Interior Basement Waterproofing in Schenectady

• What it is
• How it goes in
• When it's right
• When it isn't
• On older walls
• Cost
• Questions

What it is, and what it isn't

The principle is old and sound: don't fight groundwater, give it a better route. A channel is cut through the perimeter of the basement floor, perforated pipe is bedded in washed stone alongside the footing, and everything falls by gravity to a sump pit where a pump lifts it clear of the house.

What it does not do is make the wall waterproof. Water still arrives at the outside of the foundation. The system catches it below floor level so it never has reason to come up through the cove joint or the slab. On a poured wall that distinction is academic; on a Schenectady rubble wall it is the whole conversation, because the wall will still carry moisture and still feel damp in a wet spring. Understanding that before you buy prevents the most common disappointment in this trade.

How it goes in

1. Layout and protection. Perimeter marked, contents moved or sheeted, plastic hung to contain concrete dust. Ask about dust control before hiring anyone — cutting a slab in an old house with forced-air heat will put fine gray dust through the whole building if nobody plans for it.
2. Cutting the slab. A 12 to 18 inch channel is saw-cut around the inside perimeter and broken out. This is the loud day.
3. Excavating to the footing. Soil removed beside the footing, never beneath it. On rubble walls this is done in shorter sections to avoid disturbing the bottom course.
4. Setting the drain. Four-inch perforated pipe laid in washed stone, wrapped in filter fabric so silt can't clog it, pitched toward the sump.
5. Wall drainage. On block, weep holes are drilled into the bottom course so water sitting in the cores can escape into the drain. On any wall, dimpled board runs from footing to the top of the wall to catch seepage and route it down.
6. The sump. Pit cut, perforated liner set, lines tied in, pump, check valve, sealed lid, discharge routed at least ten feet out and pitched so it drains rather than freezing solid in January.
7. Re-pouring. Concrete back over the trench, floated flush. It will read as newer than the surrounding floor — nobody matches fifty-year-old concrete — but it should be level with clean edges.
8. Testing. Water run through the system to confirm flow and pump operation before the crew leaves.

One to three days for most basements here. Finished basements take longer, because the finishes come out first and go back afterward.

When it's the right call

• Water appears along the floor-wall seam, particularly on more than one wall.
• Water comes up through the floor or a floor crack with no wall defect to blame.
• The problem persists for days after rain rather than stopping when the rain does.
• Exterior excavation isn't practical — and on the older city lots, between narrow side yards, mature plantings and neighboring houses close by, frequently it isn't.
• You need it done in winter. Interior work carries on regardless of frost, which matters when our heaviest groundwater arrives with the thaw.
• The basement is unfinished, so there's little to lose and the price sits at the lower end.

When it isn't

• When it's surface water. One corner leaking with a downspout discharging at that corner is a forty-dollar problem. A perimeter system also solves it, in the way a sledgehammer also opens a walnut.
• When the wall is moving. Horizontal cracking or a measurable bow means stabilizing comes first. Cutting the floor at the base of a wall under lateral load without bracing it makes things worse. Structural repair first.
• When the water is the river. Overland flooding isn't groundwater and a perimeter drain won't hold it back. Read this instead.
• When you want dry walls. Interior drainage keeps the floor dry. On stone and block the wall stays damp. Dry walls means exterior work.

On rubble and early block walls

Two adjustments matter on the older housing stock here, and they're worth asking any contractor about directly.

First, sequencing. Excavation beside a rubble footing is done in shorter runs, because these walls rely on lateral support and removing it along the full length at once invites stones to move. It's slower and it's the correct way to do it.

Second, combining trades. If the wall also needs repointing — and on a leaking rubble wall it usually does — doing it while the floor is open and the base of the wall is exposed is substantially cheaper than a separate visit later. A contractor who quotes drainage on a rubble wall without mentioning mortar has looked at the floor and not the wall.

What it costs

Toward the top of the range: finished walls to remove and rebuild, a thick slab, a boiler or tank sitting in the trench line, a tight turning staircase, or a rubble foundation with an irregular footing. Toward the bottom: open unfinished basement, standard slab, bulkhead access. Full context on the cost page.

Questions about interior systems