Long Island Foundation Waterproofing
Exterior waterproof membranes designed for Long Island's water table and coastal climate, keeping seepage and dampness out of below-grade spaces.
What is Foundation Waterproofing?
Exterior foundation and basement waterproofing designed specifically for Long Island's coastal moisture and high water tables. We apply durable waterproof membranes to permanently protect your below-grade spaces from seepage and dampness.
The waterproofing scope
From open wall to a coated foundation
Expose the concrete, prep it, spray the membrane, then backfill.
Step 01
Expose the exterior wall
New construction leaves the wall open before backfill. On an existing house, we excavate the perimeter so the concrete is reachable.
Step 02
Prep the concrete
Dirt and loose material come off the wall so the membrane bonds to a clean surface.
Step 03
Spray the membrane
A continuous waterproof coating goes on the exterior face, covering the wall that will sit against the soil.
Step 04
Backfill
Once the coating is on, the excavation is filled back. The membrane stays between the soil and the concrete.
Where it goes
New walls, existing foundations, and below-grade space
The waterproofing membrane goes on the exterior of the foundation. On new construction we apply it before backfill. On an existing house we apply it after excavation.
New construction, before backfill
The exterior wall is still open. We spray the membrane before soil goes back against it.
Existing foundations
Remedial work excavates around the perimeter. The same sprayed membrane goes on once the wall is exposed.
Below-grade living and storage
Finished basements and unfinished storage both stay drier when water never reaches the concrete.
How the wall stays dry
Water stops on the outside of the wall
The coating sits between the soil and the concrete, so Long Island groundwater meets the membrane instead of the basement.
Membrane on the exterior wall
A sprayed coating on the outside of the foundation, applied while the concrete is still open.
Water stopped before the concrete
Interior sealants only manage water that has already come through. The membrane keeps it out of the wall.
Basements and storage stay dry
Finished rooms and plain storage both stay protected from seepage, dampness, and long-term moisture damage.
- Closed-Cell SprayFoam Insulation
- InteriorBasement Space
- Poured ConcreteFoundation Wall
- Footing
- Seamless, Spray-AppliedWaterproofingMembrane
- Crushed GravelWeeping Bed
Local crews
Waterproofing crews Long Island already calls.
KC Insulation is a family company out of Central Islip. The same crews spray exterior membranes for homeowners and for general contractors who need the foundation coated before backfill.
- 2003
- Family owned on Long Island since
- Central Islip
- Shop and home base
- Nassau & Suffolk
- Homeowners and general contractors
Service area
Waterproofing across Nassau and Suffolk
Crews leave Central Islip for foundation jobs from the South Shore and Nassau through Smithtown, Brookhaven, and the East End.
Central Islip and across the island
- Central IslipHome base
- HuntingtonSuffolk
- Bay ShoreSuffolk
- SmithtownSuffolk
- BabylonSuffolk
- HempsteadNassau
- PatchogueSuffolk
- RiverheadSuffolk
- SouthamptonEast End
- East HamptonEast End
More Services
Explore our other services
From insulation to waterproofing, KC Insulation Corp handles every phase with the same disciplined standard.
FAQ
Common questions about waterproofing.
Exterior waterproofing stops water at the source, before it reaches your foundation wall. Interior solutions like sealants or drainage systems only manage water that's already penetrated, leaving your concrete exposed to long-term moisture damage, efflorescence, and structural degradation. On Long Island, where water tables run high and coastal moisture is constant, exterior membrane application is the most effective defense.
Don't wait! Get a free estimate. Secure your spot today.
We want to make the process as easy as possible for you. Contact us today to get a free estimate.