Business Advice5 min

Is OSB Waterproof?

The #1 problem on a jobsite? Water. Because when it rains, it pours.

When rain hits before a new house is fully closed in, it can be problematic not only for your construction schedule but also for your home’s sub-flooring and exterior sheathing.

At a time like that, there’s only one question: Is oriented strand board (OSB) waterproof?

Since not all OSBs are created equal, here’s what you need to know.

What is OSB and how is it made?

First, the basics: OSB is a type of engineered wood formed by adding adhesives and then compressing layers of wood strands in various orientations under heat and pressure. 

OSB is typically made with industrial grade adhesives that seal and bond the individual wood strands together. In addition to the adhesive, a water-resistant wax coats the wood strands for additional protection. Lastly, the edges of each OSB panel are sealed, adding more protection against water. This process makes the OSB board more water-resistant than other kinds of construction panels.

Do you need to waterproof OSB?

To answer the question “Is oriented strand board waterproof?” the answer is: not completely.

That’s because it’s virtually impossible to prevent some water absorption in a wood-based product, and moisture can be absorbed through cuts in the panel and the wood strands can swell.

All of this makes OSB a superior option for structural applications that require a product with some moisture resistance.

Is it okay for OSB to get rained on?

When using a premium water-resistant OSB product like LP Legacy® Premium Sub-Flooring panels, OSB can be rained on for some time with little to no worry about permanent damage.

LP took OSB and moisture management to a whole new level when it created LP Legacy Premium Sub-Flooring, the most moisture-resistant OSB that LP manufactures. It’s not only proven tough but also APA-verified for exceptional stiffness and strength. 

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

Is OSB suitable for outdoor use?

In the short-term, OSB can withstand some exposure to jobsite moisture. During construction, OSB can be left uncovered after installation for short periods of time. However, if you have uninstalled materials on the jobsite waiting for use, be sure to cover them per the manufacturer's instructions. Since OSB is often exposed to the elements, the OSB you choose must be highly moisture resistant, like LP Legacy 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 and wax to provide exceptional resistance to moisture and edge swell. The strands are aligned in a specific orientation, sent through a press to bond at the molecular level, and then cut to size.

Plus, the water-resistant resin used to manufacture LP Legacy Premium Sub-Flooring utilizes Gorilla Glue Technology® for unmatched moisture resistance and exceptional stiffness.

That’s not the only advantage. LP Legacy panels also feature RainChannel® notches on one four-foot end to improve drainage when rain suddenly interrupts your construction schedule. And it’s 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. 

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

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

The panels’ permeability allows moisture to dry, an innovation that provides reliable performance for years to come.

To create a Structural I OSB panel, LP’s innovative manufacturing process combines wood strands oriented in cross-directional layers with waxes and resins for greater cross-panel strength and stiffness.

An integrated, water-resistive overlay is added to finish LP WeatherLogic panels, completing an integrated wall sheathing panel that provides both air and water protection. Rated for both wall and roof applications, the system eliminates the need for secondary housewrap (or roof underlayment, in most cases) while increasing the structural integrity of the home.

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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