IN DEPTH: Housewrap and Insulation
As the green building movement has gained momentum over the past decade and energy efficiency has come to the forefront— due to homeowner demand, contractor differentiation, and increasingly stringent building codes—so has interest in building science. More designers and builders are paying attention to constructing envelopes that better manage air and water. And central to those efforts are housewrap and insulation products.
“Builders understand now better than 10 to 15 years ago that keeping the structure dry is an easy, cost-efficient way to protect their reputation,” says Scott Tennison, global director of building materials for Kimberly-Clark.
Building codes are having a significant and positive impact on insulation and air sealing in residential construction, says Lamar Anderson, director of marketing for Foamular at Owens Corning. Also, builders are asking questions about how they can offer the best quality products while reducing overall costs.
“As we continue to build homes tighter and tighter, the room for error is getting smaller and smaller, and that’s what’s driving these changes,” says Chris Yount, president and COO of Fortifiber.
Before, Yount notes, air was passing through the cavity so much that it dried out. But as we’ve decreased energy transfer through the wall, the margin for error has shrunk. “We have to really be on top of these details to get them exactly right. If they’re just a little wrong, the failure can be catastrophic.”
Increasingly, those details include a weather resistive barrier (WRB) and compatible seam tapes and air sealing.
“The three fundamental principles at the heart of building science—air, heat, and moisture flow—have played a key role in the product choices that are available today, and our building codes are also embedded around these principles as well,” says Ted Winslow, product manager for building science, systems, and technical marketing at CertainTeed. “As we started tightening up homes, we learned of moisture challenges because they couldn’t dry out as easily. Products like CertainTeed MemBrain, a continuous air barrier and smart vapor retarder, can solve these challenges by providing active moisture management within the wall.”
|CertainTeed has introduced an Insulation Selector Tool to help builders and contractors assist homeowners with understanding and selecting different insulation systems. This tool uses climate data, budget, and other needs to recommend a personalized selection of insulation solutions. A customized version is available, providing branding and recommending only options within a builder’s inventory.|
“Housewrap continues to be one of the best investments a builder can make for themselves and their home buyers,” says Jorge Martinez, senior director of product marketing for Typar. “The Department of Energy has demonstrated that the use of a housewrap can provide 25% to 40% savings annually on energy costs in a typical home. Given the increasing costs of energy and the desire by consumers to select products that help them conserve energy, housewrap certainly fits the bill.”
Understanding how different housewraps work, and what’s appropriate for your climate zone, is key to ensuring WRBs work as designed. “[People] think from a logical standpoint if you keep water out of the home it’s naturally going to keep air out, but from a building science standpoint that isn’t always the case,” says Tennison. “It’s important to choose a quality low-perm housewrap that can not only keep water from coming in, but also provides the barrier to air, and still allows for water vapor to escape the structure. The housewrap your customers choose should be able to do all three.”
In fact, there are more options than ever for envelope products that serve multiple roles or better manage air and moisture. “On the functionality side of things, the big trends that we’ve been seeing for the past few years now are products and systems that are designed to service not just one need, but many,” Winslow says, calling out products such as those that combine housewrap and sheathing and those that provide thermal performance benefits as well as moisture management and air tightness. “The features and benefits of these systems all vary as well depending on the needs of the audience that they are serving.”
|Polyguard’s PolyWall Blue Barrier Flash ’N Wrap 2400 liquid-applied window and door flashing creates a continuous, durable, seamless membrane. The single-step product applies with a roller or brush and dries quickly. It is permeable, allowing substrates to breathe. The product also can be used as a permeable air barrier wall coating for thin-mil building envelope protection applications, the company says.|
Among those options are drainable housewraps, which feature dimples, gaps, or channels to help water drain down and away from the assembly, providing an alternative to adding a rainscreen (or nothing at all).
Kimberly Clark’s BLOCK-IT* housewrap, for example, channels more than 98% of water away from the wall assembly. “We believe drainable housewraps offer the best performance for keeping the structure as dry as possible, and we utilize the best science on the market to continue to improve weatherization,” says Tennison.
Fortifiber offers WeatherSmart Drainable, a dimpled version of its traditional housewrap. “There’s been a wider understanding in the industry that increased drainage efficiency helps improve durability of the wall by getting incidental moisture out more efficiently,” says Yount. “So there’s been an increased introduction of drainable housewraps.”
|Huber Engineered Woods’ ZIP System R-sheathing includes the system’s integrated water-resistive barrier, which eliminates the need for housewrap, along with built-in polyisocyanurate continuous foam insulation. It comes in a variety of thicknesses; the R-9 version helps builders meet prescriptive continuous insulation requirements in the 2015 energy code, the company says.|
“Several states including Oregon now require the installation of a drainage system as part of their building code. We believe more states will begin to institute this mandate as well,” says Martinez, whose Typar HouseWrap DW combines a water-resistant barrier and drainage system into one product. “As drainage wraps continue to evolve, [dealers] can expect to see a substantial increase in high-end construction specifying drainable wall designs either by the architect or builder, both of whom have become very sensitive to moisture management complaints due to lack of drainage and drying.”
Another trend is combining a weather- resistive barrier into the sheathing, as seen in Huber Engineered Woods’ ZIP System and Georgia-Pacific’s new ForceField, both of which eliminate a step in the installation process.
|Typar HouseWrap DW features multi-directional spacers that create a drainage space between the sheathing and cladding. According to the company, the product provides a 96% drainage efficiency and removes 100 times more bulk water from a wall when compared to standard housewraps.|
“Builders are having to do more with less, so any product that helps them get in and out more quickly without sacrificing performance is helpful to them and a win for them,” says Jeff Key, marketing manager at Georgia- Pacific. ForceField panels install like regular OSB or plywood, then seal with ForceField seam tape. Key says the company estimates that builders and contractors can save up to 35% to 40% in time, contributing to lower burdens and installed cost at a time when the industry is facing labor shortages.
Huber’s line now includes a range of accessories, including its original ZIP System Tape, along with a flexible tape and a fluid-applied flashing. A new insulated version, ZIP System R-Sheathing, combines the benefits of ZIP System with pre-applied exterior insulation.
Dan Thomas, business development manager for Polyguard Products, says fluid-applied flashings and air and water resistant barriers are becoming more common in residential applications. “These have been used in the commercial segment for the past decade,” he notes. “Those technologies are rapidly moving into the residential construction space.”
|BLOCK-IT* housewrap from Kimberly- Clark is a drainage wrap that channels water away from the structure while providing a breathable barrier. The housewrap provides excellent breathability, channels more than 98% of water away from the wall assembly, and is 35% stronger than the leading housewrap, the company says. BLOCK-IT* Seam Tape and Flashing Tape help complete the envelope.|
“The number one litigated item in new residential construction is water intrusion and resultant damage that is created. 90% of that water intrusion occurs at either transitions of dissimilar materials [windows/doors] or penetrations in the assembly [electrical outlet/ hose spigots],” Thomas explains. “While traditional WRBs and flashings are still widely used in the marketplace, they must be installed correctly in order to perform as designed. Builders are looking for a simpler way to waterproof their walls, transitions, and penetrations with products that can withstand the rigors of the jobsite, long exposure to the elements, and ultimately over the life span of the structure. Those criteria are the basis of the chemistry backbone—STPe—of our Blue Barrier product group.”