Basement Floor Insulation Considerations


Basement floor insulation requires much consideration when you are planning improvements or remodeling your home. The basement can be a dank and damp place, depending on the area in which you live.

It can also be highly susceptible to flooding. There are ways to protect your basement from extensive water damage and prevent it from breaching the foundation of your home. Check with experts for advice on your particular home.


Each home is different; each set of circumstances will differ. There is no one specific solution for every single home; therefore, you must be aware of the conditions your own home is in. If your basement will be ‘finished’ and actually used as an extra room in your home, you need to think about dampness protection. Certain climates have unique conditions which will dictate the level of insulation required.

The depth of the basement compared to the foundation of the house will also be a major factor. Dampness protection is the most vital protection that you will need. Even if the climate in which you reside is dry and warm most of the year, you might still have issues with condensation and dampness in the dark underground places. Your basement may be merely a small crawlspace that cannot be utilized as a room that needs consideration too.


If your basement has a concrete slab floor, then you should carefully consider installing a vapor diffuser layer, which will prevent water and damp damage from coming through the foundations of your floor and damaging the basement area. Plastic layers and water retardant materials are usually used between the floor layers to keep out water vapor.

You may need to construct a raised floor to separate the concrete and vapor membrane to allow for air circulation. Always use pressure-treated wood for the floor joists; pressure-treated wood will stand heavier abuse than untreated wood.

Lay shorter cross members to support the floor. You can opt for blanket insulation under the floor of your basement to block moisture and keep the warmth. If your subframe is a grid, you will have to cut the blanket insulation to squares in the size of the spaces, then placed the floor on top.

You can use foam board insulation to protect your basement. Foam boards are rigid insulators that provide excellent thermal insulation. Most foam boards are polyurethane or Styrofoam and offer a firm base of protection against moisture accumulation.

Lay plywood sheets to create a subfloor over the insulation. Pressure-treated plywood is the best type because it better resists damp, cold, and wet conditions.


Basement floor insulation will not prevent your home from flooding, but it will prevent the damage from becoming totally unmanageable. There are varying degrees of flooding. Anything over 2-inches of water is considered a flood.

Unless your basement has excellent drainage, you may find that the water will have no way to exit the space. In such an event, it will seep into the floor, causing serious damage. Blanket insulation will hold water and expand if it is exposed for too long of a period.