The Evolution of Sheathing
In modern houses, the sheathing covering the studs and rafters serves a number of purposes. It’s structural, it acts as a nail base for attaching siding and trim, it’s an air barrier — a particularly good one when the seams are taped — and some newer sheathing also acts as a water-resistive barrier (WRB), keeping rain and snowmelt out of roofs and walls.
As useful as sheathing is, houses didn’t always have it. Traditional timber-framed homes gained lateral rigidity from diagonal bracing that was part of the frame. The siding was nailed directly to the framing, and served, along with the lath-and-plaster interior finish, as the air barrier. How did we get from no sheathing to highly engineered panels like Huber Engineered Woods offers in their ZIP System® family of building enclosure products?
Building Techniques Evolve
Timber framing is a slow, skill-intensive process that couldn’t keep up with western expansion in the United States. In the Midwest, a new style of building came into fashion: stud framing. Stud framing required smaller but more structural members and far less skill. Let-in bracing was largely replaced with diagonal wall sheathing made from sawn 1x boards nailed to the studs.
Modern Materials Take Over
By the mid-20th century, plywood entered the building world. Far faster to install than board sheathing, sheets of plywood flew onto houses. By the 1970s, the dwindling supplies of high-quality lumber began to have an impact. Costs rose. One answer was oriented strand board, or OSB — but every builder who’s installed commodity OSB in wet conditions has seen it swell from moisture.
Water-Resistive Barriers Matter More Today
Sometime late in the 19th century, builders began installing tar paper over board sheathing — the original WRB. In the 20th century, when insulation became the norm, wet houses couldn’t dry as easily, and WRB quality and installation became even more important. Builders and codes began to pay closer attention to the WRB in order to prevent houses from getting wet in the first place.
New Product Addresses Concerns
In the 1990s, Huber Engineered Woods brought a different type of OSB to the market that would solve the issue of swelling from moisture: AdvanTech® subflooring. Due to Huber’s advances in manufacturing and resin, AdvanTech stood up better to weather exposure without undue moisture absorption and swelling compared to other OSB panels on the market at the time. Finally in 2006, Huber brought ZIP System® sheathing and tape to the market. This wall and roof sheathing added a water-shedding outer layer to the OSB panels that already incorporated some of AdvanTech’s inherent water resistance.
Combined with Huber’s ZIP System™ flashing tape, the sheathing’s outer layer takes the place of housewrap in most cases where code requires one WRB layer. Builders no longer need to fuss with detailing and fastening flapping sheets of membrane on windy days. They can sheath and tape the walls as they go, and the frame immediately provides a layer of weather protection. The system is rated for 180 days of exposure1 to the weather, plenty of time for even the busiest roofer to get to the job. In most cases, using ZIP System® sheathing on the roof eliminates the need for a roofing underlayment such as tar paper.
ZIP System sheathing and tape key features and components include:
- High-performance engineered wood structural sheathing delivers Structural 1 shear strength and exterior durability.
- Built-in water-resistive barrier eliminates the hassles of housewrap or felt.
- Continuous, rigid air barrier decreases unwanted air leakage for greater energy efficiency.
- Specially designed acrylic seam sealing tape completes the system backed by a 180-day Exposure Guarantee and a 30-Year Limited Warranty2.
Today, Huber is still developing new products that continue to transform the building industry. As Tim Romans, Huber’s VP of R&D and Innovation, says, “We’re very active in our understanding of the need for resiliency. Our innovations spring from the need to make homes safe, strong, reliable and energy efficient. We strive to ensure ease of installation and the durability of the product over time.”
1 Limitations and restrictions apply. See HuberWood.com/Warranties.