How to Fix Rotted Plywood

Fixing rotted plywood is not a difficult task as you may think it is. Below, we will explain how you can use a wood hardening product to fix and repair rotted plywood or wood paneling.

Rotted Plywood In Outside House Wall

In the back of my house, by my sunroom’s sliding door, I noticed the wood cedar bevel siding was soft and was starting to break apart. As I began to touch the wall, certain spots would start to cave in. I realized the wood cedar siding was rotting. I had some extra cedar panels so I began to repair the wall. As I removed the first few rotted cedar panels, I noticed that the walls plywood had severely rotten. I hadn’t planned on replacing the entire wall so I needed a solution to repair the plywood without completely replacing it. I learned you can use either a 2 part epoxy or a wood hardener to fix the issue. Below I will explain both solutions.

Rotted Plywood Repair with Minwax Wood Hardener

Rotted Plywood Repair with Wood Hardener

For my particular rotting plywood issue, I found that applying Minwax Wood Hardener to the rotting plywood would solve my issue. Minwax wood hardener penetrates deep into the wood and its special resin binds and reinforces the decayed wood fibers of the plywood. It then seals from further moisture penetration and hardens to a rock hard solid base for strength.

I allowed my plywood to dry as much as possible. I removed as much loose rotting debris from the plywood as possible without further damaging the plywood. I then applied the Minwax wood hardener to the plywood using a paint brush (disposable bristle brush). You can add several coats until a shiny surface appearance is obtained to further harden the desired area. Once applied, allow 2 to 4 hours of dry time. Once dried, the rot should be hard and now have strength.

My video did not show this but, for more severe rotted plywood situations, you can apply Minwax High Performance Wood Filler (or similar product) to the desired area after the wood hardener has dried. This will fill sections of the wood that have holes or have decayed away. Once the wood filler dries, you can sand it and even paint it however you desire.

Rotted Plywood Repair with 2 Part Epoxy

If you need to repair rotted wood with severe decay, deep gouges, or large sections missing, you will want to use a wood rot repair epoxy (2 part epoxy). If you’ve ever seen a non-glass bar table that has a clear top with bottle caps embedded inside, epoxy was used to create this finish. Flat horizontal surfaces are much easier to apply and fix rotted wood than wood that is vertical.

Wood epoxy examples that could be used to repair rotted wood.

For repairing rotted wood that can be laid horizontal, you can create a containment area around the wood and the area you need to repair. The containment can be created by using other wood pieces to control and contain the epoxy into the desired treated areas. Once you mix the 2 part epoxy together, you can start to pour the epoxy within your containment area. You then allow the epoxy to cure. Once cured, you can remove the containment pieces. The rotted plywood should now be fully hardened and prevent future rot from happening. You can see in the image above how you can use epoxy to fill voids in wood. I know this doesn’t show rotted wood repair but you can do the same thing to rotted wood.

For repairing rotted wood that must remain vertical, you may need to brush the epoxy to the treated areas or use a nipple bottle to apply to the treated areas. If you are able to create a containment area then do so. Since the epoxy will begin to drip due to gravity, you will need to monitor it and use your brush to smooth it out until it hardens enough to no longer move. Apply as many coats as you need to to achieve the desired hardness you want. More than likely, you will not be able to achieve a nice smooth, fully filled, surface by using epoxy alone on a vertical wood piece. Instead, once the wood hardens enough to alleviate the rot, you can then use a wood filler to complete filling any remaining voids in the wood.

Be sure to always follow the instructions of the epoxy manufacturer. Below are recommended 2 part epoxy products that can be used to repair rotted wood. Epoxy can come in different colors so if you want to add a cool looking effect to your repair, search for other color based epoxies.

We could have gone into much more detail but, since everyone’s situation is different, we tried to keep the information as open ended as possible. If you have any questions, please let us know in the comments. We will try to help the best we can. Thanks for reading!