|
Home
Services
Photos
Contact Information
Tips for Property
Owners
Resume
Links
Search
| |
Crawl Space Ventilation
Another area of a house, which must breathe for its well being,
is the crawl space. Lack of proper ventilation in a basement or crawl space is
frequently a problem. The use of dehumidifiers during the warm months of the
year is beneficial in assisting the removal of moisture from the air.
Circulation of the air also helps reduce problems, assuming the volume of air
being moved is consistent and sufficient.
Crawl spaces can add considerable moisture to a house. A vapor barrier of 6 mil
polyethylene laid over the earth in the crawl space area with a minimum of
joints, or overlapped joints a minimum of 24 inches if necessary, is generally
recommended. To be effective, vapor barriers must be continuous. Installation of
paper or foil-faced insulation between the floor joists will also retard
infiltration of moisture into the house. The vapor barrier on the insulation
should be placed against the heated side or the subflooring.
In the summer months, the outside air will typically be 15 to 25 degrees warmer
than the air in the crawl space. This will cause the humidity to rise in the
crawl space, because warmer air has more ability to hold water than cooler air.
In dryer climates, this may not be important. However in coastal and northern
climates, depending on the conditions in the crawl space, moisture may reach its
dew point, which makes a case for ventilation. With proper ventilation, the
saturating air in the crawl space will be diluted and the relative humidity
controlled.
Tips for Homeowners
If there is a dirt floor in the crawl space, a polyethylene vapor barrier should
be installed to keep moisture from migrating out of the soil.
Exhaust vents (kitchen, bath, dryer, etc.) should not terminate in a basement or
crawl space but rather should terminate to the exterior of the structure.
The space between the bottom of the floor joist and the earth under any crawl
space should be 18 inches.
The foundation wall around the crawl space must be provided with ventilation
openings through foundation or exterior walls. These consist of screened vents
and the ventilation openings require a net area of ventilation not less than one
square foot of clear air for each 150 square feet of crawl space area. One
ventilating opening must be located within 3 feet of each corner of the
building.
Back
|
Jansen | Kiener
Your Solution