Frequently Asked Questions

Yes — always. Every estimate is completely free, no obligation, no pressure. We come to your home, do a thorough inspection, and give you an honest assessment of what's going on and what it will take to fix it.

Call 516-920-2543 or fill out the form on our contact page to schedule yours.

Every home is different. The right solution — and the cost — depends on the source of the water, the size of the area, the severity of the problem, and which system is actually needed. There's no honest flat-rate answer.

What we can promise: transparent pricing with no surprise charges, and a real number before any work begins. Call 516-920-2543 for a free, no-pressure estimate tailored to your specific situation.

Typically within a few days of calling. Many customers note we schedule faster than other contractors on Long Island. For emergencies — flooding, active water intrusion — we respond same day. Call 516-920-2543 to get on the calendar.

Long Island's high water table and heavy storm frequency make basement water intrusion extremely common. The most frequent causes:

• High water table pushing up through basement floors
• Hydrostatic pressure forcing water through foundation walls
• Foundation cracks from settling, soil shift, or temperature changes
• Poor yard grading directing rainwater toward the foundation
• Clogged or absent drainage systems
• Aging or failed waterproofing materials
• Window wells filling with water and leaking inside

Interior waterproofing (French drains, sump pumps, channel drains) captures water after it enters your foundation area and redirects it away before it floods your basement. Faster to install — typically 2–4 days — with no disruption to your yard or landscaping.

Exterior waterproofing (membrane systems, foundation grading) stops water before it ever touches your foundation walls. More comprehensive, requires excavation, but provides the strongest protection — especially in severe cases.

We inspect your specific situation and recommend whichever approach will actually solve your problem most effectively and cost-efficiently. Many homes need both.

A French drain is a perforated pipe buried in a gravel-filled trench that intercepts groundwater and redirects it away from your foundation. On Long Island, where hydrostatic pressure pushes water up through basement floors, French drains are one of our most effective and commonly installed solutions.

We start with a thorough inspection to determine exactly where and how water is entering, then install the system designed for your property. We've completed hundreds of French drain installations across Nassau and Suffolk County. Most jobs are done in 2–4 days with no disruption to your landscaping.

If your basement has a French drain system or any interior drainage, yes — you need a sump pump to remove the water collected by the system. We also strongly recommend a battery backup sump pump for Long Island homes. When a major storm knocks out your power, your sump pump needs to keep running — that's exactly when you need it most.

We assess your specific basement and recommend the right pump type and size for your situation. We've installed hundreds of sump pumps across Long Island.

• Water on the basement floor after rain
• Damp or wet walls in the basement
• White chalky deposits on walls (efflorescence)
• Musty smell or visible mold
• Cracks in foundation walls or floor
• Peeling paint or rust stains on walls
• Sump pump running constantly or failing
• Window wells filling with water
• Bowing or bulging basement walls

Don't wait — water damage compounds over time and small problems become expensive ones. Call 516-920-2543 and we'll take a look at no charge.

Yes — and they should never be dismissed as cosmetic. Cracks form from shifting soil, water pressure, temperature cycles, or structural settling. Left unrepaired, they always get worse and allow water and moisture into your home.

We don't just patch and leave — we identify the root cause of the crack and fix it properly using high-performance polyurethane or epoxy injection. Most repairs are done from inside your basement with no excavation required.

This comes up constantly in our reviews. Our inspections are thorough — we look at the full picture, not just the obvious problem. Multiple customers have told us we found hidden foundation cracks and structural issues that previous contractors missed entirely, in some cases preventing serious long-term damage.

We won't start a project without understanding exactly what's happening with your home first.

• Paver patios, walkways, and driveways
• Front stoops and stairs
• Retaining walls
• Concrete work
• Basement entrances
• Egress windows and wells
• Basement window replacement
• Sill plate replacement

Every masonry project is backed by our comprehensive warranty and done with the same quality we bring to waterproofing — because we know the two go hand in hand on Long Island properties.

Yes — fully licensed and insured throughout Long Island.

• Suffolk County Home Improvement License: HI67081
• Nassau County License: H2216770000
• Town of Freeport License: 19283
• General liability insurance
• Workers' compensation insurance

Yes. Diamond stands behind every job. We've built our reputation on Long Island since 2000 and we intend to keep it — if something isn't right, we come back and make it right. Call 516-920-2543 for specific warranty details on your project type.

We serve all of Nassau County, Suffolk County, and the Town of Freeport. Call 516-920-2543 to confirm coverage for your specific address — we cover all of Long Island.

Yes — 24/7 emergency service, 365 days a year. If your basement is flooding right now, call 516-920-2543 immediately. We respond fast for active flooding and urgent water situations. Don't wait until morning.

Most waterproofing jobs complete in 2–4 days. Exterior membrane work typically takes 1–3 days. Grated channel drains take 2–3 days. Masonry projects vary by scope.

We always give you a specific timeline before any work begins — no surprises, no dragging jobs out.