How to Properly Ventilate Your Crawl Space
A crawl space , by its literal definition, is a shallow space beneath the first floor or the roof of a building especially meant for accessing plumbing and wiring. Ventilation refers to the flow of air in and out of a space.
Home buyers often underestimate the impact crawl spaces and crawl space ventilation, specifically, have on their homes. Although few regularly visit their crawl spaces regularly like other parts of their home, the condition of the crawl space has far-reaching effects. Crawl spaces , if not properly cared for, negatively affect the value and safety of your home.
Problems Developed Over Time in Crawl Spaces
Over time, crawl spaces can develop a number of serious problems. These small spaces can become havens for fungi, molds, mildews, and pests, as these things thrive in moist conditions.
Moisture in crawl spaces occurs when insulation traps water vapor. The dark, warm conditions thus also encourage mold and fungus to grow. These organisms can then spread throughout the entire house and cause considerable damage. Black mold is often blamed for human health issues, as well.
Requirements for Crawl Space Ventilation
Requirements for crawl space ventilation are outlined in the International Residential Code (IRC). The IRC includes rules meant ensure safety and health of all inhabitants in a house.
Ventilation
According to the IRC, a crawl space should have one square foot of screened vent for every 150 square feet of space. To further reduce moisture, homeowners can cover bare ground with an approved vapor-barrier material. The IRC also requires each corner of the building to have one ventilated opening to allow the cross-flow of air.
Ventilated Openings
The IRC states the openings in the structure’s corners should be at least one square foot in size. The following materials ensure the efficient cross-flow of air for ventilation:
- Sheet metal plates with holes no less than 0.070 inches thick
- Expanded sheet metal plates no less than 0.047 inches thick
- Cast-iron grill or grating
- Corrosion-resistant wire mesh at least 1/8-inch thick
These materials allow for the limited but proper air flow to eliminate humidity within the space and make it “breathable” in order to keep moisture from collecting. The openings at each corner of the structure allow air flow to come from multiple directions and to ensure the air flows through the crawl space efficiently and evenly.
Unventilated Crawl Spaces
Some homeowners prefer to not vent their crawl space to try and prevent thermal heat loss. Recently, the IRC allowed the option for nonventing crawl spaces if the builders mechanically circulate air between the upper, conditioned area and the crawl space. For this to happen, the crawl space floor area and foundation walls must be completely sealed with material ( encapsulation ) that slows the entry of water vapor.
Airing out your Crawl Space
Adding ventilation to a crawl space takes time, and there are several options depending on the building or foundation type. Most crawl spaces are vented to the outdoors, but over the past decade, another procedure called encapsulation has gained popularity for its energy efficiency. Encapsulation refers to the process of covering floors, walls and support structures in plastic sheeting to keep the space dry. The following are more options for venting the crawl space:
- Transfer a small supply of heated air from the HVAC system into the crawl space
- Use an exhaust fan to move air from the crawl space to the outside
- Install an air intake or dehumidifier system
Making your crawl space a safe, hazard-free environment is a complicated process with many options. The team of professionals at Yes Pest Pros can help. We’ll provide an affordable solution to keep your crawl space well ventilated and free of pests, fungi, molds, and other unwanted inhabitants. Contact us today for a free quote.
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