Why Crawl Space Encapsulation: Benefits, Negative, and Costs

Homes built on a pier and beam foundation or with small crawl space type basements often suffer from cold floors, dampness, or moisture invasion. Pest management is often another reason for encapsulating a crawl space beneath a house. However, crawl space encapsulation is not always a good idea. You should consider the cost, benefits, and negatives of crawl space encapsulation before making any decisions.

Crawl spaces often encourage damp environments beneath your home that can foster inspect and rodent pests. Mold and mildew in your home are often associated with moisture that enters through the crawl space. The efficiency and effectiveness of your HVAC system can also depend on the condition of your crawl space. Encapsulation can often solve these problems.

However, crawl space encapsulation is not always a good choice. Understanding how encapsulation works in a crawlspace is the key to making the right decision. If you know the negatives and the benefits of crawl space encapsulation, you are much more likely to make the best choice for your home.

An encapsulated crawl space has been fitted with special heavy-duty moisture barrier materials over the floor of your crawl space. The walls of your foundation are sealed, as are the foundation vents. Insulation is often added to the walls to increase the efficiency of encapsulation. In many damp areas, a dehumidifier is also added to the crawlspace.

When installed properly, the crawl space encapsulation system will keep the crawl space dry and add a bit of additional insulating properties to your home. The plastic barrier material keeps moisture from migrating into the crawl space area and eventually into your home.

Sealing the foundation walls and vents prevents air infiltration into the crawl space, helping moderate the humidity level and the temperature. This can reduce the stress on your HVAC system and help maintain a more consistent temperature in your home. Many people report that they no longer suffer from cold spots on the floors of their homes after having the crawl space encapsulated.

A properly encapsulated crawl space can be a major factor in controlling pests in your home. The most damaging of pests are termites. Termites must have a moist environment to survive. Encapsulating your crawlspace eliminates this moisture in your crawl space areas, depriving termites of the moisture they need to survive.

The encapsulation process also works to keep other insect and rodent pests at bay. The barrier materials inhibit pest movement from the soil into your home. A clean, dry crawl space is less inviting to pests looking for a place to call home. If the pests are not present, the problems associated with air quality are also eliminated from your home.

Homes with damp and unprotected crawl spaces often suffer from mold and mildew growth inside the home. Damp air migrating up into the home can raise moisture levels that encourage mold and mildew growth. Preventing the migration of this moisture also inhibits the growth of mold and mildew.

Mold and mildew are known health risks, and you must keep the conditions that support this growth to a minimum. Encapsulating your crawl space is one excellent means of reducing the conditions that foster the growth of mold and mildew in your home.

An encapsulated crawl space protects the foundation and supporting structure of your home. Moisture is one of the greatest threats to your home’s structural integrity. Damp and wet foundations can crumble. Wood structural materials in a moisture-rich environment can suffer rot and are more susceptible to insect damage.

Encapsulating your crawl space helps eliminate these structural problems. The reduction of the conditions that lead to structural damage lengthens the life of your home. You can also count on fewer maintenance costs in the long run.

One of the major costs of homeownership is the ongoing cost of heating and cooling your home. An encapsulated crawl space can make a big difference in how efficient your HVAC system works. Moisture entering your home from an unencapsulated crawl space puts additional stress on your HVAC system.

Once you eliminate the moisture and other contaminants entering your home from the crawl space, your HVAC faces fewer demands and works more efficiently. This translates into less run time and lowers utility bills. In some cases, these savings can be quite significant.

A well-encapsulated crawl space can make your home more comfortable and inviting. Many older homes with crawl spaces suffer from cold floors. An encapsulated crawl space helps moderate the temperature in the crawl space. The temperature moderation helps eliminate cold spots and drafts on or near the floor.

In hot climates, encapsulating the crawl space can eliminate a huge source of moisture inside your home. Warm moist air makes your home feel hotter than it may be. In addition, your HVAC system must work harder to cool the moisture-laden air.

A professionally installed crawl space encapsulation can be expensive. A well-performed crawl space encapsulation involves much more than just rolling out some plastic over the soil floor of your crawl space. The walls of your foundation must be properly sealed. Vents must be sealed and closed. Often mold and mildew must be mitigated before the encapsulation can begin.

These items are often encountered before the actual encapsulation job can begin, adding to the encapsulation cost.

Some homeowners experience problems with their HVAC systems after a crawl space encapsulation is performed. The amount of air circulating in your home may be seriously reduced after the encapsulation. This can impact the efficiency of your current HVAC system.

You might consider having an HVAC system professional look at your current HVAC system and evaluate how it will perform after encapsulating your crawl space. It is often better to make improvements or upgrades before the encapsulation process begins if underfloor ductwork needs to be modified or replaced.

In climates that are primarily warm and dry, crawl space encapsulation may not be a cost-effective option. Encapsulation of a crawl space is usually done to control moisture in the space and in your home. Areas with low to moderate rainfall often don’t benefit from crawl space encapsulation.

The advice of a professional crawl space encapsulation company is often the best way to judge the value of having your home’s crawl space encapsulated. If there are no crawl space encapsulation companies in your area, more than likely, there is not much need to encapsulate your crawl space.

On average, the nationwide cost for encapsulating the typical home crawl space averages between $3,000 and $8.000. Some larger homes or homes with challenging moisture problems can exceed $15,000 for an encapsulation project.

Some sources place the average cost at $5,500, while others place the median cost at $8,500. Regional differences can drive some of the differences, while sizes of homes are the basis for some.

Overall, we find that the average prices for encapsulating a crawl space fit into these ranges.

The need for additional foundation wall insulation is dependent on your location, climate and the construction of your perimeter foundation walls. In some cases, your contractor may suggest that rigid foam insulation be placed on the inside of your foundation walls before the encapsulation is performed.

You can expect the addition of rigid foam board insulation to cost between $0.50 and $2.00 per square foot, depending on the R-value of the insulation board. Fiberglass insulation panels are a bit more expensive. Expect to pay between $2,00 and $4,00 per square foot for fiberglass insulation boards.

The vapor barrier material is the heart of the encapsulation system. Many people opt for the cheap solution using 6-mil plastic sheeting. This material will perform the barrier job adequately, but the thin material is prone to ripping and tearing. If you plan on using your crawl space for storage, a heavier vapor barrier material is a good choice.

6-mill plastic sheeting typically costs between $0.25 and $0.35 per square foot. A thicker vapor barrier material usually runs from $0.50 to $0.70 per square foot. This 20-mil product is much more robust, and resists tears much better than the 6-mil products.

One major part of a crawl space encapsulation project is reducing and removing air infiltration into the crawl space. This usually requires sealing the exterior vents into the crawl space and eliminating any gaps in the joints around the exterior wall of the foundation.

Vent covers can be fabricated by the installer or may be purchased from local suppliers. These pre-fabricated vent covers cost around $15.00 to $22.00. Sealing gaps and cracks are usually done with a spray foam material. The cost for a can of spray foam runs between $3,00 and $7.00. Each can of spray foam will fill several hundred feet of cracks and gaps when applied properly.

If the groundwater table under your home is close to the surface, sumps and sump pumps may be required to keep your crawl space dry. In general, the average cost of installing a sump runs between $1,100 and $1.500. Some places may require a licensed plumber to make this installation which can add to the cost.

Where runoff water is a problem, the area around the perimeter of your foundation may need to be regraded to ensure that the runoff is directed away from your home. Regrading costs vary between $1,000 and $4,500 dollars.

In some extreme cases, it may be necessary to install French drains on the perimeter of your foundation to adequately move runoff water from around your home. Nationally, the cost to install French drains on the perimeter of your foundation varies from $5,000 to $18,000. The average cost nationally is about $5,000.

An encapsulated crawl space without a dehumidifier is not a complete system. Remember that your encapsulated crawl space is now an isolated volume of air. The entrapped space naturally begins to accumulate moisture to a certain degree. A dehumidifier must be installed to keep the moisture levels in the air at the proper ratios.

For the average home, a dehumidifier sized to keep the moisture levels under control will cost between $800 and $1,500. You must also figure the ongoing cost to maintain the dehumidifier. Filters must be changed, and the water trap emptied regularly.

You may need to install several dehumidifiers for large houses or opt to install a larger commercial-style dehumidifier to adequately handle the moisture loads in your crawl space.

A crawl space encapsulation project is not one that most homeowners will undertake. Working the narrow confines of most crawl spaces is not a pleasant task. It is physically demanding dirty. However, if you are the do-it-yourself type and want to save some money, you can certainly encapsulate your crawl space yourself.

Educating yourself on the techniques and skills, you will need is part of the project. The other is ensuring you have the necessary tools to perform the job. Lastly, preparing your crawl space and the perimeter of your foundation may require bringing in sub-contractors to perform some of the work.

In general, these are materials and tools you will need to gather. The basic steps for performing encapsulation of your crawl space are included.

Once you have your materials and tools, it is time to start the job of encapsulating your crawl space. In general, these are the steps that we recommend you follow to complete the job.

Start by preparing the crawl space. The floor should be clean and level with no stones or other debris that might damage the vapor barrier. If you are gluing insulation to the foundation walls, the surfaces should be free of dust and debris. This is a good time to inspect any duct in the crawl space. Pipes or drains should be checked for leaks or damage.

It is much easier to handle the vapor barrier material outside the crawl space. Trying to unroll and cut the plastic in the crawlspace is next to impossible. Measure the walls first and cut pieces of the vapor barrier to size, allowing a generous portion at the bottom to overlap the floor sections. Cut the floor sections to fit and move them into place.

Apply the seam tape to the joints. Make sure the overlap is enough to make a good seal. Where necessary, use the double-sided construction tape to seal the vapor barrier against the piers and insulation.

Install any foundation vent seals that are required. Be sure to follow the manufacturer’s directions for installing the vent seals. Use the appropriate fasteners and caulk if necessary.

Follow the manufacturer’s directions when installing the dehumidifier in your freshly encapsulated crawl space. Remember that you will need to perform regular maintenance on the dehumidifier so place it where it can be easily accessed.

To complete an encapsulation project, you should expect to spend about 8 – 10 hours per 1,000 square feet of floor space. This time can be shortened if you have additional help. More time may be required in large or complex crawl spaces.