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Rim Joist Insulation Problems: 5 Things to Watch Out For
Amanda Ringler

By: Amanda Ringler on May 4th, 2017

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Rim Joist Insulation Problems: 5 Things to Watch Out For

open cell spray foam insulation  |  rim joist inslation  |  spray foam insulation  |  fiberglass insulation  |  insulation

Drafty basement with “that smell” getting you down?

Did you know little to no insulation in your rim joist could be responsible for several issues in your home, including that musty basement smell?

Other issues you may notice are cold floors, condensation in the basement, cold walls, as well as mold and mildew in the basement.

RetroFoam of Michigan has helped thousands of homeowners with their rim joist insulation problems over the past 15 years. We’ve seen it all, so we know how to make those rim joist headaches go away.

Here is a look at the top five rim joist insulation problems and how you can fix them.

Rim Joist Insulation Problems

Rim joist

  1. Moisture in the rim joist. Traditional insulation does nothing to prevent warm, humid interior air from getting into the rim joist. During the winter months – when the rim joist is cold – condensation can cause mold and wood rot.
    Using spray foam to insulate the rim joist will help to stop moisture from getting into the rim joist, according to Home Construction Improvement. This is because spray foam is an air impermeable insulation.

  2. Cold spots on walls. Cold air from outside can still get into your home by moving up through the rim joist. This will make the base of the walls around your home cold and will cause drafts. This is one of the top sources of heat loss and air infiltration in the home. This happens when there is no insulation or sagging fiberglass insulation in the rim joist.
    Solution: Updating the insulation in the rim joist is one solution, but gravity will take its toll on fiberglass, especially if it gets wet. Another option is open cell spray foam because it will stop the flow of air by creating an air barrier.

  3. Cold floors throughout the house. The cold air that is making its way into your home can lead to cold floors throughout your home. Those cold floors are going to have your furnace working overtime. The cause is again, little to no insulation in the rim joist.
    Solution: Updating or adding new insulation to the rim joist will help keep those floors warmer without constantly running the furnace. Not running the furnace as much will also save you money on your monthly energy bills.

  4. Drafty and cold basement area. Did you feel that chill run up your spine while you were getting something from your basement? Outside cold air that makes its way into your rim joist is guaranteed to make it into your basement. Cold basements are uncomfortable and not the easiest to keep warm if cold air is seeping in.
    Solution: To keep the cold air out of your basement, you will need an insulation material that will create an air barrier. Creating an air barrier in the rim joist will help with keeping the cold air out of your basement.

  5. Condensation in the rim joist and basement. Are you experiencing that basement smell and even mold or mildew issues? Condensation can lead to more moisture in the rim joist and basement. When this happens, you can smell the mildew in the air and could develop mold issues down there too. If you have duct work down there, the moisture from condensation could damage it as well. The musty mildew smell could also travel throughout the house via those ducts.
    Solution: Condensation happens when warm air is meeting the cold air in the rim joist. The condensation forms and creates moisture that will cling to fiberglass. The best solution is to use an insulation material that will create an air barrier. Spray foam will stop that air flow by creating an air barrier.

Answering Your Rim Joist Insulation Problems

The key to fixing your rim joist insulation problems is understanding how the different kinds of insulation materials work. Some homeowners have found that a better long-term solution to fix their problems has been to remove the old insulation and replace it with spray foam insulation.

If you are interested in learning more about the benefits of foam insulation, check out our learning center.

Home Insulation

About Amanda Ringler

Amanda previously has worked as a breaking news and crime reporter, TV news producer, and editor in Flint and Detroit. Throughout her career as a journalist, she has won several awards from the The Society of Professional Journalists - Detroit Chapter and the Michigan Press Association. As part of the RetroFoam of Michigan family, Amanda uses her experience as a journalist to write content that will help educate homeowners on the benefits of foam insulation. When Amanda isn’t writing, she’s spending time with her husband and rescued huskies. She also loves knitting, making art, cooking, and hosting dinner and a movie night for friends and family.