Keep Your Home's Crawl Space Dry

There is no doubt; I live in a very wet place. Fromplastic to keep the light from vents from sprouting
November to March we get an average of nearlyseeds in the soil. The recommended thickness is six mil.
seven inches of rain a month in Olympia, WA. ThisThis plastic will help to keep moisture in the soil from
deluge can lead to many homes having standing watermoving up into the crawl space air and into the wood
under them. A one-time event may not do damage,sub-structure and the home. It is a very important part
but constant or re-occurring water "events" under yourof the moisture lowering effort.
home can cause a lot of problems.Next, check your roof. Do all roof areas have proper
Standing water can lead to moisture issues in thegutters that drain into downspouts? If gutters are
wood sub-structure. Wood rot and pest infestation aremissing or damaged, have a licensed gutter contractor
common results of moisture under a home. Like allinstall new ones. They are relatively inexpensive and
animals, wood-destroying organisms (WDO's) needan important component of your homes water control
shelter, food and water to survive. If they can find asystem.
ready source of water in your home it oftenCheck all the gutter downspouts around the home. If
completes the list of needs for them to thrive. Onethey end next to the home, extend them out away
common WDO here in Western Washington is thefrom the foundation with splash blocks or
Anobiid beetle. This is a very destructive little insectnon-perforated pipes. Depending on the grade and
and makes its home in wood with moisture contentsslope next to the home different measures will be
between 14-20%. If there is standing water under aneeded to get the water away.
home, the wood in that crawl area will likely be in thatThat leads to the next step. Check the slope and
range. Other WDO's that are attracted to moist orgrade. You want the soil around the home to slope
rotting wood include: carpenter ants, dampwoodaway from the foundation for a minimum of six feet to
termites, subterranean termites, wood rot fungus andcarry water away. Adding soil around the foundation is
moisture ants.the easiest way to achieve this but remember not to
High moisture levels can also lead to mold productionallow the siding to be closer than six inches from the
and poor indoor air quality. Most mold species requiresoil. That air space is recommended to allow the
high relative humidity or moisture content to grow. Atbottom edges of the siding to dry out. If there is not
60% indoor relative humidity (RH) air enters theroom to add additional soil a swale will need to be dug
mold-formation risk zone, which is conducive to moldout away from the foundation to allow for the proper
growth. Wood reaches this zone at about 20%slope.
moisture content. Standing water under your homeNext check the crawl area vents. Are they level with
may likely produce these levels in floor joist, sub-floorsthe ground? Can water flow into them and enter the
and even carpets above.crawl area? Many hardware stores carry concrete
The first question to answer is "is there a water issuewells designed to fit up against the foundation and hold
under my home?" You can check this out yourself, orsoil back away from these vents. Using these in some
hire someone to do a maintenance inspection of yourareas may allow you to add soil to create slope with
home.out covering the vents.
If there is a water issue, I recommend following aWith these simple measures in place, let it rain! You
logical progression of changes that will dry out thathad a base line from the last storm when there was
area and keep the water from returning. I amwater under your home. Check it again. If there is no
reminded of a problem I had with my first car. It ranwater, congratulations! You have likely fixed the
rough shortly after buying it. My neighbor was anproblem. Check it again from to time to time after big
aspiring mechanic and offered to diagnose and fix itrain events to verify that the crawl area stays dry
with me. "It's the timing chain," he proclaimed after aregardless of the weather.
quick look. We spent eleven hours in my parent'sIf you find that there is still water under you home it is
garage in freezing temperatures changing it. When alltime to call a licensed drainage contractor. Explain to
was said and done, the car still backfired and ran veryhim or her what you have done to improve the
poorly. My father came out and asked, "Did you checkdrainage and ask what they recommend next.
the distributor cap?" Replacing that five-dollar part wasWhenever hiring a contractor I recommend getting a
all that was needed to have it running smoothly.referral from a friend or co-worker. Additionally, ask
Besides never letting my friend work on my car again, Ithe contractor for references and call them to find out
learned a valuable lesson. Start with the simple,if the problem was fixed by the work performed and
inexpensive things first when correcting or fixing awhat it was like to work with this person. You only
problem. I like to mix this with another great axiomwant to pay for this service once.
when solving a house problem, go from gross toA drainage contractor will evaluate the site for
subtle. Fix the obvious things first, then move to theconditions contributing to the water problem. Are there
more obscure.slopes above the foundation that shed large amounts
If the answer is "yes, there is water under my home",of water down against the home? Was the home built
you have a baseline of information, a starting point.in a low spot? What are the soil types? Where do the
Here is a series of suggested steps to keep the areadownspouts drain? The contractor may suggest
dry in the future. I recommend doing these steps firstmeasures such as new downspout drain lines, dry
and then check to see what results were achievedwells for down spout drains, sump pump drain
after the next big rain.systems under the home, a curtain drain, etc. If the
First, make sure there is a plastic vapor barriercontractor is knowledgeable and performs quality
covering all the dirt under your home. Preferably, blackwork most water issues can be solved.