Keeping homes and apartments dry to reduce the chance for mold
problems in the Pacific Northwest can be a challenge. We cannot
control the weather, but we can build and operate our buildings in
harmony with our environment, and keep them dry inside even in “rain
Homes with excessive moisture are at risk for serious structural problems,
expensive renovation of damaged materials, and cosmetic problems such as
peeling paint and staining. The occupants can also be at risk from exposure
to excessive amounts of mold and other asthma triggers and allergens.
1) The first line of defense is to keep moisture out
• Make sure your roof does not leak and that it sheds
water away from the foundation and crawlspace.
• Gutters, downspouts and landscaping should direct
water away from the home.
• Check toilet, sink and washer plumbing for leaky
fittings or hoses. Replace before it may leak.
• Make sure your windows, doors and other penetrations
do not leak.
2) The second step is to limit the build-up of
moisture generated inside.
• Our homes get moist from the inside from day-to-day activities of the occu-
• Our breath contains water vapor and we perspire. The more people — and the longer
they spend in the home — the more moisture builds up.
• We cook and do laundry.
• We wash dishes.
• We bathe and shower.
• We add water to our houseplants and aquariums.
• We mop the floors and shampoo carpets.
• We track water in with our shoes and hang raincoats and towels to dry.
We cannot stop living in our houses . . . so follow these easy tips to keep your house from
getting wet from the inside out.
Keeping Homes Dry
INDOOR AIR QUALITY
We cannot stop
living in our
these easy tips to
keep your house
from getting wet
from the inside out.INDOOR AIR QUALITY FACTSHEET
1) Do not generate any more moisture than
• Reduce the number of house plants.
• Cook with lids.
• Put covers on aquariums.
• Do not hang damp laundry indoors.
• Take shorter showers.
2) Capture and remove moisture at the
• Use exhaust fans in the kitchen and bathroom.
• Make sure exhaust fans are pulling enough air
and are vented to the outside.
• Keep bathroom door closed until all the bath
moisture is exhausted.
• Make sure
clothes dryer vent is
unobstructed and has
3) Like people,
houses need to
• Exchange the moist air
inside for fresh air outside.
• Consider that 40 degree
outside air with 100 percent
relative humidity will turn into 30 percent
relative humidity air as you warm it to 75 de-
grees inside your home. (So, you can dry out
your home by “flushing” outside air even if it is
40 degree fog.)
4) Use exhaust fans.
• Exhaust fans rid the home of excess moisture
which is replaced with outside air.
5) The colder it is outdoors, the less outside
air you will need to keep moisture levels
• The warmer it is outside, the more outside air
it will take to dry a home. While this is good
news for energy use, in some mild and moist
climates a dehumidifier may be required in
addition to ventilation.
6) Keep your house and rooms warm.
• Cold surfaces will allow moist air to condense
and can quickly lead to moisture, mold and
• “Closing off” rooms to conserve heat may well
lead to mold growth in those rooms.
House Ventilation Strategies
Older homes can suffer from moisture problems when
the occupants produce lots of moisture but do not
actively remove it.
Running exhaust fans more frequently is often the
easiest solution. Make sure your home has exhaust fans
that actually work, and use them as needed to directly
capture and remove moisture and to pull in outside air.
Note: A ceiling fan or room fan does not pull in outside
While our newer
energy, they still
need to breathe in
order to avoid
Newer homes can
be less forgiving
when we do not