Why Do Homes Have a Crawl Space?
What is a crawl space and why do homes have a crawl space?
Simply put, a crawl space is similar to a basement but is vented to outside air. Some crawl spaces can be full-height like a basement, where others can be two feet tall or shorter, so that you have to crawl around on your belly.
So why do homes have a crawl space? The two primary reasons homes have crawl spaces are cost and accessibility - since crawl spaces work by allowing outside air to circulate beneath the house. By building the floor of a home off the ground (as opposed to on a concrete slab-on-grade), there are several benefits, including:
- Cost effectiveness. Moving dirt to level a sloping lot for a concrete pad can get expensive; a crawl space negates that need.
- Convenience. You get a handy place to install the HVAC unit and piping, as well as water and sewer distribution throughout the house. This also makes future repairs and replacements easier.
Unfortunately, with great cost-savings and convenience comes great responsibility. The question, "why do homes have a crawl space" can be answered negatively. Homes built over crawl spaces have the tendency to suffer from moisture-related issues because of the crawl space's surroundings (what sort of landscaping is directly outside the walls of the crawl space that is being vented inside?). Mold, wood rot, and termite infestation are often the result of moisture problems in crawl spaces. One great way to combat this is by utilizing a vapor barrier and dehumidifier in the crawl space, which will greatly reduce the amount of moisture. This can drastically reduce your crawl space's risk for:
- Wood rot and structural damage
- Floor failure
- Decreased insulation R-values
- Increased heating and cooling bills
- Dust mites
- Allergy aggravation
- Poor indoor air quality
Crawl space vapor barriers prevent ground moisture evaporation from entering your crawl space air. When you couple a crawl space vapor barrier system with a waterproofing system, moisture and water can be barred from the crawl space before it has a chance to cause problems - which means no more mold, foul odors, rot, rust, insects, rodents, and other humidity- or moisture-related problems. So why do homes have a crawl space and how can a vapor barrier help fix its issues?
A vapor barrier itself is designed to resist the flow of air. By stopping air movement, it turns your crawl space into a semi-conditioned area by making the temperature close to the living spaces in your home above the crawl space. When the temperature in your crawl space is similar to the temperature in your home's living areas, your floors feel warmer in the winter.
A crawl space vapor barrier system also has been known to slow the movement of harmful gases like radon from infiltrating the soil, helping the crawl space vapor barrier system greatly reduce the levels of radon found in the home.
As the air in your home rises, it carries with it the air that was previously in the crawl space. That includes moisture and mold spores, as well as anything else that may be airborne down there. As this air rises in the home, replacement air is drawn through the vents. This replacement air is made up of unconditioned outside air that enters through vents and other leaks.
Because of that, whatever is in the air at the lowest point of your home eventually flows up into the living areas. Almost half of the air we breathe on the first floor of our home comes from the crawl space. A dirt crawl space with open crawl space vents is a never-ending source of moisture. Even if the dirt's surface seems dry, digging down a few inches reveals moist earth. This moisture is constantly released into the crawl space. So why do homes have a crawl space and how can a dehumidifier help? Using a dehumidifier can help to reign in any moisture problems as well as provide:
- Health protection.
- Pest protection.
- Increased structural integrity.
- Living space comfort.
Another common issue among crawl spaces is improper grading and a lack of rain gutters, which contributes to crawl space moisture control issues by allowing unwanted rain or ground water to enter the crawlspace. This repeated wetting of building materials day after day provides the perfect environment for mold growth, termites and structural damage under your home.
In addition to crawl space vapor barriers paired with dehumidifiers, there are several solutions you can look at when dealing with water in the crawl space include:
- Proper grading around the home directing moisture away from the structure.
- Installing, repairing or cleaning gutters and downspouts.
- Adding downspout extensions and exit lines to move water further from the home.
- Interior or exterior waterproofing.
- Installing crawl space ventilation.
More info? For more information about common places for moisture in your home, check out our related post: Crawl Space Insulation: Best Practices to Energy Efficient Crawl Spaces.