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Ask the Builder: Wood epoxy works for rot

Ask the Builder: Wood epoxy works for rot

Column 1428

This wood beam rotted because it had no flashing on top.

My guess is you’ve seen wood rot before. If not, I'm guessing you live in the Atacama Desert, possibly the driest place on Earth. Wood rot is fueled by water, which is why it’s so important for you to keep all untreated wood in and around your home dry.

Keeping wood dry is more easily said than done, and you are almost certain to discover it somewhere at some point around your house. With luck, you will discover it before it’s so bad that the wood must be replaced. If so, there are wonderful products available that allow you to replace the rotted wood with a filler that you can paint or stain.

However, please note that repair products like this are not meant for structural repairs. If the rotting wood is part of a beam, or of a column that supports one end of a beam, you need to make the repair with a piece of wood that will have the strength to support the weight above it.

Four years ago, I traveled 3,000 miles to help a really good friend with quite a few items on his honey-do list. This friend invests his time every now and then to ensure my websites are running smoothly, and it was time for me to reciprocate. Fortunately, he lives in Southern California and the weather was perfect for my visit.

My friend lives in an association where the houses all have a distinct Southwestern look with some fake beams that protrude from under the roof overhangs. When installing the beams years ago, the original builder made a mistake. Even though Southern California doesn’t get much rain, rain does fall on these beams. One of these faux beams was showing signs of significant rot.

The rot could have been prevented if the builder or carpenter had formed a simple cap on top of the beam using a piece of aluminum flashing. The aluminum would have acted as a roof on top of the decorative wood beam, deflecting any rain to the ground instead of allowing it to sit on top of the flat beam. Installed correctly, the edges of this flashing would have been visible only to a trained eye. Most people would have thought nothing of it.

I share this with you because I want you to think of what went wrong at your home. What mistake did the builder make that caused your wood rot? You need to be able to remedy this after you make the repair so your repair work is not done in vain.

My friend’s faux beam had a large piece of wood missing from one side. There were also cracks and holes on top of the beam and on the end that had to be filled. I decided to use a waterproof epoxy product that can be sanded and painted once cured. This two-part epoxy is affordable and easy to work with.

There are exterior spackling compounds that can be used that require no mixing. I’ve tried one of the newest ones at my own home in the past two years, and it failed miserably.

I had some deep gouges in the handrail that is part of the steps leading down to my dock. I knew the spackling would fill the low spots, but I was concerned about the holding or adhesive quality of the spackling compound. Sure enough, after just 18 months, the spackling could be scraped off with your fingernail. This would have never happened had I used the epoxy I installed four years ago in California!

Once I removed all the soft, rotted wood from the sides and top of my friend’s beam, it was time to reinforce the wood. We had an assortment of galvanized coarse-threaded drywall screws at our disposal. I drove several long ones into the hole. These would act like steel rebar inside of concrete.

I then used some short screws in the large side hole. I drove these so the heads would be below the finished surface of the wood but well exposed within the hole. These would help hold the epoxy in place and act as anchors when completely surrounded by the epoxy. The bugle shape of the screw head would guarantee the epoxy would not fall from the hole.

If you don’t want to use screws as I did, then you need to excavate the wood so the bottom of the hole is larger than the top. Dentists employ this simple trick so fillings don’t pop out of your teeth. Road crews should do the same, but almost never do, to ensure asphalt doesn’t pop out of potholes.

The epoxy I used had plenty of work time. It was easy to force it into the holes and cracks. I used a variety of small and wide putty knives to get it as smooth as possible. The smoother you get it at the start, the less sanding you need to do to once it cures.

You can watch a video of me doing parts of this repair at Askthebuilder.com. You’ll be able to see the epoxy I used, how simple it is to mix and apply, and how to use the putty knives.

Type the following URL into your browser and don’t forget to put the GO in the URL:

GO.askthebuilder.com/repairwoodrot

(Subscribe to Tim’s’ free newsletter and listen to his new podcasts. Go to: AsktheBuilder.com.)

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