How to Choose the Best Housewrap
Building tighter, energy-efficient homes has come with both benefits and risks. As we’ve seen over time, increased airtightness improves energy efficiency, but it also risked producing mold and rot without the proper control of moisture vapor. The key to solving this issue is to allow moisture to dry out. A housewrap (also known as a water-resistive barrier or WRB) can be an important component to keeping a house standing for generations without mold growth or rot. When picking amongst good, better, and best housewraps, this guide will help you decide which housewraps provide the best system for your price point, climate, and house design.
How to Choose Housewraps
One of the keys to the appropriate housewrap for a home is knowing how the structure and climate will play a role in exposing (or reducing) the amount of rainwater that hits the walls of the building. Certain types of environments and design consideration will be the most important components to look at when picking between housewraps. For example, a home with 2-foot roof overhangs and little annual rainfall requires less water protection, which means your housewrap shouldn’t need as much protection as a home with no overhangs that sees a ton of rain annually. Paying attention to design elements like roof overhangs, the roof pitch, and wall height will allow you to understand how much water will hit the structure, and what the exposure will mean for infiltration and drying.
Other good rules-of-thumb: Whatever you choose, pick something that’s durable, above code-compliant options (like building paper), and take care when installing the product. Housewraps that tear easily, or are pin-pricked and easy to see through when held up to light are signs that the WRB won’t hold up very well to water or construction damage. It’s best to err on the side of more than less, especially since a failed wrap system can call for more work, repairs, callbacks, and even a loss.
A good housewrap should be paired with a structure that’s protecting the walls of the home through good design, or in an environment that doesn’t receive much rain (less than 30 inches). For example, the walls of a single-story house with 2-foot overhangs will get comparably less water. A housewrap suitable for this type of structure, therefore, would be something like a small-gap housewrap like Tyvek Drainwrap: the textured surface allows for water to drain out and away. Overall, good housewraps must allow for water to get out easily, so the sheathing can dry quickly without mishaps. Or, on the flip side, if the wall is in a climate that doesn’t receive much rain, the housewrap will not be too taxed and the building will be able to dry reasonably well on its own.
Better housewraps provide more protection with a rainscreen, which holds the siding away from the housewrap and the sheathing underneath it. In addition, they add not just another layer of protection but improve ventilation. This is a good option especially for houses made with reservior cladding which tends to suck up water (such as stucco, stone, or brick). DELTA®-DRY STUCCO & STONE by Dörken is a great option since it provides an air gap between itself and the stucco, and between itself and the sheathing for improved ventilation and drainage.
The best housewraps are actually not referred to as housewraps; they are called an air and moisture barrier. They provide the ultimate protection to walls, and go above and beyond many good and better products as well as building code requirements. Air and moisture barriers have the added ability to air-seal the wall while also protecting it from moisture, which drastically reduces water getting in.
For example, DELTA®-VENT SA by Dörken is a peel-and-stick, fully adhered system that is highly rated for its ability to keep out water. The double-stick layer at the edges of the material creates an airtight seal on all the overlapping seams for tightly air-sealing the wall.
This eliminates many installation errors frequently found with good and better housewraps. These problems include poorly taping or not taping the seams at all, using improper fasteners as well as tears and blow offs caused by wind. All of these reduce the effectiveness of good and better wraps by allowing moisture to reach the interior walls. They also allow cold air into the house that wastes energy and creates drafts.
DELTA®-VENT SA is also highly vapor permeable allowing for moisture vapor from inside the house, to escape and allowing the walls to dry rapidly.
A high-performance air and moisture barrier is the best option for homes that need a high degree of protection, such as a house with coastal or annual rainfall of over 40 inches. With that amount of exposure, getting the best barrier will do wonders to keep the interior walls dry and to prevent rot.
Overall, picking between good, better, and best housewrap options is worth the time and energy to study, especially if you want to avoid any reinstallation or issues with mold or rot. By paying attention to the design of the home and its climate for its location, you can choose a housewrap or barrier suitable for your project.