How does summer humidity affect a home’s basement?

- Tuesday, October 10, 2023

We all suffer from summer humidity. It’s terrible this time of year. In this episode, Adam explains how summer humidity affects a home’s basement.

Narrator: It’s time once again for the “Crack Man Podcast” hosted by A1 Foundation Crack Repair. I’m Darren Kincaid here with the Crack Daddy himself, Adam Tracy. Adam and The Crack Man Rich have over 30 years’ experience in the construction industry. Rich as over 25 years as the president and founder of . This podcast provides expert basement waterproofing, concrete repair, and preventative maintenance tips for homeowners and businesses. A1 Foundation’s valuable insight will help avert a disastrous flood within the basement, health problems associated with water infiltration, and protect your biggest investment….your home. The topic of today’s podcast: How does summer humidity affect a home's basement?

Narrator: So, Adam, we all suffer from summer humidity. It’s terrible this time of year. Based on your considerable experience, how does all the moisture in the air affect a home's basement?

Adam: This is a common question that we get this time of year. My basement is damp. I'm getting some dampness on the walls. It smells musty. What can I do? And for this conversation, we'll focus primarily on concrete foundations because that's the vast majority of the foundations that we see, and for most people, are trying to use as living space. This time of the year is very challenging because you have a basement that's below grade, several feet below grade, and as you get deeper into the soil to a certain point, it will stay colder. Obviously, colder than the air temperature, just like a cave. If you’ve ever gone into a cave on an excursion, on a vacation or something like that. They're always going to be a little bit colder.

When we're a little bit lower into the soil, that cold kind of radiates through the concrete walls. And the biggest issue is the air temperature and the air humidity that we have outside because the concrete's not going to change temperature dramatically over the course of a summer unless there's huge temperature swings, but for the most part, they stay relatively stable across the concrete.

What does change a lot is the actual air temperature and the air humidity. And the biggest thing that people will do, and it's the biggest mistake that I always see is they open up the windows. They say, “Ah, it's musty down here. Let me open up these windows.” And whether they're little hopper windows that are 10 inches tall or full height windows because it might be a walkout basement. That tends to be the first thing people do. And that's because, you know, if it was upstairs, that's what you would normally do. The problem is that because the basement is below grade and that warm air is coming in, you have a cold surface, warm moist air, and its immediate condensation.

You're actually aiding the damp musty basement smell by opening up windows, opening up doors. If garage doors are always open all the time and that connect into a basement area, those things will add into the humidity level of the basement. The area where you see the most moisture accumulating is typically the corner. So I'll get calls all the time from people saying, “I get this damp, dark spot in the corner of my foundation or several corners of the foundation. You know, I think I have a water issue.” And often, it's actually that three surfaces of concrete, the two sides and the bottom of the floor there, actually radiating colds into that area where warm air and moisture is coming in.

It's actually causing condensation on the walls. So, the fastest way to kind of rid yourself of this is to tighten things up. Obviously, houses that are built today and in the last 10 to 15 years have a much higher energy efficiency than ones built in the 60s or 70s. Just the way that these building codes are today. But with these foundations that are newer or even older, the first thing you need to do, close it up, make sure that it is a controlled environment as much as you're able to. Make sure that the windows are closed and are tightly sealed. Make sure that doors that go outside, they have, you know, weather stripping and all the tight closures to them, bulkhead doors, etcetera, making sure that everything is controlled in that environment. And once you've kind of crossed that hurdle, if it's still that moist damp basement smell, the next thing to do is to look at adding a dehumidifier in there. Dehumidifiers are basically air conditioners without a cooling mechanism.

If you ever walk into an air-conditioned fit space in the summer and it just feels better in there. It's not just because it's cool. It's because the humidity is lower, and that's a huge part of what makes people feel comfortable is the dew point and the relative humidity in the space. So, what we recommend is getting a nice commercial or a high-grade dehumidifier depending on the size of the space, that has an automatic discharging system.

You're not constantly moving the buckets around and keeping that humidity level at a reasonable 55-60% relative humidity. That's going to give you a lot of comfortable air moisture content in there that doesn't feel too dry like in the wintertime, but not too moist where you kind of get that wet basement smell. The third thing that you can do is look for any sort of flaws in the basement, any sort of foundation issues. That is a huge part that gets overlooked. Even though a crack may not leak, or whether it's a floor wall seam that leaks, or it has dampness to it, or a foundation floor crack, they may not get active water, but that organic breakdown of that smell is that's really prevalent in the summer and the moisture in the soils, that organic kind of decomposing of the minerals and organic matter will actually kind of give you that musty basement smell that comes up through foundation cracks in the floors and also through foundation cracks in the walls.

So simply sealing those, usually, professionally is better only because you have a better chance of kind of reducing that smell, will give you a huge advantage in not having that yucky kind of basement smell. So, the three big things are, one, make sure the room is as tight as you can get it and make sure the windows and doors are in good shape. Two, look at investing into a dehumidifier that is adequately sized for that space. And three, make sure that all of the foundation cracks are sealed around penetrations or any floor cracks. Even if they don't leak, they're all going to contribute to that basement smell on that basement moisture.

That will be giving you a nice living space, something that you could finish down the line or if it's already finished, giving a more pleasant atmosphere in the summer because that's typically when this happens. Wintertime, you're not going to notice it. Summertime, you'll notice it a lot. This would be the time to do it.

Narrator: Wow. Great information, Adam. Thanks for explaining how summer humidity can affect a home's basement and what you can do about it.

Narrator: If you have a basement water problem and think you need a professional, or, if you’d like more information on foundation crack repair and basement waterproofing topics, please visit or call Rich at (866) 929-3171. Or you can email Rich at Thanks for listening and keep that basement dry.

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A-1 Foundation Crack Repair, Inc. is a fully registered home improvement contractor. Contact us today to talk to a knowledgeable, master waterproofing professional.

Toll Free: 866-929-3171

Call Us Today at 866-929-3171

A-1 Foundation Crack Repair, Inc. is a fully registered home improvement contractor. Contact us today to talk to a knowledgeable, master waterproofing professional.