Waterproofing Questions, Answered

Angi's and HomeGuide's 2026 typical-project range is $2,300 to $7,600, average about $5,000; a full interior perimeter drain and sump system runs $5,000 to $15,000, exterior excavation $10,000 to $30,000 or more, crack injection $250 to $800 per crack, and a sump pump install $1,000 to $3,000. Rockland interior systems usually sit in the upper half of national ranges.

For an existing Rockland house with seepage, an interior perimeter drain with a sump and backup handles groundwater at a fraction of the cost and disruption of digging. Exterior is for failing walls, new construction, or one accessible wall that is the whole problem.

No. We are a free referral service for Rockland County homeowners. You tell us what the basement does; we pass it to an independent, licensed and insured local waterproofing contractor who serves your town, and they quote you directly. We never charge you anything.

Cutting the slab for a drain and sump, and excavating against the foundation, are commonly permitted in Rockland towns and villages; grading, downspouts and crack injection usually are not. The contractor applies.

No. Homeowners policies exclude groundwater seepage and do not cover prevention. Sewer backup needs its own endorsement; flooding needs flood insurance. Waterproofing is a maintenance investment, usually recovered at sale.

The Rockland County home improvement contractor license (Chapter 286 of the county code), which requires insurance. Ask for the license number and a certificate of insurance naming you before work starts.

Surface water shows up during or right after rain, often at a specific spot below a downspout or window well, and stops when the rain stops. Groundwater comes in hours or days later, along the whole cove joint or through the floor, and keeps coming in a wet spring. Fix surface water first; groundwater needs a system.

The seam where the basement floor slab meets the foundation wall. Under hydrostatic pressure, groundwater pushes up through it; an interior perimeter drain sits right at that joint to collect it.

The drain and pit, indefinitely; reputable contractors give transferable lifetime warranties on them. The pump is a wear item: seven to ten years, test twice a year.

Humidity: block walls and slabs wick moisture that evaporates into the air even without visible water. A dedicated dehumidifier draining to the sump, kept under 50 percent relative humidity, usually fixes it; if there is mold behind finished walls, that is a separate, licensed job.

The bottom 12 to 24 inches of finished wall along the perimeter comes off for an interior drain; the rest stays. Contractors cut cleanly and most homeowners have a carpenter close it back up after.

Damp-proofing is the thin coating applied to the outside of foundations at construction to slow moisture; it does not stop water under pressure. Waterproofing is a system (drainage, membranes, pumps) that handles water.

We read your request and pass it to one independent, Rockland County-licensed and insured waterproofing contractor that serves your town. They contact you, usually within a business day, to look inside and outside and give a written quote. You decide; there is no fee and no obligation.

An independent local contractor, never this website. We do not do waterproofing, we do not take payment, and we have no stake in which company you choose.