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What Causes Condensation on Walls in a Home?

home insulation problems | existing wall insulation

What Causes Condensation on Walls in a Home? Blog Feature
Amanda Emery

By: Amanda Emery on June 16th, 2021

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The paint is starting to bubble on your exterior walls, leaving you scratching your head as to what the cause is.

Condensation inside of walls is the culprit, and the insulation inside is the accomplice. That condensation on walls in your home can lead to some serious issues, as well as some health concerns if mold is also present.

RetroFoam dealers across the country have helped homeowners dealing with walls dripping with condensation, but we’ll explain how they help a little later on. First, it’s important to discuss what is causing the moisture on your interior walls and then how you can prevent it.

Now, let’s get into the science of what causes condensation on walls.

What Causes Condensation on Interior Walls?

Condensation inside walls happens when there is a large temperature difference between the inside and the outside of the home.

If the insulation inside your exterior walls is lacking, or it still allows for air movement like fiberglass and cellulose do, then condensation will be able to form.

Condensation in the walls is most commonly seen in the winter months when it is frigid cold outside, and your furnace is making your home toasty warm. This is because it’s probably a balmy 75 degrees inside your house, while it’s closer to 20 degrees outside.

The stark temperature difference meets in the middle of the wall in the insulation and the condensation forms.

Think of a can in the summer that you just pulled out of your cooler. When the warmth meets the cold can it begins to sweat. The dewpoint, which is where the condensation will form, is always on the warm side of the can, or in this case, your home.

Condensation in the corner of a room will be even more prominent because that’s where the wall insulation will be lacking the most.

If the walls in your home are insulated with fiberglass, the contractor that installed it may have just pushed the material in the corners in hopes of making it fit. The issue with this is that fiberglass needs to be installed precisely in the cavity, or that space will be left with gaps. Another thing to consider is that fiberglass doesn’t create an air seal.

Cold air is going to get through your siding, then the sheathing, and lastly through the fiberglass. It’s going to transfer through to the drywall, where it connects with the interior warmth of your home. The dewpoint then develops right in the drywall.

In extreme cases, that condensation can actually freeze on the wall.

In the summer, the condensation obviously doesn’t freeze, but you’ll notice it because you will see mildew spores start to form near your floor and in the corners. If you boil a lot of water without turning on the range hood or take long, hot showers without turning on the bathroom fan, you’ll find that condensation problem to be even worse.

How to Prevent Condensation on Interior Walls

The best way to prevent condensation on interior walls is to stop the extreme outdoor temperatures from meeting the conditioned air in your home.

The best way to do this is by creating an air seal in your walls. Fiberglass and cellulose both still allow for air movement, but injection foam, like RetroFoam insulation, actually creates that air seal you’re looking for.

If you’d like to learn more about the benefits of RetroFoam insulation for your existing walls, check out the Learning Center on our website. You’ll find tons of resources to help you along on your journey, from the most frequently asked questions to how RetroFoam is installed.

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About Amanda Emery

Amanda previously has worked as a breaking news and crime reporter, TV news producer, and editor. As a journalist, she has won several awards from The Society of Professional Journalists - Detroit Chapter and the Michigan Press Association. Amanda uses her experience as a journalist to write content that will help educate homeowners on foam insulation benefits. When Amanda isn’t writing, she’s spending time with her husband Chris, daughter Lilith-Maeve, and rescued huskies Danger and Wendigo. She also loves knitting, making art, and cooking.