Why does rain come through a wall that was dry last year?
Water moves through a foundation when the ground outside is saturated and the pressure against the wall rises. A new path can open with a crack, a settled joint or a change in the grade.
A wall that stayed dry through a dry summer can leak after a wet spring, because the ground around the house holds more water and pushes harder. The water finds the joint or the crack that was always there but was not under pressure before. A settled joint, a root or a change in the grading can open a new path.
The first storm after a change is often the test, and the owner may see water for the first time. The reading and the entry point tell the difference between a path that is new and one that has been leaking for years.
Do gutters and grading matter for a basement wall?
They matter a great deal. A downspout that empties against the foundation or a grade that slopes toward the wall adds water to the ground that presses on it.
Water from the roof that runs down a downspout and discharges at the wall adds to the saturation of the soil beside it. The same is true of a grade that slopes toward the house. Extending the downspout and regrading the soil away from the wall are the usual fixes, and they are the owner's or a landscaper's to arrange.
The restoration record notes the downspouts and the grade as found, so the owner has a record of the outside conditions at the time of the leak.
Gutters that overflow in a storm drop water onto the same few feet of soil each time, and that soil stays saturated longer than the rest of the lot. Cleaning the gutters before the wet season is a cheap way to reduce that load, and the owner can do it without a contractor.
What is the difference between a leak and a seep?
A leak is a stream of water through a defined path, and a seep is damp through a larger area of the wall. Both are read and dried, but a leak usually has a clear entry point that can be repaired.
A leak can be traced to a crack or a joint, and a window well or a downspout often explains it. A seep covers a wider area of the wall and may come through the masonry itself. Seeps are harder to fix and often need the outside waterproofing reviewed by a contractor who works on foundations.
The readings help separate the two. A leak shows high readings at one point that fall away from it, and a seep shows readings that stay high across a broad area of the wall.
How long does it take for a wall to dry after a storm?
A block or poured wall can take weeks to dry, depending on the water it took and the weather. The readings decide when the drying can stop.
Masonry holds water deep in its mass, and it releases it slowly, so the readings are taken at several depths. The drying equipment is run for as long as the readings require, and the room is not closed until the wall is at its goal. Warm dry weather speeds the process, and a wet season slows it.
A wall that is closed up while damp will show efflorescence, a white crust, and may grow mold behind the finish. The record shows the readings at each check, so the owner knows when it is safe to finish the wall.
