Interior drain tile for basements that take on water
Raritan Valley Waterproofing installs interior drain tile: a perforated pipe in clean stone, laid under the edge of the basement slab, that catches water at the wall and floor joint and delivers it to a sump.
A drain under the slab, not in the yard
People often ask for a "French drain" when they mean this. We use the term drain tile on purpose, because the job happens entirely inside. Nothing is trenched across the lawn and no foundation is dug out from the outside. The pipe sits at the level of the footing, below the floor, where groundwater actually pushes in.
That depth matters in the valley. When the Raritan or the Millstone runs high, the water table under nearby houses rises with it and presses up against the slab and the base of the walls. A drain at the footing relieves that pressure before water finds the joint.
How water gets through old block walls
Hollow concrete block was the standard foundation for decades. Each block has open cores, and when the soil outside is saturated those cores fill. The water drains down inside the wall and comes out at the bottom course, right at the floor line. A fieldstone wall leaks the same way through its mortar joints.
For block walls, small weep holes are drilled into the lowest course so the cores empty straight into the new drain instead of across the floor. A dimpled plastic sheet can go up the wall to guide any surface seepage down behind it.
The install, step by step
- Clear and protect the work area, and cover what stays in the basement.
- Cut a strip of the slab along the affected walls and break it out.
- Dig the trench down to the footing and remove the spoil.
- Lay washed stone, set the perforated pipe and cover it with more stone.
- Drill weep holes in block walls and set a wall membrane where needed.
- Pour new concrete over the trench, finished flush with the old floor.
Most of the mess is concrete dust and the stone and soil carried out, so access through a bulkhead or a short stair run makes a difference.
Where the water ends up
The pipe slopes to a sump pit. If the basement already has one in a good spot, the drain can feed it; often a new, deeper pit with a sealed lid works better. The sump pump then lifts the water out through a discharge line that should end well away from the foundation, or it simply cycles back into the same soil.
Finished basements and partial runs
Drain tile does not always have to go around the whole room. If only one or two walls take water, a partial run tied to a pit can be enough, and that keeps finished areas untouched. Where paneling, drywall or carpet sits against a wet wall, the bottom of it comes off for the trench and goes back after. If you are unsure where the water starts, tracing the leak comes first.
Drain tile in the river boroughs
See every town on the service area page.