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Damp Underfloor Crawlspace
Many
homes have a damp underfloor crawlspace and some homeowners want to
know..."can I install a fan to push or pull outside air through the
crawlspace to dry the area?". Well the
correct answer is...maybe. It depends on one very important
factor...is the outside air drier than the air in the crawlspace. If
the answer is yes, then you might be able to achieve some drying by increasing
air flow from outside. But how do you know if the outside air is
drier or wetter than the crawlspace air? It is simple...calculate the dew point temperature for outside air and
crawlspace air, then compare the two.
What is
"dew point temperature"? As air is cooled, its ability
to hold moisture vapor becomes less and less until finally it reaches the
point of saturation. If the air is cooled further, condensation (dew)
will occur. In other words...if you slowly
lower the temperature of air (as in a crawlspace), there is a point (if
cooling continues) where the crawlspace air would no longer be able to hold
its moisture and condensation would occur (usually on wood members since
their temperature is often below the dew point). The lower
the dew point temperature...the dryer is the air.
1. Measure the temperature and humidity in the crawlspace and
then outdoors.
2. Use the calculator below to determine the dew point
temperatures.
3. The lower the dew point temperature...the dryer the air.
4. If the air in the crawlspace is dryer than outdoors...take
no action.
5. If the air in the crawlspace is wetter than outdoors...call
us.
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Enter
the air temperature and relative humidity into the appropriate boxes
Click
"Calculate" to display the air’s dew point
temperature
(and the approximate base height of cumulus
clouds)
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