538. High Humidity
28 Jan 2026 · 9 min
Derek Cole explains why your house feels humid in summer: up to 40% of your home's air comes from the crawl space. He recommends keeping indoor humidity between 40 and 60 percent, and shares how crawl-space encapsulation fixed his own floor rot problem.
Questions this episode answers
"Up to 40%" (citing BasementSystems/CleanSpace).
About 40–60% (host prefers mid-40s, ~42–46% in his home).
"538. High Humidity".
July 23, 2023.
Chapters
Hey, this is Derrick Cole. Welcome to the Derek Cole Podcast. And today I want to speak more about common problems this time of year and when you get into summer and the fall. Well, let's talk about common problems any time of year, really. And that is coming from your crawl space. We have a lot of calls in the summertime about humidity problems. My humidity seems high in the home. Is it too high? What can I do about it? Where should it be? What's going on? And I was reading we do a system here called Clean Space. It's from Basement Systems, and if you go to their website, it has a lot of great information. But they state studies have shown that up to 40% of the air you breathe at home is from the crawl space. So these humidity calls are getting, you know, you're checking out the unit. The unit looks fine. The duct systems being checked, the duct looks fine. Okay, so you have three factors for every home, right? You have the duct system, you have the unit, you have what we call the envelope, which will be the home itself. So if one of those three things are off, you're not going to be comfortable. If you have a home problem, there's insulation problem, the crawl space problem, the unit's not working right, there's holes in the ductwork, or the duct isn't sized right, you're not getting enough air. If1 those three are off, you're going to have a comfort challenge, a comfort problem at home. So same thing with high humidity. A common thing, especially in the summer, not so much in the winter, because in wintertime, well, remember, humidity is kind of like a blanket. So we don't get too many complaints in wintertime when it's cold, dry, outside of a humidity problem, because humidity is keeping you warm. It's something you want in the wintertime. It's not something you want in the summertime because we're in southeastern North Carolina. It's hot, it's humid, it's muggy. You want to get rid of humidity, get rid of the humidity and cool there down so you feel cooler. So you want to get the humidity out. So the humidity calls really come in in the summertime. Hey, my humidity is too hot. I was talking to William Skipper earlier. He said ideally, 40 to 60% humidity is. Is about where you're at. I know my house. I do have clean space because I have a crawl space problem that actually, you know, caused me to have to buy new floor because my floor literally rotted because the ground was so wet under it. So after I spent that money I got the clean space, the crawl space, and kept it in encapsulation. I'm not saying it right. Encapsulation, anyway, crawl space, ceiling. You know what I mean? So I have Ms. And the words come out slurred and messed up as well. So I think I'll blame it on that one right now. But anyway, my crawl space is sealed. So when you have a sealed crawl space, it is easier to achieve a bitter humidity level in the house, because as basement systems just said, up to 40% of the air in your home comes through the crawl space. So if it comes through the crawl space, this means that the moisture, the mold, dust, anything that's in that crawl space can come into your home and you start breathing it. So my midday usually stays between, you know, middle, mid-40s, low, low-40s to mid-40s, about 42 or 44, 46% is where I like it. You know, I think anytime you get, you know, 50% or above, 55% or above, you start feeling the humidity in the house again. It could be coming from the crawl space. So something to think about, something to look at. A lot of folks have plastic down the crawl space, which they believe is helping the crawl space, which is not helping their crawl space. I. I encourage you to go to Basementsystems.com and if you're interested, if you have free time, read up on crawl spaces, crawl space, moisture, crawl space treatment. It is, if you like the kind of stuff, it is quite fascinating to see all the research and all the facts about crawl spaces and things you're breathing. So check that out. But a common problem this time of year in the summertime is humidity. So what is that? What is causing the humidity problem? Well, we are in a humid climate, and now we know that studies say that up to 40% of the air we breathe is coming from the crawl space. So check the crawl space. I encourage you to, if you're able to go, grab a flashlight, grab some clothes, you don't mind getting dirty, go up under there, see what's going on with the crawl space. I think your eyes will be open to what's happening, what's there, or if you want us to crawl it and take, take photos, videos, we'll do that as well. If you, if you can't do it or don't want to do it, we would be glad to take a locator for you and let you know what needs to be done, what can be done. Sometimes you can only do what the house allows. Not sometimes, every time, you can only do with the house allows. So we always take that into consideration as well. So to land the plane here, wrap it up. One of the common things this time of year is high humidity. So I wanted to talk about that again, just to wrap it up. According to Basementsystems.com studies have said as much as 40% of the air in your home comes from the crawl space. So you're breathing that moisture, you breathing that dust, growth, whatever is in that crawl space, you're breathing it. So take that into consideration. That if the unit. Again, the three factors of every comfort situation is, number one, the unit, number two, the duck, and number three, the envelope or the house. So if one of those three are off, you're not going to be comfortable. So if you check the unit, it's good, and you check the duck and it's good, then it's got to be the home. Something's got to be going on that wasn't going on before. I've said this to our team before, you know, when they, when this, this system has been in for, you know, five, six, seven years. When did they start having this problem? Just now, the last few months. So what changed in the last few months to right now? What, what's changed? What, what has happened at the home? Did we cut some trees down? Did we add a room on? Do we take some insulation out by accident? What happened to change the dynamics? Did we change that windows? Did we leave it, Are we now leaving the screen door open? So take all those factors in consideration when you're looking at what's going on, what the problem is, because this is something we definitely want to check to see what that common problem is.
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