You live in an old house? Good! Then you have rotted wood and know the frustration and worries it can cause. When a tree is still alive, water is its best friend, but after we turn that tree into lumber, water is the last thing it needs.
There are lots of products on the market today to patch wood. I listed some of my absolute favorites in this post here:
The 7 Best Products to Patch Wood
But if you are in need of a serious rotted wood repair, then you need a serious product and a structural epoxy is the just what the old house doctor ordered.
Unlike wood filler, structural epoxies don’t just cover up cosmetic issues in wood. They can replace whole sections structural wood elements. So, rather than having to remove some damaged piece of the house, you can simply fill in the damaged portion and move on.
My favorite structural epoxy is Abatron LiquidWood & WoodEpox. This system uses a combination of wood consolidant (LiquidWood) used to strengthen and rejuvenate weak, rotted wood and a filler (WoodEpox) used to fill in missing sections of wood.
Here’s how to work with it:
Step #1 Remove the Damaged Wood
The first thing you need to do is assess the extent of the damage. You’ll need to dig out the severely damaged wood. I prefer to remove any wood that is mushy or weak enough to dig out with a screwdriver. LiquidWood can be used on extremely weak wood to strengthen it and bring it back to life so not all of the rotted wood needs to come out, but anything that is falling out on its own should be removed. Vacuum out the remaining debris and dust so you have a clean area to work with.
If the wood is still wet, it will need to dry out before you begin your repair. Cover it in plastic if you anticipate rain and make sure the sprinklers aren’t the cause of the rot while you’re at it.
Step #2 Prep & Protect
These are some serious compounds you are about to use and once they are in place it is very difficult to remove them (that’s the whole point isn’t it!) Anyway, you’ll want to mask off the work area with plastic and painter’s tape to prevent spills and drips.
Be sure to wear eye protection and nitrile or plastic gloves while handling any of these products. This stuff isn’t like shea butter for your hands. If it gets on your hands, think Chevy Chase in Christmas Vacation with the tree sap episode. Don’t touch without protection.
Have a container of acetone on hand which is the recommended cleaner and solvent for these products.
Step #3 Apply LiquidWood
Image Credit: Scott Sidler
Once everything is dry, it’s time to mix up your epoxy consolidant. LiquidWood is a two part mixture. Part A (resin) and Part B (hardener). These two should be mixed together in a disposable container like a dixie cup or similar in equal parts. (<—Very important!) Mix them thoroughly, or you will have lackluster results.
Let them sit aside for a few minutes to setup. After about 5 minutes, apply the mixture liberally with a disposable chip brush. Once mixed, LiquidWood and WoodEpox both have a working life of about 20-40 minutes depending on weather conditions (shorter working life on hot days, longer on cold days). Don’t get too busy and forget about your mixture!
Depending on the condition of the wood it may need more or less of the consolidant. Apply until the surface is soaked and let it soak in for about 10 minutes before moving to the next step.
Step #4 Apply WoodEpox
Image Credit: Scott Sidler
WoodEpox comes in two parts (a hardener and a filler) just like the LiquidWood. You’ll need equal parts of both and then blend them together until you have a uniform color. One is white and the other a tan color. If you see any streaks of color in your mixture, you need to keep mixing.
Once everything is well blended, it’s time to start pressing it into place. Press the mixture firmly into place to fill the missing areas. Press it deeply into the gap to make sure you fill any air holes and have a solid repair. The other important thing to remember is to leave enough epoxy proud of the surface so that when it is ready to sand, you have a smooth, well-blended repair. If you use too little, you won’t have a level surface to sand down to.
Step #5 Sand, Prime & Paint
The epoxy will begin hardening immediately and depending on the size of your repair, it will be ready to sand in anywhere from a few hours to a day. Warmer temperatures and bigger repairs cure faster, whereas small repairs in cool weather may take a full day. Below 50°F it may not harden at all so save it for a warmer day.
When it has hardened, sand the surface smooth and apply a coat of primer, then paint your preferred color. That’s it!
Abatron makes a really fantastic product and we keep gallons of the stuff in our shop to repair rotted windows and doors, siding, porch columns, really anything you can imagine. And the great thing about it is that the repairs are permanent. Abatron won’t fall out or fail like Bondo or even water putty. It creates a permanent bond with the wood. When your old house finally gives up the ghost the last piece standing will likely be your Abatron repair.
Here’s an idea of how serious a repair you can complete with LiquidWood & WoodEpox
Abatron is expensive, but in this case you truly do get what you pay for. If you’re not sure it’s right for you but still want to try some, I’d recommend getting the Abatron 24 oz. Wood Restoration Kit. It has small quantities of all four components and won’t break the bank.
If you have large areas to repair, then it is definitely cost effective to buy the larger 2 gallon WoodEpox & 2 gallon LiquidWood packages.
As always, if you buy through any of my Amazon affiliate links, you’ll get a great price and give The Craftsman Blog a small commission at no extra cost to you.
Happy patching and don’t be afraid of making that rotted wood repair. Let me know how it goes!
Founder & Editor-in-Chief
I love old houses, working with my hands, and teaching others the excitment of doing it yourself! Everything is teachable if you only give it the chance.
Hi Scot, read about Abatron and have used it! It works but can be tricky application. But what about gaps in siding boards? There’s movement and lots of weather exposure, so what’s best here? How about a caulk for wood? Like around windows? I know silicone is out but what’s OK?
I love this product. I’ve used it in repairing deck boards and rotted wood on my windows. I do have a question. I was repairing my window and ran out of the product. I need more to fill in, but want to know if I can put new wood epoxy on the old, to build up the structure.
Thank you
Is there a situation where this shouldn’t be used? We have a threshold and part of a door jam rotted. Would this product work or should we replace them? Thank you!
I have a camper that 6 in section floor to ceiling has water damage in drying it out was thinking about using this product to fill the gaps against the the outside fiberglass witch is in good shape any comments would be helpful
Tom, I am thinking about doing the same thing to a wall in our RV that has water damage. If you try this method, please let me know your results!
Can you screw into this and will the screw hold ?
We have to screw a partial rotted rail into partial rotted 6×6 post….
Yes, a screw will hold
I purchased the wood epoxy to fill cracks in a dozen 16′ t0 20′ 6″x6″ vertical deck/roof posts. The cracks run lengthwise and vary from small to 1/4″ wide and as much as 1″ deep primarily on the sunny facing side of the
posts. I have filled them in the past with Bondo and as you stated it has pushed out. It is fairly easy to remove what is left of the Bondo at this point and an angle grinder with a thin disk will clean the cracks. Can I [after cleaning] fill the cracks with wood epoxy [assuming no rot signs] directly or should I use prime coat first?
What if your 1908 house is covered with Bondo! The more lose sections we are “digging” off, but for the rest that just looks terrible, it’s just not smooth at all but is not cracking,
should we try sanding it smooth then applying your expoxy mix over it? ?
I have an old wood garage door. 1/4 of it is rotted – left half of 2 bottom panels. Would get a new one, except matching garage door is fine and don’t want to replace a perfectly good door so both match. Door has horizontal and vertical slats which are rotted, tongue and groove and hold flat, hard surfaced, non-rotted panels. Would you recommend this Abatron product for this repair? Husband wants me to use Bondo – not so sure that will work, especially after reading about it in your blog.
Abatron, NOT Bondo yes.
This product looks white. What can I use on unpainted wood floors
Big believer in long term tests but skeptical that your results are applicable nationwide. Specifically concerned about the additional affects of freeze – thaw cycles in areas with real Winters. Would be interesting to see this test repeated in a Northern state.
I have a question, what “should” the shelf life be for unopened one gallon containers of these products??
After getting a small bonus at work about two years ago I excitedly found a store in Buffalo that carried this product and purchased it!! (The product, NOT the store!!) I have an area of my sill that desperately needs repair and I figured this stuff just might do the trick!! Unfortunately I have never gotten to it and it looks like I will not get to it again this year. (Working too much)
The cans have not been opened, although were dented when I bought them, I probably should have asked for them to give me undamaged cans, but didn’t.
So again, by the time I get around to trying this product what might you think the chances are that it will still be as good or usable??
Dana Bennett
Forestville, NY
Here is my experience. I just completed a project using the liquid wood to repair rotted porch posts. I had 2 unopened gallons dating back to 2002. I took a chance, and used the product. The liquid was slightly amber in one container, but it mixed well. and set hard overnight. The product literature says that the shelf life is one year, but mine seemed to work well after 17! Who knows?
I am needing to repair architectural columns on an 1840 coastal home exposed top Maine winters. The capitals (tops) of the columns are Doric style and intricately carved. I need a product that can be roughly shaped and then carved back to the original detail.
Would this product or or would folks recommend another product that can be better carved?
I’d rather not use wood but might have to.
Thank you,
–Wm. Francis Brown
Camden, Maine
I repaired large chunks of rotted bases of columns that I first filled with Wood Epex and then shaped and sanded. They turned out great. My neighbors didn’t believe it and it would’ve take close examination to realize they weren’t the original wood.
FYI. The link to the product doesn’t go through.
Thanks for letting us know. We’ll fix it! -Alyssa at The Craftsman Blog
I have two approx 8 x 10 treated timber steps outside that have fairly extensive rot, though the majority of both steps, including the face, are still solid. I need to remove quite a bit of completely disintegrated rot before filling, and am guessing that I would need a gallon or two of whatever filler I end up using per step. This stuff looks like it’s meant for much smaller areas. Can anyone recommend another type of cement that could economically be mixed up in those quantities?
Do I still need to use the LiquidWood before the WoodEpox if I am building up a warped door panel that doesn’t have rot. I am assuming I only need to rough sand the wood panel and then use WoodEpox to eliminate the concave shape.
How thick can you place woodepox? Can you apply a second layer over first?
Thank you so much for this guide. It was very helpful
http://railwaywoodensleepers.com/
We have water damage on a part of the eave of our roof, from a leak existing before we bought the house. The wood is rotted and we can’t replace the whole board because it’s a flat roof that we just covered with silicon to prevent further leaking and extend the life of the roof (planning structural changes). Would you recommend the Abatron epoxy for that repair given that we stopped the leak?
Hello, I would have to agree with the engineering guys post above. As a termite inspector of over 20 years in California. The scope of said loc. Is to check all wooden areas of building in our inspection. Especially all structural wood members. In a case of any damaged wood members recommend for repairs, it is very seldom that it is recommended to remove any rot and repair with an approved apoxy. And only if treated with a fungicide prior to said repairs. And always recommended to open said areas (wall coverings-ect…) for further inspection. As damages may extend into I a areas. This is really the case with termites as well as dry rot, as termites travel from any piece of lumber to next piece when touching. And without removing said wood for repairs – one would never see the other damaged wood. That dose not include after they swarm, the can spread through out areas covered in drywall ECT… I would never recommend for any lic. contractor to fill any structural been, as for one too many variables that are just unseen, and second if and when said structural repair fails. Guess who pays for the necessary corrective repairs, also lic. Issues with the state. In California no house hose up for sale with out a termite inspection. As no bank will provide a loan on a shack of unknown structural integrity and workmanship.
can this product be used to repair rot in deck boards?
Indeed
I can’t figure how to start a new note, Scott, so I’m “piggybacking” here; I’m sorry!
I discovered rot in a porch post, where the railing joins it. Poked around with a screwdriver and it got bigger, plus I discovered the post is hollow; never guessed that till now, though it makes sense. I’ve carved away most of the rotten wood, so I’ve got a hole maybe 2″ by 4″; fortunately it’s in a flat, not rounded portion of the post. Can I use this product to repair that wood? And how do I deal with the hole behind it, so all the epoxy doesn’t flow down inside and disappear (I can’t afford enough to fill the whole pillar!)? I’m thinking maybe stick a large sponge in there and let it expand, or maybe spray in Great Stuff; or insert a square of fine mesh hardware cloth and pull it into place with a couple of wires I can then cut off once the epoxy dries. Any advice?
Thanks in advance,
Lowrie B.
Hi Lowrie, I realize I’m writing this two years later, so not sure if you’ll see this, but the issue you describe here is exactly what I’m facing right now. Just wondering how you ended up dealing with it.
Thanks!
I regularly use polyurethane foam (Handi-Foam) to fill non-structural gaps prior to whatever filler it is I’m using to finish the repair (joint compound, for example). You just have to make sure that you end up with enough of the original wood for the filler to adhere to. The amount of foam you use for backing any one repair is generally virtually free, though you do need to buy the whole can, so plan to fill some other gaps and cracks around your house when you use it. If you don’t use it all, it is entirely possible you can save the rest of the can for later if you clean/fill the applicator tube with carburetor cleaner. leave the tube right on the can and “trickle” the carb cleaner into it until all the foam’s dissolved, then pour that out and do it again.
Don’t buy the name-brand cleaner (handi foam, etc)… carb cleaner is half the price and the same effect.
Happy Patching!
Yes, it can be used for deck board repair, but economically it’s probably not worth it. Deck boards are relatively cheap. Abatron’s $40+ per quart. Do a cost benefit analysis. I find Abatron indispensable for things like repairing historic wood windows, which can’t be replaced at any cost. But unless there’s something very unusual about the deck boards, I’d just replace them.