Recovery in home building and revamped energy codes are combining to drive the adoption of housewrap products that not only improve drainage in the wall cavity but also help form envelopes that better manage airflow.
“It’s actually back to the future,” says David Martin, manager of new business development with IPG. “Housewraps were originally air barriers. Then water became the focus over the last 10 or 12 years. Now we’re getting back to basics with the focus on air.”
To that end, the latest round of product updates features hybrids that combine the decades-old moisture-control spec with a looming air-barrier mandate; the 2012 International Energy Conservation Code (IECC) includes an inspection checklist that focuses on how the product is sealed.
Ten years ago, fewer than half a dozen manufacturers made products that fit this bill, says Laverne Dalgleish, executive director of the Air Barrier Association of America. Now, it’s status quo.
Solving both air and moisture issues is contributing to what experts call a systems approach in home construction, in which a wall cavity is only as code-compliant as its least-efficient member. “The codes are driving additional R-values and thermal insulation, whether it’s in the cavity or the exterior,” says Alan Hubbell, DuPont’s marketing manager for building innovations. “It’s all for naught if you don’t manage air through the wall.”
Ken Jacobson, managing partner at market research firm Principia, says it may be years before a sizeable number of states adopt parts or all of the latest IECC. By the time they do, he says, housewrap manufacturers will be primed to respond.
Steve Hardy agrees—in part. “Codes always point the way,” says Hardy, a market manager for Hayward Lumber in Monterrey, Calif., which sells Tyvek and Siga housewrap. “But concerns about litigation and client dissatisfaction have been major influencers for our builders.”
So far, wrap makers have been able to meld a code-driven approach with builders’ longtime concerns over liability and performance. Roughly 1.9 billion square feet of material worth $530 million was used in 2011.
Cosella-Dorken recently launched its Delta-Vent SA vapor permeable water resistant air barrier, featuring a 2-inch-thick, self-adhesive edge lap to forgo the need for fasteners, which can cause holes. The edge connects to the top of the wrap’s front side and is locked down with a release liner. The product works on several substrates, including concrete, masonry, OSB, plywood, and exterior-grade drywall.
IPG entered the housewrap market in 2009 with its NovaWrap product family. Its value-added Aspire, uses micropores to transmit vapor in and out of the wall cavity while meeting the 2012 IECC requirements for a continuous exterior air barrier.
The CertaWrap Weather Resistant Barrier from CertainTeed is sold alongside the company’s suite of accessories, including flashing and seam tape.
Microperforated products such as Dow’s Weathermate system and OwensCorning’s TruWrap and PinkWrap use woven sheets of fabric with mechanically added holes to give moisture an easy path out of the wall. The Weathermate system was designed for use with non-insulating sheathing, meeting International Building Code and International Residential Code requirements for weather-resistive barriers. The system also includes seam tape, a sill pan, a foam sealant, and flashings. TruWrap is translucent and can be stapled. Like PinkWrap, it’s touted as an air and moisture barrier that also lets water vapor escape.
Manufacturers are stepping up their game by producing goods linked to geography—particularly climates that get a lot of rain.
Benjamin Obdyke’s drainable HydroGap boasts a tri-laminate substrate sandwiching a moisture barrier between non-woven layers. Zigzag spacers on the housewrap’s surface create a 1-millimeter gap between the sheathing and cladding to improve drainage speed and let the housewrap be installed in any direction.
Pactiv’s GreenGuard brand earlier this year revamped its 8-year-old RainDrop 3D, a translucent, non-perforated air and moisture barrier that features drainage channels that the company says don’t crimp or flatten. The product can be installed under a range of claddings in residential and commercial applications.
DuPont’s Drainwrap’s vertical grooves channel water behind claddings such as fiber cement siding, wood, and foam board. The company’s StuccoWrap is also designed to meet drainage needs, and its cladding-specific application is something that experts expect the market to like. ThermaWrap features a low-E surface to reflect heat away from the wall in warmer climates and keep heat from passing through the wall in colder areas. Still, Hubbell says his company’s nonwoven, entry-level HomeWrap sells the most.
In marine climates that face wind-driven rain and adverse weather conditions all year, housewrap alone isn’t enough. IPG’s Martin recommends a 3/8-inch gap between the housewrap and the exterior cladding, plus a rainscreen, to keep water from becoming trapped in the wall cavity in those climates.
Yet for all the innovation in the housewrap market, architects and builders aren’t likely to drop the old standby, felt paper. Peter Pfeiffer, an Austin, Texas-based architect who specializes in sustainability, says he uses a 1-foot strip of rubber and 30-pound felt along the gap between the home’s foundation and its sheathing. “It’s one of those classic old products that work so well,” he says.
Which Comes First?
Manufacturers’ spending on research and development (Fiberweb recently dished out $20 million for a new research facility) is hinting at the same thing: A rebound in housing starts that will correlate with the new mandates aimed at products’ ability to contribute to an energy-efficient envelope (if and when the codes are picked up). Which is to say that if builders have yet to begin building with newer technology, it’s only a matter of time before they will. Where builders previously bought on brand allegiance, experts say the codes are likely to force them to evaluate products’ specs and make their choices based on the products’ use of efficient systems.
Tools that combine building-science and visualization technology may prove to be an asset for builders and dealers as the industry grapples with changing codes and building practices. The new CodeSense Durable Wall Builder from DuPont applies a concept other manufacturers have used with siding, windows, and doors, this time referencing codes, cladding type, and climate zones.
“It uses our building science and it quickly provides guidance on how to build durable wall systems that manage air and water,” Hubbell says. “It gives the user code requirements for their particular situation and detailed how-to instructions to build against those requirements.”
Knowing how to install housewrap products to maximize energy efficiency is key when quantifying their contribution to the wall cavity’s performance, experts say.
“It’s complicated,” Hubbell says. “It drives us to make sure we have good education, good training, and that our [reps] understand good fundamental building science.”