. Low-cost wraps often have a perm rating of 8 to 12, which can be problematic, particularly in colder climates or older homes lacking other moisture barriers. Vapor can become trapped, condense into frost, and then melt, leading to damp sheathing and soggy insulation. Choosing a high-perm product, such as Tyvek, with a rating around 54, is recommended to maintain a dry and energy-efficient wall assembly.
Preparation and Handling
Cutting full rolls of house wrap down to more manageable sizes can significantly improve the installation process, especially on windy days. A circular saw can be used for this purpose, though it may not cut completely through a full roll on the first pass; twisting the roll can complete the cut. Smaller rolls facilitate more tape on horizontal seams, offsetting the cost of the extra tape with increased labor efficiency. Prior to installation, wood siding should be primed or sealed on the back to prevent condensation from wicking into the wood and causing paint to peel.
Installation Techniques
Several techniques contribute to a successful house wrap installation.
Tack, Straighten, and Fasten
When starting a new course of house wrap, avoid pinning the entire vertical edge immediately. Instead, tack a few capped fasteners in the center, roll out several feet, slide the sheet up or down to achieve proper alignment, and then secure the rest. This method minimizes wrinkles, which can trap water and compromise the barrier.
Overlap and Sealing
Treat house wrap like shingles, overlapping each new sheet over the one below by at least 6 inches, and increasing to 8 inches in high-wind zones. Proper sealing of seams, combined with substantial overlap, directs water securely outside and prevents blow-backs.
Addressing Wall Penetrations
Every penetration in the wall, such as pipes or wiring, requires careful sealing with tape. To address a pipe, cut around it closely, making two angled cuts up and away from the top. Tape the flap up to keep it out of the way, then tape the pipe to the wall, starting at the bottom. Finally, fold down the flap and tape it up.
Cutting for Openings
Rather than cutting out window openings directly in the house wrap, a different approach is recommended. This method meets the requirements of most window manufacturers and is generally favored by inspectors. Detailed instructions for this process are available in separate resources on window installation.
Simple Cutting Trick
A sharp utility knife is effective for cutting house wrap, but the last inch of a small cutoff can crumple the roll. To avoid this, start the cut in the roll’s middle, slice one half, leave a 1-inch hinge, and then cut the other half. Tearing along the hinge creates a smooth edge free of wrinkles.
Working with Subcontractors
If acting as a general contractor, ensure an extra roll of house wrap is available on the job site for framers, electricians, and other subcontractors who may need to attach objects to the wall. Providing clear instructions for installation is also crucial. Common areas requiring house wrap behind attachments include soffit stringers, trim boards, and electrical meters.
Environmental Considerations
House wrap can be installed in cold or wet weather, provided the sheathing remains dry and winds are below 15 mph. Under harsh conditions, using low-temperature tapes, shorter lengths of wrap, and additional cap fasteners can prevent wrinkling and ensure good adhesion.
Exposure Limits
Most house wrap brands allow for 30 to 180 days of exposure before siding installation. However, ultraviolet light degrades the fibers and loosens fasteners over time. If delays are anticipated, re-inspect the wrap, retape seams, and refasten as needed to maintain the integrity of the barrier.
Frequently Asked Questions
The documentation addresses common questions regarding house wrap installation. These include guidance on installation in cold or wet weather and the maximum allowable exposure time before siding is applied. Consulting the manufacturer’s datasheet is recommended for specific exposure limits.
Conclusion
Proper house wrap installation is a vital step in building a durable, energy-efficient, and moisture-resistant structure. Selecting a high-perm product, employing careful installation techniques, and addressing potential issues proactively will contribute to a long-lasting and comfortable building envelope. Attention to detail, particularly regarding overlaps, sealing, and handling penetrations, is paramount to achieving optimal performance.