Wood is some incredible stuff. It literally grows from the ground and it’s durable, attractive, and easy to cut and shape—no wonder 90% of new houses are still framed at least partially using wood. Chances are the house you’re living in right now is absolutely filled with wood—from the beams and studs holding everything up, to the trim and other finishes.
And that can be a problem, because wood is vulnerable to rot. The air around us is packed with fungi spores, and those fungi would love to feast on the wood in your house. All they need is a broad range of ambient temperatures and some moisture to work with, and various species of fungus will begin feasting on your wood, compromising its structural integrity and transforming it from an attractive, strong building material into a crumbling mess.
Rotted wood is no longer reliable or attractive—but you might not need to tear it all out and replace it. It’s possible to repair rotted wood with just a few products and some time.
First, test for rot
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The first thing you need to do is learn how to identify wood rot in your house. Wood is often painted or hidden behind other materials, which is why rot usually gets to a pretty dramatic phase of destruction before we notice. To do a DIY rot inspection, grab a flashlight and any screwdriver and take a tour of the place. Things to look for include:
- Water stains. Do you see any evidence of water damage? Stains on walls, ceilings, or floors that indicate some kind of moisture or water intrusion will often be spots where rot has set into wood fixtures. Peeling or bubbling paint is also typically a good sign of a rot problem.
- Soft spots. Press the point of your screwdriver into any place you suspect there might be a problem. Even softwoods like pine should put up some stiff resistance. If your screwdriver sinks easily into the wood, it’s likely rotted.
- Discoloration. Areas where the wood has discolored—turning darker brown, white, or yellow—may indicate rot. These are perfect spots to break out the screwdriver and test for softness.
Once you’ve identified rotted areas, your next step is to determine whether a repair is feasible or if you’ll need to replace the wood entirely.
When not to repair
You can usually repair rotted wood with a fair degree of success, but it’s not always worth it—or smart.
Your first concern is cost. Wood is a relatively inexpensive material, and if you have a lot of rotted wood you may wind up paying a lot more to make a repair than you would just buying a few pieces of fresh material and replacing everything. Once you have an idea of how much wood needs work, price out the cost of repair materials versus the lumber—you might be surprised which approach comes out cheaper.
The second concern is whether the rotted wood is structural or not. Rot-repaired wood will never be as strong as healthy lumber, so if you have rotten joists or wall studs, it’s going to be best to just tear them out entirely and replace them once you’ve figured out how the moisture got to them in the first place. Stuff like wooden trim, casing, or molding, and window frames are ideal candidates for rot repair, as is anything with sentimental value—as long as it isn’t holding up your roof or something.
How to repair the rot
Once you’ve identified rotten wood and determined that it makes sense to repair it, it’s a pretty straightforward process:
- Remove rot and clean. Remove all of the compromised wood. If the wood is really far gone, it will be easy to tear out the rotted sections with a screwdriver or any other bladed tool. Be aggressive here; rot is like cancer, and you want to make sure you get good margins—keep tearing out wood until you hit hard, durable material that isn’t easy to scrape away. Then remove any dust or splinters left behind.
- Dry. Make sure the wood you’re repairing is dry—and that the source of the moisture has been addressed. It can take several days for moist wood to dry out sufficiently, so be patient. You can use a heater and/or a fan to try and accelerate this process.
- Harden. The key to repairing rotten wood is a high-quality wood hardener. There are many different kinds, but they all work similarly: You apply the hardener as you would a stain or paint, letting it soak deeply into the wood. After letting it harden for a few hours, the affected wood will be reinforced and restored to something close to its original strength and durability. You can apply several coats to ensure that your damaged wood is as strong as possible.
- Fill. Once you’re hardened your damaged area, fill in the void left behind with some wood filler. This stuff typically looks like cookie dough, and is very easy to pack into the space left behind by your rot damage, and it will bond tightly to the hardened wood. Once it has dried and set according to the instructions, you can sand it and shape it to match the rest of that area, then paint or stain it like wood.
Boom—instead of replacing something entirely, you’ve cut out the rot and repaired it. Don’t just stop there, though: The rot probably alerted you to a moisture problem in your home, and you need to fix the root cause.