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Business Advice5 min

The Importance Of Vapor Permeability In Building Envelopes

Since 1898, the American Society for Testing and Materials (now called ASTM International) has developed technical standards for a wide variety of building materials. They test for things like burn resistance. For weather-resistant barriers (WRBs), ASTM has developed rigorous tests for water resistance and water penetration, plus an air barrier assembly test. But an equally important test is ASTM E96, which measures water vapor permeability over a 24-hour period.

Even after exterior cladding goes up, walls can get wet. Small amounts of moisture in the wall turn to gas (water vapor) that needs to escape. If walls can’t dry out thoroughly, the home is susceptible to mold and rot. 

The term vapor permeability (sometimes called “breathability”) refers to a material’s ability to let water vapor pass through it. ASTM E96 measures this in units called “perms” – and today’s building codes require WRBs to provide 5 perms or higher.

The Difference Between House Wrap and WRB

Since the 1960s, many builders have relied on plastic house wraps to achieve superior vapor permeability. But house wraps are applied after traditional sheathing is installed and approved by code officials. Then a crew has to return to wrap and tape the whole house.

In contrast, a product like new LP WeatherLogic Air & Water Barrier requires fewer steps. The sheathing and weather-protective layer are combined in a single panel that can be installed just like regular sheathing. The panel seams are then securely taped with an advanced acrylic tape that features one of today’s highest quality adhesives. And because the vapor-permeable overlay is permanently integrated into the panel, it won’t tear or blow away.

One of the best ways to get a tight building envelope is to use a structural panel like LP WeatherLogic barrier where the sheathing and vapor-permeable layer are tightly bonded during the manufacturing process. It’s a breakthrough that involves fewer steps and less waiting than using house wrap.

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News & Stories6 min

LP® SmartSide® Trim & Siding: Part of a WUI-Compliant Solution

Many might assume engineered wood products wouldn’t be a good choice for wildfire-prone regions, but they can be part of a WUI-compliant solution. With LP® SmartSide® Trim & Siding, one of the most durable siding solutions available, you can provide homeowners with a strong exterior look for their home. And by combining it with LP® FlameBlock® Fire-Rated Sheathing, your clients can be assured their home has a durable exterior siding and walls that are compliant with requirements for ignition-resistant construction in WUI areas.

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Structural Solutions for Roofs in Wet Climates

Because moisture concerns are common across the United States, water-resistive roof underlayment is critical for any build. To help combat water intrusion, a roof underlayment provides a secondary barrier from moisture between the roof covering and the structure of the build.

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Building a Better World™: Letting Purpose Drive Our Business

Our purpose, Building a Better World™, had guided us in the years prior to 2020, but it was uniquely tested with this year’s challenges. As the comfort of home became increasingly important we sought to put our communities and customers first in new ways, serving them with the need for resiliency and safety in mind.

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Structural Solutions for Fire-Resistant Roof Sheathing

In fire-prone geographies, such as wildland-urban interface (WUI) areas, fire protection for roofs may be a critical part of a comprehensive approach to slowing the spread of fire and fire damage in homes. A fire classification roof system is required in WUI areas to protect your build and clients’ peace of mind—and with the right products, the installation process can be simple. Let’s take a look at fire-resistant roof sheathing and how it can help you approach building better in fire-prone areas.