Service
Wet basement: find the cause before paying for a fix
Three different things make a basement wet, and the repair for one does nothing for the others. An hour of looking can save a system you did not need.
Three kinds of wet
From the air
Condensation
Beads of water on cold pipes, a damp film on the lower walls, a clammy floor in July and August. Nothing is leaking. Warm, humid outdoor air is touching surfaces that are cooler than it is and leaving its moisture behind.
Through the wall
Seepage
Dark patches that spread after rain, white salt on the masonry, paint that blisters low down. The soil outside is wet and the wall is acting like a wick. There may never be a puddle.
From below
Ground water
Water on the floor itself, starting at the wall joint or a floor crack, a few hours to a day after heavy rain. The ground has filled up and is pushing water in from underneath.
The plastic square test
Dry a patch of wall with a towel. Tape a square of clear plastic or kitchen foil over it, sealed on all four edges, and leave it two days.
Moisture on the room side of the plastic means condensation: the air is the problem. Moisture underneath it, against the wall, means seepage: water is coming through the masonry. Do the same on the floor. It costs almost nothing and it is the first thing to tell a company when you call.
Summer air is the usual culprit
In a Montgomery summer the air outside is far wetter than the air in a cool basement can hold. Opening the windows to air the place out brings more water in, not less. If your basement is only damp in the hot months, shut the windows, run a dehumidifier that drains to a sink or the sump, and insulate cold water pipes that drip.
That alone ends a good share of musty basements, and no waterproofing company is needed for it.
A sensible order to work in
Outside first
Clean the gutters, carry each downspout out into the yard, and pull mulch and soil back so the ground slopes away from the wall.
Test and dry the air
Do the plastic test. If it points to condensation, run the dehumidifier for two weeks and see what is left.
Watch two storms
Note where water shows, how long after the rain, and how far it spreads. Take photos.
Then call
If the walls still darken or the floor still gets wet, you have seepage or ground water, and it is time for someone to look.
What each cause leads to
Seepage through a wall is handled from outside where that is practical, by grading and drainage or a membrane on the wall. Those are covered under exterior waterproofing. Ground water at the floor is collected by an interior drain and pumped out. Water at one spot is a leak repair.
Many basements have two of the three at once. A good inspection says which, in writing, before it says what to buy.
While you are waiting
Get cardboard boxes off the floor and away from the walls. They pull moisture out of the concrete and mold starts there first. Use plastic bins on a shelf or a pallet. Keep an eye on the bottom of any wood stud wall, and on the feet of the furnace and water heater for rust.
Wet basement questions
Is the white powder on my wall mold?
Almost certainly not. Mold is fuzzy or slimy, dark or green, and grows on things it can eat: paint, paper, wood, dust. The dry white crust on bare masonry is mineral salt left by evaporating water. It is harmless in itself, and it is a reliable sign the wall is passing moisture.
Should I finish the basement and deal with damp later?
Do it the other way round. Framing, insulation and drywall against a wall that seeps will hide the problem until it smells. Get the cause identified and fixed, live with it through a wet season, then build.
Montgomery and nearby towns
Ready to have someone look at it?
Call and describe what you are seeing and when it happens. You will be put through to an independent local waterproofing company, and they arrange the visit with you.
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