Crawl space encapsulation is a fancy term for a series of repairs and improvements intended to make a crawl space cleaner, safer, and more energy efficient. The word “encapsulation” is an accurate description of the alterations made, but this process has also been called “crawl space sealing,” and “crawl space repair.”


Understanding crawl space problems

To appreciate crawl space encapsulation, it’s helpful to think about what happens in the average crawl space. In most cases, we’re talking about a dark, damp, cramped space under the house that no one ever enters. But out of sight isn’t out of mind. The mold that takes hold in a damp crawl space can send harmful spores into the air and cause important structural members (joists, sills, posts) to rot, threatening a home’s structural integrity. Insect and rodent pests can inhabit this space, even venturing into your living space from below.

What’s involved in crawl space encapsulation?

Crawl space encapsulation is sometimes referred to as “crawl space repair” or “crawl space sealing.” It’s easy to understand why these other terms are used. Crawl space problems –like dirt floors or water leakage through crawl space walls—call for repairs to be made as part of the encapsulation process. And the word “sealing” describes the process used to seal out moisture and outside air, so that the crawl space environment isn’t affected by exterior conditions.


An experienced crawl space encapsulation contractor should inspect your crawl space for free, and provide you with a free estimate to complete the encapsulation process. One of the details that an inspection will reveal is the structural integrity of your crawl space, including walls, joists, posts, and beams. If the main floor of the house has settled, or if the floor shows signs of unevenness, this can be due to inadequate structural support in the crawl space. Before the encapsulation process can begin, the contractor will want to correct such problems, usually be installing new posts, or crawl space jacks.


The sealing process in crawl space encapsulation typically involves sealing all crawl space vents and access openings. At least one access opening is kept operable, but weatherstripping prevents outside moisture and air from entering the crawl space. Then the contractor will cover crawl space walls and floor with heavy-duty plastic sheet material, taking care to seal all seams with special tape. If water has been leaking into the crawl space, it may be necessary to install a French drain system and sump pump to collect water and expel it outside the crawl space. If the crawl space has been damp and/or moldy for a long time, installing a crawl space dehumidifier will effectively dry out the space. 

Crawl space structural repairs, sealing, waterproofing, and drying –these are important results of successful crawl space encapsulation. One more improvement is often recommended: crawl space insulation. By insulating the crawl space walls, the floors on the main level of the house can stay warmer in winter. Plus, your house will be less expensive to heat in the winter.


Crawl space encapsulation costs

The free estimate you receive from a crawl space repair contractor will list all the repairs and improvements that are recommended. The cost for this work will depend on various factors, including the size of your crawl space, what foundation repairs are necessary (if any), and whether or not waterproofing, dehumidification or insulation are included.