Conditioned Crawl Space: Definitive Guide December 27, 2018 – Posted in: Blog

Living in an area with a humid climate undoubtedly requires conditioning your crawl space. Keeping this particular spot in your house completely sealed will prevent a lot of problems, from keeping your utility costs down to improving the air quality in your home. Here are some of the key things that you need to know about conditioned crawl space.

What is a Conditioned Crawl Space?

A conditioned crawl space is hermetically sealed from outdoor air and its conditioning is a part of the house HVAC system. Conditioned crawl space includes a ground completely covered with a vapor barrier, with the barrier’s seams and junctions as well. Its band joist and foundation walls are usually insulated, too.

In a conditioned crawl space, a 10-mil polyethylene barrier covers the entire floor, with the sheets extending up to 12 to 18 inches up space’s foundation wall. The sheets are glued right at the overlap seams, then to the foundation wall. Insulation boards are also glued to the entire wall.

Aside from its 100% sealed conditioned crawl space construction, humidity in this small space under the house is often removed by any of three methods – dehumidifier, small exhaust fan or air mover, or a small amount of air sourced from the HVAC system.

Properly sealing this hollow area can stop you from dealing with headache-inducing problems, from mold to low-quality indoor air. If you get asked, though, about what conditioned space problems you should expect, you may throw in how more expensive it is to seal your crawl space, given the materials that you have to use.

It can also be time-consuming but if you just think about how much better off your entire home will be and the health of your family if you compare conditioned vs unconditioned crawl space, the extra cost and effort are all going to be worth it.

Conditioned Crawlspace Pros and Cons

Given the cost of conditioned crawl space insulation, it’s understandable why you would take your time before deciding whether to go for it or not. You can come to an informed decision if you know the conditioned crawl space benefits and drawbacks.

The first benefit of conditioned crawl space is that it reduces moisture.

Excessive moisture in this small spot in the house can lead to the formation of mold. When inhaled, mold can cause health issues, low indoor air quality, and cause your property deterioration. The mold problem might not only stay within the crawl space. It may spread far beyond it.

The second benefit of conditioned crawl space is better air quality.

Encapsulating the crawl space will prevent dust and allergens from the dirt underneath the crawl space to spread in the small space and throughout the house.

The third benefit of conditioned crawl space is that it prevents animals from getting into your home.

If you pay attention to all the conditioned crawl space details and ensure that every nook, corner, and hole is properly sealed, then you’ll have a well-insulated crawl space. It can help in regulating the temperature at home better, which can also reduce your utility bills in the long term.

But there are also cons that you need to pay attention to, starting with the cost of the entire project. It can definitely cost you to pay for the typical conditioned crawl space requirements. The good news is that you can determine a budget, extra preferences, and the contractor that you find. You could end up spending a thousand dollars or ten thousand dollars if you’re not careful about who you hire.

Another possible source of expense for encapsulating your crawl space is its maintenance. Your crawl space is likely filled with piping wires running through it. You have to find a reliable electrician or plumber to take care of these aspects of your crawl space. Proper maintenance is needed if you want to balance the volume of conditioned crawl space return air, which is the reason why there is a balanced pressure between your crawl space and the entire house.

With encapsulation, you may also have to deal with odors. However, this can be prevented by following all the proper steps of encapsulating the space. Moldy or musty odors often come from areas that were not properly taped or where inferior materials were used.

If you want to have a conditioned crawl space, make sure to have it inspected for damage regularly. Your inspector’s job is to check the plastic vapor barrier used in insulating the small spot to ensure that it is doing its job well.

Conditioned Crawl Space vs Vented Crawl Space

Crawl spaces are quite common in the US and most of them are vented, but it’s not the most effective way to go about keeping the area dry. Humidity will most likely cause moisture problems, which often come from leaks from the plumbing pipes, which usually run through crawl spaces. Since these areas are often neglected, the leaks can remain undiscovered for a long time.

Uncovered soil is another source of moisture in vented crawl spaces. Moisture also comes from foundation walls, where moisture from the ground outside of your house may migrate through to reach your crawl space. Foundation vents are also sources of moisture. Despite being placed to help keep the crawl space dry, it also lets water vapor from outdoor air go in, raising the humidity in the small space.

This is why it is definitely a better investment to have a conditioned crawl space. Having it encapsulated will seal it completely from all these sources of moisture, reducing the humidity in this less visited part of the house.

High Humidity in Crawl Space

To keep proper humidity level that does not foster mold in crawl space, you need to invest in certain tools. Install a dedicated dehumidifier in your crawl space and set it to 55% relative humidity. You can also install a humidistat that will ring up an alarm if the humidity exceeds 70%. This should get you to check your crawl space for possible sources of moisture instead of letting it fester in the confined space.

For conditioned crawl space ventilation, the new standard says you need to add fresh air to your building envelope at .01 CFM per square foot of the building, without forgetting about the 7.5 CFM per occupant. You can determine the number of occupants by the number of bedrooms plus one.

You can also install an exhaust fan in the crawl space to accomplish two things at once – ventilate the house and condition the crawl space.

With proper insulation and conditioning of your crawl space, you can leave it dry, bug-free, and mold-free. You can also regulate its temperature to remain the same as the temperature in the entire house.