Long Island's Basement Experts Since 2011
Basement Waterproofing Long Island
Long Island's high water table and clay soil demand specialized waterproofing. Mike Costello, our BSI-certified technician, has solved water problems in hundreds of LI basements.
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BSI Certified Waterproofing
Why Long Island Basements Leak — and How We Stop It
Long Island sits on top of two major aquifers. The water table in Nassau County can be as high as 6–8 feet below grade in many neighborhoods. Add the clay-heavy glacial till that makes up most of LI's subsoil, and you have a recipe for hydrostatic pressure that pushes water through every crack and joint in your foundation.
Mike Costello, our lead waterproofing technician, is BSI (Basement Systems Inc.) certified — the gold standard in the basement waterproofing industry. He's diagnosed and fixed water problems in Levittown's post-war capes, Great Neck's older colonials, and everything in between.
Our waterproofing solutions range from simple crack injections ($500–$1,500) to comprehensive interior drainage systems ($4,000–$12,000) that permanently manage water infiltration. Every solution is designed for Long Island's specific soil and groundwater conditions.
Our Waterproofing Solutions
Interior Drainage System
$4,000–$12,000WaterGuard perimeter channel drain installed below the slab, routed to a sump pump. The most effective and least disruptive solution for most LI homes.
Sump Pump Installation
$800–$3,500TripleSafe or equivalent premium sump pump with battery backup. Critical for Long Island's storm-prone environment.
Crack Injection
$500–$1,500Polyurethane or epoxy injection for isolated cracks in poured concrete walls. Fast, effective, minimally disruptive.
Exterior Waterproofing
$8,000–$25,000Full excavation, waterproofing membrane, and drain board installation. Best for severe cases or new construction.
Window Well Drainage
$800–$2,000Window well drains connected to interior system or sump. Prevents window well overflow into basement.
Waterproofing Costs
Verified Local Work
Recent Waterproofing Jobs on Long Island
Real jobs completed by our crew across Nassau and Suffolk Counties.
Interior drainage system + dual sump pump installation on cape-style home
Exterior waterproofing membrane + interior french drain system
WaterGuard interior drainage system with TripleSafe sump pump
Interior drainage channel along all four walls, new sump pit, premium pump
Exterior waterproofing on foundation block wall — excavation + membrane + drain board
Got Questions?
Basement Waterproofing FAQs — Long Island
Long Island's high water table, clay-heavy glacial till, and aging concrete block walls are the primary culprits. Water pressure builds up in saturated clay soil and forces through block wall mortar joints, cove joints (where wall meets floor), and window wells. Many LI homes from the 1950s–1970s were built with cinderblock walls that were never designed to handle hydrostatic pressure.
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