How to Fix Rotted Wood with Epoxy | This Old House

This Old House general contractor Tom Silva saves a rotting window with a two-part epoxy filler. (See below or a shopping list and tools.)

Tom showed Kevin how to repair a rotten windowsill and trim using a two-part "architectural" epoxy. The epoxy is designed to be flexible so that it will not separate from the wood as the wood expands and contracts with changes in humidity. Tom first grinded out the soft, decayed wood using a router. Next, he applied a bonding agent to ensure a good bond between the epoxy and the wood. Tom then traced the profile of the window trim onto a plastic putty knife and cut the knife to match the profile. Tom then dispensed the two-part epoxy using a special caulking gun onto the piece of plastic and mixed the two parts together. He then applied the epoxy to the windowsill and trim using his putty knives. Back in the loft, Tom recommended another application of epoxy for "touch up" and a light sanding before applying paint.

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Tools for How to Fix Rotted Wood with Epoxy:

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How to Fix Rotted Wood with Epoxy | This Old House

[adelaferreira]

Love Tom Silva, I have watched him for over 25 years and he always has something new for me to learn, thanks Tom !

[jeffthewhiff]

I like how Tom cut a special template from the plastic putty knife to have the correct profile of the wood. Very cool!

[Frankeex]

Cutting that knife for your perfect custom shape is such simple genius!

[jackriley]

I save the wood "dust" from sanding and use it when mixing epoxy. It stiffens the mix and makes it easier to sand. It works as well as expensive fillers.

[rjwalker]

I like the second way he mentioned. Take out just the rotted part and replace that with a small piece of wood. Saves time, effort and money.

[tompurtell]

Tom, after I learned about this product, I have kept a supply in my garage for the next project that pops up. Your window project in this video was a large undertaking and I have never taken on a project this large before. I have used this on window brick mold and other applications on the exterior of my house. Currently using it on my French door threshold. I have found in the cold weather it can take a lot longer to setup. I always get nervous thinking maybe I did not mix it correctly. Recently ART was sold out of the large double tube, which I love to use with the caulking gun. Due to Covid shortages they were having trouble getting stock for the large double tube. I was encouraged to order the smaller project size, which I do not like as much, I found when I went to reuse the smaller tube after a couple months, there was some hardening at the applicator tip area. I recently saw ART had the larger tubes in stock, so I bought one. It is great stuff.

[chrisgraham]

Automotive body filler (Bondo) available in "Classic" and stranded reinforced formulas for heavy build-up applications works very well at a fraction of the cost of the product that you are demonstrating. I've used it for rotted wood moldings and frames for 40 years, particularly useful for 100 year old Victorian scroll work moldings that are difficult to reproduce today. Applications on my own home that are 20 years old are holding up fine and undetectable today. Bondo is also a two part epoxy that can be drilled, sanded and shaped with common woodworking tools and no special applicator required.

[FranCording]

So wonderful to see an expert at work. Not enough worker like Tom Silva.

[ericbyers]

I still miss this old house and not to forget norm

[BearwoodBrown]

great tip about making a tool to match the profile I could have used it yesterday Thanks Tommy

[acerjuglans]

Show the whole process, beginning to end! I want to see the repair after it's painted.

[sxsboy]

It’s interesting to see that after grinding out the rot you can see the very tips of a finger jointed brick molding. When building my house some 30 years ago I installed 27 windows all of which came with brick molding made out of finger jointed scraps. Over the last 10 years I’ve had to repair or replace almost every one of those brick moldings AND all the rot started in the finger joints. Something I wish I had considered when making the purchase.

[catfishmudflap]

Tom is so clever. I love watching him work.

[Grendelbc]

Damn good show. I've been watching for many years. Thank you PBS.

[jeffthewhiff]

This is very cool! I have a couple of rotten window sills on my house and this technique should do the trick.

[jameshisself]

Great video! Good explanation of the contractor grade versions of this, but there are super easy homeowner ways to do this too. JB Weld 'Kwikwood' is a putty that you knead the parts together and once mixed you just press it into the void after clearing out the rot. You can easily knead it and shape it for about 20 minutes before hardening. After 1 hour it can be sanded and painted. Nowhere near as messy as this. The end result is surprisingly tough and blends very well with the wood.
Tbh, this rot is so extensive it would have been easier to rout out the remaining wood square-ish and cut a filler piece of wood to fill this large area.

[garykorzelius]

Thank you that was very good info. It will come in handy this spring, as I fix a. Few spots i noticed this winter.

[Olivia]

I learned from watching this video that we can tackle this ourselves! Thank you!

[ihatelogincrap]

I'd like to see how to fix windows made of field built wood frames attached to structural corner posts and go floor to ceiling where the bottom sill details is also baseboard trim detail where there's nothing really on the market to replace such big things and also preserve the look of the original mid century modern 1952 look.
But still I thank you for all the woodworking tips ! Your show helps demystify and builds confidence !

[GBV]

Thanks for sharing this great strategy