Business Advice5 min

Is OSB Waterproof?

The short answer is no, but the real question is: how does rain and water affect oriented strand board (OSB)? Let’s dig into the details of OSB’s construction. 

What Is OSB and How Is It Made?

OSB is a type of engineered wood formed with industrial grade adhesives that seal and bond the individual wood strands together. In addition to the adhesive, water-resistant wax coats the wood strands for more protection. The edges of each OSB panel are sealed, adding more protection against water. 

Can I Install OSB for Exterior Use?

There is a difference between “exterior use” and products designed for “use as exterior sheathing.” OSB is not suitable for unprotected exterior (outdoor) use, but it is well suited for use as exterior sheathing on walls and roofs. 

In both cases, the OSB will be protected from permanent exposure. The “Exposure 1” designation for OSB means it is designed to withstand short-term exposure to moisture during normal construction periods which means it can be left uncovered after installation for a short period of time without compromising structural integrity. However, if you have uninstalled materials on the jobsite waiting for use, be sure to store and cover them per the manufacturer’s instructions. 

Combatting Moisture on the Jobsite With Premium Materials

Since OSB is often exposed to the elements during construction, it’s critical to choose OSB that is moisture resistant. To help avoid sub-floor problems from pooling rainwater, choose a sheathing like LP Legacy® Premium Sub-Flooring panels. The key to the high moisture resistance of LP Legacy sub-flooring is how it’s made.

LP Legacy panels are packed with more strands, resin (with Gorilla Glue Technology®) and wax to provide exceptional resistance to moisture and edge swell. The strands are then aligned in a specific orientation and sent through a press to bond at the molecular level. The panels are then sanded, cut to size, profiled with a tongue & groove and LP’s RainChannel® notches, and edge sealed.

lp legacy with moisture resistance

That’s not the only advantage. It’s also easy to install, as this brief video demonstrates.

LP Legacy Premium Sub-Flooring comes with a unique Covered Until It’s Covered® no-sand warranty plus a lifetime limited warranty that lasts as long as the home.

As far as its water-resistant properties go, don’t take our word for it. Check out this one-minute video demonstration.

But LP Legacy panels aren’t the only water-resistant products LP has to offer.

LP WeatherLogic® Air & Water Barrier: A Better OSB For Both Walls and Roofs

With an integrated, water-resistive overlay, LP WeatherLogic® Air & Water Barrier is a Structural I OSB wall and roof sheathing panel that offers structural defense and protects against air and water infiltration when all panel joints are taped or sealed with LP WeatherLogic tape or sealant. 

The panel’s permeability allows moisture to dry, an innovation that provides reliable performance for years to come. Rated for both wall and roof applications, the system eliminates the need for housewrap or roof underlayment, in most cases.

lp weatherlogic panels after rain

To create an even stronger system, you can build with accessories for several LP Structural Solutions products. 

For flooring, it is important to use a sub-floor adhesive such as LP Legacy® Sub-Floor Adhesive, which can be applied with LP TopNotch 350 and LP Legacy sub-flooring to help protect against squeaks. Pair LP WeatherLogic panels with LP WeatherLogic Seam & Flashing Tape or Sealant to create a tight building envelope that seals out air and moisture. 

LP Structural Solutions accessories are easier than ever to get in your hands. Shop them on Amazon here.

lp structural solutions accessory products

As The Song Goes, You Can’t Stop The Rain

You can’t stop the rain, but you can certainly minimize water damage to your sub-flooring and sheathing by choosing products like LP Legacy Premium Sub-Flooring and LP WeatherLogic Air & Water Barrier. 

For more information about LP Legacy Premium Sub-Flooring, visit or click here.

To learn more about LP WeatherLogic Air & Water Barrier, visit or click here.

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