Crawl Space Insulation and Encapsulation – How is it Done?

When you think about your crawl space, what do you see in your mind’s eye? Darkness? Dampness? Mold? Pests? All of the above? Unfortunately, many of us may find just that if we hitch our courage up enough to go there.

Let’s forget that for a moment and think about the situation. Do you know that the crawl space under your house affects the way you live your life above the floors? Do you have any idea how all of them can increase the wear and tear on your HVAC unit, water heater, drainage and a lot of other things? It can even make you sick if you have poor air quality seeping up like a ghost in the night, through the floor boards.

What is Crawl Space Insulation and Encapsulation?

The result is separating the crawl space from your living space. It blocks all the problems below from making their way into your home. It will keep the air from the crawl space where it belongs.

Believe it or not, the crawl space under your house affects the feel of your home above the floor boards. Thankfully, crawl space encapsulation can improve many home problems you may have.

How is it Done?

Step 1: Get rid of all drainage problems, mildew or fire hazards.

If you see standing water anywhere, find a structural engineer or qualified company to assess and fix the problem.

Mold and Mildew growth needs to be clean up from floor joists or any other equipment. If you don’t, the mold or mildew will be trapped between the layers and may grow.

Have everything safety checked. The hot water heater, gas furnace or other heating units can cause a build-up of gas in an encapsulated space. While most homes pass with flying colors, it is still a good idea to have them checked.

Step 2: Completely seal the floor, vents, and walls.

You want to seal your crawl space from your home envelope and, to the extent possible, the outdoors. To make that happen, you’ve got to do all of the following:

  • Add a plastic vapor barrier to the crawl space floor and attach it to the foundation walls, piers, and equipment. This will help keep moisture out. Also attach foam board to the crawl space door.
  • Add a thermal barrier to the crawl space walls. Again, this keeps outdoor air outside where it belongs.
  • Air seal all the gaps and cracks. The next step is to seal off all remaining gaps and cracks with spray foam.
Step 3: Keep the crawl space dry.


To sum it up, this does seem like a lot of work, and it is. But the benefits will be worth it. Your floors will be cooler in the summer and warm in cool months. The HVAC system will work better and give longer service. You save money on energy bills. Say goodbye to mold and other pests. By insulating and encapsulating your crawl space, you will benefit in so many ways. You’ll wonder why you’ve not done it before now.