Basement Finishing & Waterproofing in Staten Island A dry basement, finished as far as the flood maps allow
Staten Island basements run from pre-1960 North Shore foundations to South Shore houses with a shared wall and a flood map to answer to. We waterproof first, then finish what the rules let the space become.
- English and Russian spoken
- Licensed & insured
- 24/7 emergency service
- Free estimates
- Financing options available
Local know-how
Basement Finishing & Waterproofing in Staten Island homes
Staten Island basements differ by shore. In the Census Bureau’s 2020–2024 estimates, 59 to 62 percent of housing units in the North Shore ZIPs 10301, 10302 and 10310 were built before 1960, while Tottenville’s 10307 has a median build year of 1990. On the South Shore, attached one-family houses make up 38.2 percent of units in 10308 and 35.5 percent in 10309, so many basements share a wall with the house next door.
The water differs too. The city’s 2013 resiliency report found the post-Sandy floodplain reaching residential blocks from Midland Beach to Tottenville, and a 2024 Federal Reserve Bank of New York study placed the East Coast of Staten Island among the areas with the highest flood risk to basement housing. Groundwater is harder to read: THE CITY reported in 2023 that Staten Island has not had the consistent monitoring Brooklyn and Queens once had.
Common problems in Staten Island
Finishing inside the flood zone
In a special flood hazard area, the Department of Buildings counts the cost of work toward the substantial improvement test. At 50 percent or more of the house’s market value, Appendix G applies, which for a home means elevating living space and filling in the basement or cellar.
Basement units and the new flood maps
The Department of Buildings ADU rule, in effect from October 2025, bars a basement or cellar unit where the lot is in the special flood hazard area, DEP’s 10-year rainfall flood risk area or the coastal flood risk area. On flood-mapped East and South Shore blocks, a basement rental is off the table before design starts.
Party walls on South Shore houses
More than a third of the units in 10308, 10309 and 10312 are attached houses. A shared wall usually cannot be dug out and sealed from outside, so water there is managed from inside, with drainage to a sump and a vapor-controlled finish.
Older North Shore foundations
Around St. George, Port Richmond and West Brighton, roughly six in ten housing units were built before 1960. Foundations that old get a full look for cracks, porous joints and old patches before any framing goes up.
Where we see it
- Great Kills Attached houses whose basements share a wall, near the harbor.
- Midland Beach and New Dorp Beach Floodplain basements where finishing and rental limits apply.
- Tottenville Newer houses, with the floodplain running up the creeks.
- St. George and Tompkinsville The Island’s oldest foundations.
- Todt Hill and Lighthouse Hill Sloped lots on the mid-Island ridge, where rain runs toward the house from uphill.
How a call works in Staten Island
Checking the maps first
Before we price a finished basement, we look up the lot on the city’s flood and rainfall maps, because that decides what the space can legally become.
Working beside a neighbour’s wall
On an attached house the waterproofing, drainage and framing happen from your side of the party wall, and we plan access so the work stays inside your property.
Estimates are free, and emergencies are answered 24/7.
What is included
The work itself is the same in every borough. See everything our basement finishing & waterproofing service covers.
Basement Finishing & Waterproofing questions from Staten Island
Can I turn my Staten Island basement into a rental unit?
Only if the lot is outside the special flood hazard area, DEP’s 10-year rainfall flood risk area and the coastal flood risk area, and the space meets the rest of the ADU rule. We check the maps before anything is designed.
Does finishing a flood-zone basement count toward the 50 percent rule?
Yes. The Department of Buildings counts the cost of the work, even permit-exempt work, toward the substantial improvement test, so a large finish can trigger Appendix G for the whole house.
My block has never flooded. Do I still need waterproofing?
Perhaps not a full system, but DEP’s Rainfall Ready guide still advises sealing foundation cracks and sending roof water away from the foundation walls, both worth doing before drywall hides them.
Is a backwater valve part of basement waterproofing?
It handles a different water: sewer water pushing back through basement toilets, sinks and drains. DEP suggests asking a plumber whether one makes sense, and a finished basement is the place where it matters most.
Free estimate
Get a free estimate in Staten Island
Ready to turn a damp basement into real living space? Begin with a free estimate.