How To Waterproof And Weatherproof Plywood for Outdoor Use

Plywood is among the most commonly used materials for construction. Homes and commercial areas use it for outdoor and indoor constructions all the time.

When used for outdoor purposes, exposure to water, moisture and extreme weather conditions may affect them.

There are available methods to waterproof plywood for your different outdoor uses.

When taken good care of, it is very long-lasting and strong. It will serve you for a very long time, and it's cheaper than most woods.

When you weatherproof plywood, you will protect it from moisture and the sun and prevent rotting. 

Here is how to waterproof and weatherproof plywood for outdoor use...

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Use Water Seal To Waterproof Plywood

Water seal, as the name suggests, will help you protect the plywood from any water damages.

Clean the surface of the wood, and you can use sandpaper to smoothen it. It will also help you eliminate the loose particles or debris before you apply the water seal.

You will need a garden sprayer and water sealant.

After the surface is smooth, apply the sealant using the sprayer.

You should apply more than one layer of coat for the best results.

For you to maintain the water repellence for a long time, periodic maintenance is needed. After every two years, apply another coat of water sealant, or when there are any damages on the wood.

Polyurethane Varnish To Waterproof Plywood

Clean the wood with the same sanding process before applying polyurethane varnish.

You will need a brush to apply it, and it's best because it dries clear. It will give you a durable and desirable finish.

It is essential to apply a thin layer and let it dry, sand the plywood and apply the second layer.

Cover the surfaces with masking tape to only concentrate on the edges. If you apply it on the surface, the wood will not absorb any treatments in future.

The varnish treatment will protect it from weather and water conditions that may be damaging.

If you apply too many layers, the wood will look more like plastic. Make sure you stop once you get the results you want.

Water-Based Wood Stain For Waterproofing Plywood

You can also protect the outdoor plywood using the water-based wood stain. Use a sprayer for effortless workability and ensure you follow all the instructions given on the container.

Apply the stain all over the wood and allow it to dry before adding other layers.

Sand the wood in between coats for the best finish. Three or four layers of stain are ideal.

But more layers mean more protection from the direct sun it will be exposed to.

The water-based wood stain will add a little colour to your plywood, although it only comes in light colours.

Use a rag to clean the surface after spraying it to get rid of the dripping or excess stain.


The only downside of plywood is that they are mostly not waterproof.

Using these methods will weatherproof and waterproof it, leaving you with perfect construction material.

Humidity, the sun and many other conditions can damage the wood used for outdoor purposes.

To avoid severe damages and costly repairs, waterproofing is the way to go.

Protecting it will also reduce splitting. You should also select the plywood for outdoor uses correctly to enhance longevity.

The methods mentioned above are simple and easy.

You can do them yourself and protect the plywood in your home from any damages.