First question: rain or plumbing?
Watch when the water appears. If it shows up during or after rain and dries between storms, it is coming from outside. If it is there in dry weather, or gets worse when a tap, the washing machine or the dishwasher runs, a pipe or drain is leaking and the person to call is a plumber. A water heater relief pipe and an air conditioner condensate drain are two more indoor sources worth ruling out.
Where outside water gets in, and the usual repair
- A crack in a poured wall
- Vertical and hairline cracks are common as concrete cures. One that leaks can be injected from inside with a resin that fills it through the full thickness of the wall.
- Around a pipe or cable
- Where the water service, sewer pipe or a conduit passes through the wall, the old filler shrinks. The gap is cleaned out and resealed, from outside if it can be reached.
- Window well
- A well that fills like a bucket will leak at the window frame. It needs a drain at the bottom, clean gravel and sometimes a cover.
- Form-tie holes
- Small round spots in a row on a poured wall, left from construction. Each can be plugged individually.
- Top of the wall
- Soil or mulch piled above the top of the foundation lets water run in over the wall. The cure is outside: lower the grade.
- Wall-floor joint
- Seepage along the whole joint is ground water, not a single leak. See basement waterproofing.
How a careful company finds a leak
By looking while it is wet if possible, and by tracing stains upward to their highest point if not. Sometimes a hose is run outside against one area at a time while someone watches indoors. Mark the spot with pencil and take a dated photograph whenever you see water. It is the most useful thing you can hand over.
What to ask
- Exactly where is the water entering, and how do you know?
- Is the repair made from inside, outside or both?
- If the crack leaks again, or a new one opens beside it, what does the warranty say?
- Is there anything outside, such as a downspout or the grade, that should be fixed at the same time?