A crawl space is a basement that is so low that a person cannot walk in it. It is designed to promote air circulation and to provide access to pipes and other structures under the house that cannot be accessed otherwise. It cannot be converted into a usable living space, but it often used for storage. However, as a storage area, care must be taken to prevent moisture damage. Crawl spaces can also harbor insects and vermin, which can damage the home from below. Crawl space encapsulation is a way to protect the underside of the house from moisture damage, insects, and other unwelcome guests.
Crawl spaces are primarily made up of dirt and concrete.
Both are permeable to moisture, causing this area beneath the home to become moldy. The cost of crawl space encapsulation systems averages from $5000 to $7000. Crawl space encapsulation cost for these systems starts as low as $2000 and can go as high as $14000. Variables that affect the price include the materials used and the size and condition of the crawl space. Previously, moisture control was done through venting the space, allowing for moisture to escape. However, it is now understood that venting actually allows moisture in, especially in humid regions such as the southeastern United States.
Crawl space insulation is a way to cut down on energy costs. For unvented crawl spaces, the most appropriate method is to insulate the concrete walls, and not the dirt subfloor. Only insulating the walls will cut the amount of materials, and the crawl space encapsulation cost, in half. With both vented and unvented spaces, however, it is still recommended that a vapor barrier be used. A continuous termite shield should also be installed to prevent infestation. Also, any air leaks must be sealed. Crawl space insulation should be considered as part of an encapsulation project.
Waterproofing a crawl space is important not only to the structure but to the health of the occupants. Moisture build up allows for the growth of mold and fungi. As warm air rises through the home, it brings with it the mold and fungi from below, which are hazardous to the health of the home dwellers. Moisture can also result in significant and catastrophic water damage to the joists and other sub structures beneath the home. In addition, a dry crawl space is less inviting to insects, rodents, snakes, and other invaders that thrive in dark and wet environments.
The sealed crawl space cost will be quickly paid for by the significant energy savings in the home, as the conditioned air will no longer be able to escape the home from underneath. A properly sealed and well insulated crawl space will both decrease total home energy costs and increase the comfort level inside the home. The Energy Star web page states that a homeowner can save 20% on the cost of heating and cooling the home, and 10% on total energy costs by air sealing the home and insulating attics and crawl spaces.
Most crawl spaces are built with a dirt floor instead of concrete. Some home builders choose to forego a crawl space for a concrete slab foundation instead. This kind of construction, however, generally diminishes the home’s value. In addition, there is much to be said for the accessibility gained with the addition of a crawl space. A crawl space also tends to keep a home warmer in cold climates than a concrete slab foundation. Pouring a concrete floor in a crawl space is an option to make the area more usable as a storage area, but concrete does not prevent moisture and a vapor barrier will still be needed, adding to the crawl space encapsulation cost.
Crawl space repairs can be immensely expensive. The labor required is physically difficult, as most of the work must be done while laying on one’s back. Sources of damage range from moisture and mold to damage from rodents and termites. Rodents can create holes and other damage my gnawing away at wooden substructures. Termite damage can be devastating, requiring the replacement of floor joists, floor beams, and sometimes the entire floor framing system. Costs for this repair can run as high as $30,000 and higher depending on the extent of the damage.
Dehumidifiers are often installed in crawl spaces and basements as they tend to be the dampest areas of the home.
Dehumidifiers for crawl spaces can add to crawl space encapsulation cost at $800 to $1200 or more per unit depending on their capacity. They are relatively easy to install as a do it yourself project. Professional installation can add $100 to $400 to the cost of the project.
Encapsulation is generally achieved with the installation of a vapor barrier. Crawl space vapor barrier cost is determined by the thickness of the plastic liner being used. A 6-mil plastic liner will provide the lowest crawl space vapor barrier cost. Other less expensive choices are 8-mil, 10-mil, and 12-mil. The priciest crawl space vapor barriers are liners with a 20-mil or 23-mil thickness. These more expensive alternatives might also include the installation of a sump pump, especially for crawl spaces that are beneath the water table, to remove accumulating water. Dehumidifiers might also be installed.
The cost of installation of a crawl space barrier is primarily determined by the thickness of the plastic liner being used. The most popular encapsulation systems use a 23-mil barrier that is treated on the bottom with a fungicide and a mold retardant. This type of encapsulation system is available from authorized contractors for a crawl space encapsulation cost ranging from $4000 to $14000 depending in large part on the square footage of the space. These systems, especially the more expensive variety, generally also include the installation of a dehumidifier for added moisture control.
Building a concrete crawl space instead of a basement can save money when building a house. Constructing a basement instead of a crawl space can add $5000 or more to the cost of building a home. The advantage to a basement instead of a crawl space, however, is that the value of the home is more due to the added living space. In addition, a basement can later be converted into a comfortable and usable living space while a crawl space cannot. On the other hand, a concrete slab foundation would be less expensive than a crawl space.