Wow, a page dedicated to wood rot! I bet you’ll find this as exciting as me!
Most of us have gone through life just accepting wood rot, termite and other damage. It’s just part of owning a house, right?
Hopefully, you’ll see that most wood rot is totally avoidable. Yep, you got that right. You don’t have to put up with rot.
Stupid, avoidable rot
If you look at almost every place you find rot, you can trace the rot back to water. Wood installed in dirt. Wood in contract with contract near the ground. Unprotected wood forming ledges where rain sits and soaks in. Flashing installed improperly. Vapor barriers in the wrong place. Humid basements and crawlspaces. All these things can lead to rot and all are avoidable.
The key to avoiding rot is to respect moisture and understand basic physics and let things dry out. And by basic, I mean the type of physics you learn in grade school. You know, water runs down hill. Water can go uphill if it’s sucked into a sponge. Water evaporates under the right conditions but it sticks around in a terrarium. That’s about it. Understand these things and you’re better off than most builders. No joke.
Look at the picture above. What happened?
First, check out the trim board. I’m sure it was beautiful when the builder nailed it on and subsequently painted the wall, but if I had seen this being installed, I would have told the builder “that is guaranteed to rot out, and sooner than later.” If they didn’t throw me off the work site or hit me with a 2×4 for being a wise guy, they might have learned why.
First, notice that the rotten wood behind the trim wasn’t painted. Most wood acts like a sponge, especially when the end grain is exposed. The builder painted the wood after they nailed it on. That’s usually fatal. Most types of unprotected wood, installed near the ground, is guaranteed to rot. It’s not a tree – don’t plant it in the ground.
Second, remember your grade school physics. Water runs down hill. It will also seep into narrow spaces where it will sit until it is totally absorbed or it can evaporate. When it rained, that trim piece allowed water to seep between it an the unprotected wood of the wall. Worse, once the water got in there, surface tension and other forces would hold it in that crack, where it would slowly soak into the wood. Then it would rain again, and the water would soak in more. That wood never had a chance!
Third, as noted above, the wood is installed basically on the ground. What’s the ground? It’s a big sponge. It’s wet. It releases water continuously. Any time you have wood too near the ground, if it’s not protected wood, it will rot. Read that again. It will rot. I guarantee it. Wood should be kept at least 6″ from the ground. Probably more. With landscaping. Mulch, etc., that 6″ will shrink over time and before you know it, that wood will be sitting in a puddle. And then the termites or other critters will come. They love wet wood. And then you’re doomed.
The Rotten Hall of Shame
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A bad stucco job destroys a home.
Just how bad can it be? One of my first jobs involved a beautiful stucco home with persistent moisture problems. At first, I was called in because the interior finish was peeling off the walls. I found the source of that moisture, but warning bells were blaring in my head because I observed improper flashing techniques and the house had a history of moisture problems.
I took the analysis to the next level and tested the moisture inside the walls and found high moisture in the walls all around the house! This was getting very uncomfortable. The builder and I discussed the problem and my conclusion was – the entire house was compromised and if not dealt with, it would be destroyed by moisture related issues.
I have to admit, I was afraid that the builder would start tearing off all the stucco and find no problems, but those fears were not realized. Instead, all over, he found scenes like shown in the photo above. Major structural members of the house were rotting away! This house literally could have self-destructed.
Ted's Energy Tips 
Thanks for the info, Ted. I’ll do my best making sure he does the job properly and do what I can to clean things up properly. Here’s hoping we don’t ever have to replace any other windows. I will be sealing all of the other windows as well to prevent problems around the rest of the house. We have no intention of ever moving, so we want this house to be in the best shape possible.
Hi Ted,
Your brother Stephen from Santa Fe here to ask you about this project and what became of it. With this much rotten wood, was it resealed/replaced/ or torn down? Was the house tested or treated for mold? I ask because we had some unusually hard driving SE rains that forced water in our master bedroom. After tearing the sheetrock out, we found the bottom of the window frame and some wet wood that had started rotting turned black. I was told the windows were the source of the problem, so they were ordered and just installed. The rotten wood has been cut out, the 8 Pella windows were just replaced, and now I want to make sure we have things as clean as possible to prevent future mold issues. So my long winded question here is, have you had to deal with much mold, and how have you dealt with it. Moisture usually isn’t much of a problem out here, 40% humidity is considered high around here. (it is currently raining here and it is 41% RH)
Thanks for your time,
Stephen
Hey Stephen!
In the case of the stucco homes with rot, I’ve unfortunately found, as they say, “where there’s smoke, there’s fire.” That is, finding a little rot is often indicative of improper construction and a full tear-off/re-do is in order. For example, check out this project currently in process.
On the mold issue, keep in mind that once the moisture problem is fixed, the mold will not grow more since it needs water to grow. Often people panic when they see mold but a bit of mold inside the walls or on building materials usually isn’t a big deal. Some people have extreme allergies, so there are certainly cases where you have to be more careful, but we breathe mold spores all the time with few ill effects.
Getting back to your question in specifics – I hope they redid the flashing on the windows! I have rarely found that the windows themself are defective, it’s almost always the case that it’s the installation of the flashing around the window that causes problems. Take a look at some of the photos shown here. A lot of installers think that if they just put tape around the window flange it will seal everything. But what happens if water gets behind the tape? How is the water going to get out? As shown in those photos, water got in around the top and was never directed back out so it kept streaming down the inside of the sheathing leading to catastrophic wall rot.
I always recommend that people download and print out the manufacturer’s installation guidelines and give a copy to the installer and insist that they follow the guidelines to the letter. For example, for your Pella windows, here is the installation guide. In particular, note how the house wrap goes UNDER the window flange on the sides and bottom of the window but OVER the flange at the top (Step 4). This guides the water properly. Most installers, unfortunately, just wrap the house wrap around the opening of the window then nail the window over that. Of course, that means that water running down the wrap will go BEHIND the flange at the top. From there, you’re doomed 😦
In Santa Fe, you’re lucky with the dry air – that will suck out moisture pretty quick, though, as you saw, even then you can get wood rot if the water gets trapped inside the wall. You really shouldn’t have anything to worry about if they did your installation and repairs properly. But if the didn’t, you’ll end up with more rot in another few years no matter how careful you are cleaning out mold.