Builder Jeff Fava experienced a huge storm near one of his custom home construction sites. The wind blew through the home's doorway and ripped out several hundred square feet of insulation. It tore two telephone poles in half. But the weather-resistive barrier built into the house's Nautilus wall sheathing remained intact.
"With [housewrap], we would have had to replace every piece of it," speculates Fava, senior partner of Associated Builders, which operates around Chattanooga, Tenn. "Nautilus looked like the day it was applied."
All-in-one panelized sheathing systems, including Nautilus, Huber's Zip System, and Dow's SIS structural insulated sheathing, install like traditional wall sheathing and, when used with seam tape, provide a weather barrier and an alternative to housewrap. The sheathing systems offer builders new ways of meeting code and shielding their homes from moisture intrusion and air infiltration.
Dow's sheathing's 1/2-inch foam panels also provide an R-3 insulating value, while the 1-inch panels feature R-5.5, says Jim Gurnee, the manufacturer's North American new business development leader. Because the panels are used over a home's wood studs, they cover the "weak link" of the wood, which is a poor insulator (R-.5).
While each system has its pros and cons, Fava likes Nautilus for its simple installation and finished appearance during construction. Fava builds $1 million to $2 million homes, and clients for his upper-end dwellings require extra attention, he says. On Nautilus, the barrier holds tight and looks clean, he says, where housewrap might tear and need to be refastened or reinstalled.
Systematic selection
The cost of using such systems varies, however. On his first test home with Nautilus, for which he received the product at a discount, Fava estimates he saved about $1,750 on installation and $1,200 on housewrap. But he hasn't priced the sheathing on a routine home. Still, "I would use this even if it lost money because it looks so much better," he notes, adding that replacing housewrap after the storm would have added further costs.
Manufacturers say it is difficult to provide a standard price difference between systems because the costs vary based on construction type and installation, and because the systems are still relatively new. Georgia-Pacific says Nautilus panels cost $5 to $6 more than standard OSB sheathing, but says builders that have speced the system have experienced up to 15 percent material and labor savings over a housewrap system. Huber says panel costs typically vary from $7 to $9 per panel, and that many builders find significant cost savings in reduced installation time. Dow's Gurnee says the SIS system can cost more or less than a housewrap system. The Styrofoam SIS panels cost about $16 to $18, he says.
Rusty Rhodes, owner of Housewraps & More, based in Jacksonville, Fla., a turnkey installer of weatherization systems, says his teams have not seen any labor savings, and that using such a system costs him about 30 percent more than installing housewrap. Plus, he says, "I'm scared to death of that system." Whereas housewrap is shingled away from the home, panel seams sealed with tape are reverse-flashed, he says. "You're relying solely on that tape that they do not warranty. If that tape fails, the house is going to leak everywhere."
Brent Flotkoetter, associate product manager for Huber, points out that the company's Zip System tape has passed or exceeded all testing prescribed by ICC-ES Acceptance Criteria 148 for flexible flashing materials, and adds, "The tape's bond is three to five times greater than required by code, giving the user peace of mind that water will not find a leak path due to poor sealing or theoretical reverse flashing."
Wrapping it Up
While Rhodes is not convinced by the systems' performance, other pros may still be unfamiliar with the products. The systems all debuted less than two years ago and are still only a small portion of the marketplace. At the same time, the familiar standby housewrap is continuing to evolve to fill weatherproofing needs that panels cannot.
In fact, the housewrap market should grow 9 percent to 10 percent annually, predicts Raghu Tantry, a consulting analyst for research and consulting firm Frost and Sullivan. He attributes much of the growth to local building codes and swelling interest in green building and building science.
"There's an emerging trend toward sustainable building practices," says Bob Dahl, business director of Typar Construction Products. "Building housewraps can impact multiple areas of sustainability for residential homes." Housewrap mitigates moisture intrusion into the building envelope that can lead to mold and mildew and impact indoor air quality. It also provides air resistance, which can help to maintain the insulation's R-value.
Besides traditional products, manufacturers are offering more niche housewraps that work well with particular climates or building practices. Typar's StormWrap, for instance, meets the Miami-Dade County, Fla., missile impact-resistance test, allowing builders to use steel studs with exterior sheathing that can be insulated instead of cinder block or cast-in-place concrete. The product is significantly more than the price of Typar's traditional housewrap, Dahl says, but it can be cost-neutral to 10 percent less in a total installed wall system depending on how the home is designed. In southern Florida, for instance, a StormWrap-based wall system can be installed as a substitute for cinder block or cast-in-place concrete in the first 30 feet of construction, the company says.
DuPont Tyvek's climate-specific housewraps include StuccoWrap, popular in the Southwest for its ability to improve stucco curing and manage moisture behind the wall, and DrainWrap, used often in the rainy Pacific Northwest for its vertical grooves that channel bulk water away from the home.
With a metallized coating to create a "low-E" wall, ThermaWrap is popular in hot, sunny areas, and some builders are offering it as part of an energy upgrade package, says Laura Dwyer, residential marketing manager for DuPont Tyvek.
"Builders are asking for products to satisfy the way they build," she says. While the products don't come cheap--a roll of ThermaWrap costs about $175 to $180, compared with $135 to $150 for a regular housewrap--they may help builders differentiate their projects with improved energy efficiency and moisture performance. BP
Climate Concerns
The right housewrap depends on environment and building type.
While specialty housewraps offer unique performance characteristics for different climates, even basic housewraps differ significantly from product to product. "One size doesn't fit all," says installer Rusty Rhodes. "Different climates have a big influence on wall systems. Some [housewraps] shouldn't be used in some climates."
Most housewraps are designed to keep bulk water and bad weather away from the walls while remaining breathable to allow any water vapor that does make it inside to escape. Nonwoven, nonperforated products such as Typar, DuPont Tyvek, and Dow Weathermate Plus sport microporosity for permeance. These products, which make up 70 percent to 75 percent of the market, according to consultant Raghu Tantry, generally have higher air and water holdout characteristics. They also usually have lower tear strengths, however, and a median roll price of $125, Tantry says.
Woven or pin-perforated products such as Dow's Weathermate and Owens Corning's Pinkwrap are perforated with tiny pinholes that allow moisture vapor to pass through. The products generally have lower bulk water resistance, but higher tear strength and a median price of $95 per roll, according to Tantry. He predicts that perforated products' market share of 25 percent to 30 percent may grow slightly in coming years.
Permeance is another factor pros must consider. Measured in perms, a measure of water vapor movement through a material, housewraps range from high-perm products like Tyvek, at 58 perms, to low-perm products like Dow Weathermate, at 6.7. While experts make arguments for both types of products, use should vary by climate and building type. "There are so many variables within those categories ... that there is no easy way to generalize when one is more appropriate than the other," notes Dow's Jim Gurnee. "We consider the entire wall construction when advising builders on the right housewrap perm rating."
Raven
Raven. Fortress Pro weather-protective barrier uses a microporous, reinforced breathable membrane that withstands the demands of installation for long-term protection against water and air penetration, according to the maker. A grid of high-strength fiber reinforcement is bonded to a soft, nonwoven fabric for a lightweight but durable product with high staple and nail holding strength, the manufacturer adds. 800-635-3456. www.fortresspro.com.
National Shelter Products
National Shelter Products. Dryline building wraps are available in four grades. Dryline W is a high-strength, micro-perforated wrap engineered for value-oriented projects, the maker says. Dryline LP and HP are nonperforated wraps offering weather protection in both low-perm and high-perm versions. RainDrain is a multi-directional drainage wrap combining weather-resistance and functional drainage capabilities, the manufacturer adds. 800-552-7775. www.nationalshelter.com.
Georgia-Pacific
Georgia-Pacific. An OSB panel with a pre-applied weather-resistant barrier, Nautilus wall sheathing eliminates the need for separate building wrap installation, according to the manufacturer. The product offers an efficient installation process because it combines sheathing and building wrap installation into a single step, eliminating the need for a separate crew, the maker adds. The panels also can resist rain and moisture during the construction period, helping avoid moisture-related problems. 877-437-9759. www.gp.com/build.
Huber Engineered Woods
Huber Engineered Woods. Zip System wall sheathing uses 4-foot-by-8-foot panels with a built-in Stormex water-resistive barrier. The seams between the 7/16-inch panels are sealed with specially designed Zip System tape (pictured). The installation method creates an all-in-one structural wall system and water-resistive barrier, eliminating the need for housewrap, according to the maker. The built-in water-resistive barrier won't blow off or tear once the system is installed, the manufacturer adds. 800-933-9220. www.huberwood.com.
Dow Building Solutions
Dow Building Solutions. Styrofoam SIS structural insulated sheathing combines structural shear bracing, insulation, and a water-resistive protective barrier, allowing builders to install three layers of protection in one step, saving time and labor costs, according to the manufacturer. The boards are lightweight at less than 16 pounds per 4x8 panel, the maker says. The products are made with up to 80 percent post-consumer recycled content, the company adds. 866-583-2583. building.dow.com.
Fortifiber
Fortifiber. WeatherSmart housewrap offers a balance between breathability and water protection so that it can be used in any climate and behind most exterior claddings, the manufacturer says. The nonwoven, nonperforated wrap is resistant to contaminants known as surfactants that can reduce a housewrap's water resistance, according to the maker, and the product's breathable polymer technology provides a reliable, UV-stable air barrier. 800-773-4777. www.fortifiber.com.
DuPont
DuPont. A barrier that helps increase the thermal performance of a wall system by managing radiant heat flow, Tyvek ThermaWrap has a metallized surface and reflects heat away from the wall. The product also has a very high vapor permability at 36 perms, making it the only high-perm reflective membrane available, according to the manufacturer. 800-448-9835. www.dupont.com.
Typar
Typar. Designed to minimize penetration of windborne objects with higher impact resistance, StormWrap is a fiber-reinforced weather-resistant barrier that also adds water holdout for applications in extreme weather conditions, the maker says. A web of fibers acts as a kinetic energy dissipating net to catch and resist large projectile penetration while protecting against high wind pressure cycling, the manufacturer adds. 800-284-2780. www.typar.com.
Johns Manville
Johns Manville. Gorilla Wrap housewrap is a nonperforated, nonwoven polymeric material that helps keep the weather outside, reducing heating and cooling costs, the firm claims. The product is made of a translucent material that allows contractors to see studs, nails, and windows as they install, making it faster and easier than opaque housewrap, according to the maker. The housewrap's UV inhibitors and tear strength allow it to be exposed for six months. 800-654-3103. www.gorillawrap.com.
Owens Corning
Owens Corning. A woven polyolefin fabric engineered to be a weather-resistant barrier, Pinkwrap housewrap reduces air infiltration through exterior side wall construction while permitting trapped moisture to escape from the wall to the exterior, according to the maker. The product is translucent to simplify precise nail and staple location, and it resists tears in all directions so it stands up to windy conditions, the manufacturer adds. 800-438-7465. www.owenscorning.com.