News & Stories6 min

Water and Wood: Managing Moisture and Structural Materials

Water and Wood: Managing Moisture and Structural Materials 

Moisture is a big problem to solve on the jobsite with any wood product, even for products that tout moisture management. Before a structure is enclosed, it's highly likely that materials will undergo changes due to humidity shifts, rain and more.

Let’s examine the impact of water on wood building materials, how products from the LP Structural Solutions product portfolio can help you tackle moisture on the jobsite and how to avoid water damage to engineered wood. We turned to Jeff Yelle, Director of OSB/EWP Technology at LP, for insight on this important topic for building professionals.

Understanding What Can Cause Water Damage to Engineered Wood

Video courtesy of National Wood Flooring Association

Generally speaking, it takes lengthy and consistent moisture exposure for wood to rot and decay. The moisture content must reach around 19 % for wood rot to begin, and still, it is sustained exposure at this level that makes a difference. Even so, builders must work to prevent engineered wood water damage.

Water can be stored within a wood product in two ways: as free water (in the middle of the wood's cells) or as bound water within wood cell walls. Only bound water causes expansion, though. "Bound water chemically bonds itself within the cellular structure," Yelle explains. "When it does that, it pushes the fibers apart and makes them swell."

Wood's fiber saturation point, roughly 30 % for most species, is reached when bound water areas are completely full and free water begins to accumulate. "It's a really predictable process," Yelle says. "This allows us to be pretty accurate in how we predict what wood will do when we expose it to water."

3 Top Wood Products vs. Water

Video courtesy of National Wood Flooring Association

“Not all wood-based products will behave the same, and understanding these differences is important as you’re installing materials,” says Yelle.

Is traditional untreated wood water resistant?

Solid untreated wood adsorbs water at the highest rate of moisture content increase, taking only a few hours to reach saturation. However, if swelling occurs, it can mostly be reversed. Solid untreated wood can grow and shrink, returning essentially to its original size and shape, even with some level of irreversible swell.

Is plywood water resistant?

More water resistant, plywood takes in water at a moderate pace. However, since it has undergone physical and chemical changes during the manufacturing process, plywood is not as easily adaptable as it swells and dries. Plywood can be treated for mold and fungi resistance during the manufacturing process, but it tends to bow, cup and twist when wet.

Is OSB water resistant?

Engineered wood, also known as oriented strand board, takes on moisture at the slowest pace of the three materials. Manufacturers of engineered wood often include waxes and resins in the product to combat moisture absorption and prevent engineered wood water damage. These additives bolster the product's strength and add water resistance by penetrating into the wood fibers.

Innovative Solutions for Moisture Management

Engineered wood building products offer the moisture resistance you need to Defend Your Build from callbacks related to water intrusion, but they also bring strength, consistency and reliability to your projects.

For example, LP Legacy® Premium Sub-Flooring boasts panels packed with wood strands, waxes and resins using Gorilla Glue Technology® for exceptional resistance to moisture and edge swell. “These help to reduce the chance of any moisture-related damage,” says Yelle.

LP WeatherLogic® Air & Water Barrier eliminates the need for traditional house wrap with a water-resistive overlay bonded to the board, along with resins and waxes that combat and manage moisture. Approved for use on both walls and roofs, LP WeatherLogic panels are also Structural I rated for greater cross-panel strength and stiffness, helping you build a structurally sound and efficient home that lasts.

With LP’s moisture management technology, you can build better and with confidence that moisture on the jobsite has nothing on the defenses built into the products you’ve chosen.

Check out the LP Structural Solutions portfolio, designed and proven to Defend Your Build.

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