If you have a home sitting on a crawl space foundation, you probably heard from many sources that crawl spaces need vents to allow the air to circulate and dry the ground moisture.
You might have been instructed by the local building code inspectors to provide a certain amount of vents, and lay some plastic on the floor to curb some of the ground moisture.
With all that in place, your crawl space remains something you dread. You’ll do anything in your power to avoid crawling in there, and the very thought of it gives you the creeps. It is a dark, damp, bug infested, and mold ridden place. Heaven only knows what else is getting into it through those vents!
You did everything up to code, so you think that this is just how crawl spaces are supposed to be and look like. And sometimes you secretly wish you had a home with a full basement or on a slab, instead.
You are consoled with the idea that as bad as it is, you hardly go there at all, therefore, the filthy crawlspace is definitely something you can live with… most of the time, at least.
What you do not know is that your vented crawl space is costing you a whole lot of money. Surprised? Let me count the ways in which you might be literally throwing money out of those vents:
It may sound like common sense to open vents in the crawl space to dry it out. However, there is no scientific evidence that crawl space vents actually do that job.
There is, on the other hand, plenty of scientific evidence to the contrary: crawl space vents actually aggravate moisture problems.
“How could that be possible?” you might be thinking. After all, everyone knows that air helps dry things, right?
Well… not in the crawl space.
Allow me to explain:
During the summer, due to temperature differences between the crawl space and the outside, any moisture present in the outside air as it enters the colder crawl space, increases at a rate of 2.2% per degree it is cooled. As a result the relative humidity (RH) in the crawl space is always much higher than the levels in the outside air.
High levels of moisture in the crawl space favor mold growth. Mold feeds on organic matter. It causes wood to rot, which eventually leads to rotten floor joists and subfloors, bucked floors, and serious structural damage. In other words, as you read this, your home’s structure may be being eaten by mold.
Moisture also attracts pests like termites, carpenter ants and mice. Soft wood provides food and perfect nesting conditions for many critters. No need to elaborate on the damages these bugs and rodents cause.
Due to a physics phenomenon called the “stack effect”- which refers to way the air moves in buildings - the air in the crawl space is consistently being sucked into the upper levels of the house. Here’s a little graphic illustrating that phenomenon.
As the air inside the house is heated, it rises and escapes through openings in the upper levels of the building. The supply is then replenished with air sucked in from the lower levels. About 1/3 of the air you breath in your home is coming from the crawl space. If that air has mold spores and dust mite pellets in it, you and your family are breathing them. These are the two most common triggers of indoor allergies.
If you and your family are having indoor allergy symptoms, such as stuffy or runny noses, itchy or watery eyes, asthma or other breathing problems, your crawl space may be to blame.
4 – Vented Crawl Spaces are Not Energy Efficient
Besides all the health related problems, a vented crawl space may be costing you a lot of money in utility bills. Humid air is much harder to cool or heat, and since the moist crawl space air is consistently infiltrating the building envelope, your HVAC system is working harder to keep the temperature comfortable year round. Things get even worse if you have ducts running through the crawl space. Energy losses in that case can be as high as 50%! In other words, you are wasting about half of the money you pay to cool and heat your home.
Crawl Space Encapsulation
Crawl Space Encapsulation is a newer crawl space treatment technology proven to effectively control moisture, prevent moisture related problems and cut energy losses.
It consists of lining the crawl space with a sturdy vapor barrier to completely isolate it from the outside air and ground moisture, and then conditioning the space with a powerful dehumidifier or a crawl space conditioning device. Through this process, the crawl space becomes part of the internal building envelope.
Ground breaking studies conducted by Advanced Energy, in conjunction with Habitat for Humanity, as well as studies conducted by Building Science Corp. demonstrate that encapsulated crawl spaces improve a home’s overall energy efficiency by an average of 18%.
The improvements in terms of moisture are so significant that encapsulation is now recommended as Best Practice by the U.S. Department of Energy’s Building America initiative.
Crawl space encapsulation is a small investment that will pay for itself in home energy savings alone, besides protecting your home’s structural integrity, and improving indoor air quality.
Now think, can you really afford to leave your crawl space unprotected?