Residential Foundation Insulation Facts

Foundation Insulation

Facts Every Home Owner/Buyer Needs To Know About Residential Foundation Insulation

Nowadays, much thanks to the improvements and advancements in technology, more and more newly constructed homes have become even better in terms of energy-efficiency. Aside from the development of more energy-efficient construction materials, building techniques have also been considerably improved. Even heating and cooling systems, floor, door, and window treatments, and many other household items have been equipped with energy-efficiency-improving features as well.

One aspect of a home that is often overlooked, but has the great potential of making a home perform even better in the area of energy-efficiency is the foundation. Insulating the foundation can come with many different benefits, give that it has been done by a professional and the job has been completed properly and thoroughly.

Some of these benefits include the following:

  1. Reduces the amount of heat loss down to 50 percent.
  2. Lessens the costs associated with heating.
  3. Increases the overall comfort of the home’s occupants.
  4. Decreases the risks of condensation.
  5. Reduces the potential of mold growth, development, and spread.
  6. Increases the level of livability of rooms that are below-grade.

Types of Foundation

Now that you know more about the benefits of foundation insulation, the next thing that you need to know are the different types that it comes in. There are several types of residential foundation, including the following:

Full Basement Type

Were you aware of the fact that basements are actually insulation-capable? That’s right. You can actually have your basement insulated either outside, inside, or both. It is common for this part of the home to be insulated in the inside using traditional 2 by 4 framing, complete with wet-spray or batt insulation. Drywall is then used as a cover for the batt insulation.

Here are a few other things you need to know about insulating basements on the inside:

  1. Basement interiors can also be insulated using rigid foam. This foam insulation is then held in place by furring strips.
  2. Some homes make use of expanded or extruded polystyrene/polyisocyanurate insulation boards.
  3. Homes that are insulated with foam insulation boards are required by fire codes to be layered above with drywall.

As for exterior foundation insulation, here are the facts you need to know:

  1. The most common materials used when insulating the exterior of basements are extruded or expanded polystyrene. These are applied directly to the basement walls’ exterior.
  2. For any insulation material that is exposed above-grade, it should be covered so as to protect it from the harmful impact of the sun as well as from physical abuse.
  3. Some of the most common materials used as cover include cementous boards, stucco-like finishes, and roll-metal stocks.

You have another option, which is to make use of a foam-form foundation. Polystyrene foundation forms are some of the most common, and these are placed on traditional footings. These forms are then layered with concrete, which then results in curing. The outcome is that the concrete serves not only as the structural component of the wall, but also its thermal component.


For many people, crawlspaces are basically just basement walls that are shorter in length. To insulate these structural components, you can use either a foam-form or an exterior foam system. As for the common insulation type for crawlspaces’ interior, it is either draped or foam board insulation.

When mineral wool batts or fiberglass materials are used as the insulation, it is common for the batts to be tacked onto the sill plate. Usually, this is completed with the batts draping down, all the way to the flour. You should avoid using traditional 16- or 24-inch-wide bats, as they may create voids in between. These voids can cause the batts to perform below standard.


Are you aware of the fact that heat loss in a home is at its greatest near or at the exterior grade? So in order to combat this, you need to make sure that, if your home makes use of slab-on-grade, you insulate it. One way to do this is to use exterior foam insulation. The system should extend from the top most part of the slab all the way to the top most area of the footing.

Another good way to combat heat loss from this part of your home is to apply foam insulation in the footing’s interior. This is a must as it provides thermal breaks, which results in the prevention of thermal wicking.

As for the factors that contribute to how cost-effective the insulation is, here they are:

  1. Climate
  2. Fuel prices
  3. Heating and cooling system efficiency
  4. Foundation type used

The same factors apply when computing how much savings you can get with the insulation materials you are going to use. However, one thing remains to be true: through the application and use of residential foundation insulation, your home is going to become more comfortable and livable, with the much-needed bonus of providing safer, healthier environment indoors.

Commonly Asked Questions about Residential Foundation Insulation

Here are some more additional information that you should be aware of.

  1. Do unfinished basements still require foundation insulation?

If the floor above the basement is not insulated, yes, it needs to be insulated.

  1. Does floor insulation applied above basements or crawlspaces work as a good foundation insulation alternative?

Yes. However, if you have an HVAC system, pipes, and ducts in the basement, make sure that you have them insulated as well.

  1. Are vapor barriers necessary for the foundation wall interiors?

Yes, as long as an interior insulation is used.

  1. Does application of foundation insulation increase termite entry risks?

No, it does not. However, if there already are termites within the building, in the soil, or in the wood, you should know that infestation may take place.

  1. Does exterior foundation last for a long time?

Yes, as long as it has been properly installed and completed. Make sure that you work with professionals when having exterior foundation installed in your home.

We hope that, after reading this entry, you have realized the value of residential foundation insulation.

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