Is OSB (Oriented strand board) Waterproof?

OSB is a type of building material that is typically used in the construction industry because it’s relatively inexpensive. OSB became popular because it was easier to work with than plywood, and provided better protection against moisture and fire.

But is OSB waterproof?

OSB is made from strands of wood and adhesive which are thermally compressed together. The compressed wood strands create a water-resistant barrier that makes water penetration difficult.

However, while OSB is able to keep moisture out it’s certainly not entirely waterproof.

It’s possible for water to get inside of OSB if there is severe weather, flooding, or a roof leak.

Prolonged exposure to water will eventually cause the OSB to break down allowing water to get through it.

So it is certainly not fully waterproof.

How To Waterproof OSB

OSB can be waterproof by doing the following:

  1. Adding a layer of drywall to the outside of your OSB walls. This will not only provide protection against water but also protect against fire, pests and insects too.
  2. Add waterproofing treatment before installing siding or stucco overtop that can seal up any potential small holes which might otherwise cause leaks in OSB later down the road.

OSB is a very versatile material that is commonly used due to its low cost and speed of installation.

We highly recommend using a waterproofing treatment before installing siding or stucco overtop to avoid any possible issues down the road with water damage.

Also Read:

How To Waterproof Plywood For A Boat
Is MDF Waterproof?
Is Plywood Waterproof?

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