Do basement walls need to breathe?

Nowadays, houses are sealed up tight as a drum. It’s great for energy efficiency and your heating bill. But it’s bad for any moisture hiding in your home that can’t find its way out. That is why your walls need to breathe.

Should you put a vapor barrier on basement walls?

Steve Bliss, of BuildingAdvisor.com, writes: The short answer is: Don’t use a vapor barrier in a finished basement. This is asking for trouble, especially with a full bathroom, which generates a lot of humid air. Rigid foam board on the interior, like you have, is the ideal insulation.

How do you install rigid foam insulation on interior walls?

How to Install Rigid Foam Insulation Between Studs

  1. Measure the Project Area. Measure the entire wall area to figure out the amount of rigid foam to purchase. …
  2. Measure Individual Cavities. Measure each bay individually. …
  3. Mark and Cut the Rigid Foam. …
  4. Install the Rigid Foam Insulation. …
  5. Seal the Gaps in the Insulation.


What kind of insulation is best for basement walls?

Rigid foam sheets are best for DIYers who are insulating basements prior to framing the walls. Rigid foam also works well when the concrete or block walls are smooth and flat. Rigid foam insulation is easy to use. In addition to scoring, it can be cut by an ordinary wood saw.

How much space should be between studs and basement walls?

Be sure to maintain the 16-inch on-center stud spacing, and check the wall frame to make sure it’s plumb before nailing it to the beam.

Should I Drylock my basement walls?

Of course, the reason you need to seal any basement foundation is because the foundation is porous. Moisture can come through the concrete, stone or block and cause a lot of problems under the house so sealing it is an integral part of the process in making sure your basement is clean and dry.

Do you need a vapor barrier with rigid foam insulation?

Foam insulation usually does not require a vapor barrier. For some foam insulation types, such as closed-cell spray foam and foam board insulation, the insulation itself stops the movement of most water vapor.

How do you get moisture out of basement walls?

You can air out the basement by opening windows and running fans to circulate the air. You can also try turning up the heat in the basement, as warmer air will prevent moisture from condensing on cool surfaces. Another solution is to use a dehumidifier in your basement.

Should you seal basement walls before finishing?

Nothing will ruin a beautiful remodeling job like soaked carpets, moldy drywall and damaged furniture so it is essential that a basement be fully waterproofed before any finishing work begins.

Will insulating basement reduce humidity?

Insulating your basement cannot reduce the humidity because it is designed to help control temperature. Insulation can help reduce humidity by keeping the air colder or reducing condensation by keeping the air warmer. However, it cannot change the moisture levels in the air.

Is foam board a vapor barrier?

Rigid foam board, especially foil-faced polyisocyanurate, creates a vapor-impermeable barrier, so the wall would have limited drying potential. Even more permeable types of insulation, such as expanded polystyrene, are vapor barriers when the installation is thick enough.

Do i need foam board in basement?

Quote from the video:
Quote from Youtube video: Also called extruded polystyrene XPS or poly iso insulation rigid foam boards create an excellent vapor barrier along with an insulation layer that will not promote mold growth.

Does rigid insulation need to be covered?

Rigid foam insulation, whether it is expanded or extruded polystyrene, does have to be covered if it is installed in the interior of a building. This wall covering must have a minimum fire rating to protect the insulation from quick combustion during a fire.

Is foam board good for basement walls?

Extruded polystyrene foam board (XPS)



XPS foam boards are naturally semi-permeable, which makes them a common insulation material for basement walls. It uses recyclable materials in manufacturing and is available in faced and unfaced versions. Its special properties make it a vapor retarder but not a vapor barrier.

Is rigid foam insulation waterproof?

Is Rigid Foam Board Waterproof? Technically, EPS and XPS rigid foam board insulation are considered to be water-resistant. A product branded as waterproof means that it offers complete impermeability, even if permanently immersed in water.

Does rigid insulation absorb water?

While XPS and polyiso rigid foam insulations absorb less water over the course of a 24-hour submersion, they hold that water much longer than their EPS counterpart does.

Does insulation board absorb water?

Due to its closed cell structure, rigid polyurethane insulation is barely affected by water or moisture: it does not absorb or transport water, i.e. there is no capillary action, and so normal moisture in buildings does not lead to any increase in thermal conductivity.

Does foam board insulation mold?

Foam building insulation, in both spray foam and foam board products, is resistant to mold growth but as we will explain here it is not absolutely mold-roof, and on occasion we do find mold growth on the surface of even closed-cell foam, in open-celled foam (rare), and on th surface of EPS and other foam insulating …

Does rigid foam board mold?

As demonstrated by recent testing, expanded polystyrene rigid foam insulation is a non-nutritive source. Mold is as common as the air we breathe.

Can mold grow on rigid foam?

Spray foam insulation would have prevented the spread of moisture, as it does not retain moisture. Since it also contains no organic material, mold cannot grow on it.