914 Basement Waterproofing in Larchmont & Mamaroneck, NY
Larchmont and Mamaroneck are old and flood-conscious: the typical Larchmont home was built around 1940 (90% before 1980) and the typical Mamaroneck village home around 1953. Mamaroneck publishes its own flood-preparedness handbook. Homes on hillsides, near brooks and rivers, and along the Long Island Sound shore can see very different water patterns, so the right fix depends on where the water comes from. For a house with finished space or valuable contents, ask each company to show you the source of the water and to explain what happens in a power outage.
Waterproofing companies for Larchmont & Mamaroneck
How we pick: we list up to six companies per page. Independent firms come first, then firms based outside Westchester, then franchise or network affiliates. Companies that name the town as served come before those that serve the whole county. Listings are free, not paid, and not an endorsement. Home improvement license status was looked up in the Westchester County consumer license search on Oct 26 to 27, 2026, plumber license status in the county trade license search on Oct 27, 2026, and NYS mold license status in the state Labor Department data set; each profile shows what we found.
Avellino Construction
No rating collected yetBasement, foundation, chimney and exterior-wall waterproofing; masonry and roofing; 24-hour emergency service
De La Paz Masonry
No rating collected yetWaterproofing, French drains, sump pumps, masonry
F. La Rocca & Sons
No rating collected yetMasonry, drainage and waterproofing
Kellets Anchored Home Improvement
No rating collected yetExterior and interior waterproofing, drainage, crack repair, sump systems, foundation repair coordination
Naclerio Construction LLC
No rating collected yetBasement waterproofing, drainage, masonry and foundation work
Sundahl Waterproofing
No rating collected yetInterior and exterior waterproofing, drainage, sump pumps, foundation repair
Housing in Larchmont & Mamaroneck
| Place | Typical year built | Built before 1950 | Built before 1980 | Median home value |
|---|---|---|---|---|
| Larchmont | 1940 | 63.5% | 89.7% | $1,635,500 |
| Mamaroneck | 1953 | 44.2% | 78.4% | $717,200 |
Source: U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates (tables B25035, B25034, B25077), retrieved Oct 2026. Estimates carry a margin of error.
Flooding and water in Larchmont & Mamaroneck
- Westchester County’s Long Island Sound watershed program lists this municipality in the watershed study areas for “Blind, Beaver Swamp and Brentwood Brooks; Milton and Port Chester Harbors”, “Mamaroneck and Sheldrake Rivers; Mamaroneck Harbor”, “Pine and Stephenson Brooks; Larchmont Harbor”. [source]
- The Village of Mamaroneck describes itself as especially prone to flooding, sitting at the junction of the Mamaroneck River, the Sheldrake River, Beaver Swamp Brook, three watersheds, a 250-acre underground aquifer and Long Island Sound. [source]
- The state’s Mamaroneck River study found repeat flooding driven by undersized bridges and channels and tight development along the banks. [source]
- In Ida (September 2021), news reports described up to 14 feet of water in some Mamaroneck neighborhoods and basements filling to the first floor. [source]
Permit notes for Larchmont & Mamaroneck
From the municipality’s own pages, retrieved Oct 2026. Rules change, so call the building department before work starts.
- Larchmont: new sump pumps and drainage facilities need village permits; discharge should go to an owner-maintained dry well or detention basin. Discharging onto sidewalks or streets is not permitted and sump pumps may not connect to the sanitary sewer. [source]
- Mamaroneck: Local Law 2-2024 requires a plumber’s certification, by a plumber licensed to do business in Westchester County, covering sump pump discharge and sanitary sewer laterals. [source]
What it costs
A modeled estimate for White Plains puts a typical interior drain system for about 120 linear feet of wall near $7,100, with most bids between roughly $3,000 and $12,200 (RenoVetted). Exterior drainage is modeled at $4,600 to $18,200 and full exterior waterproofing at $5,700 to $22,800 for the same 120 feet. These are modeled figures, not Westchester bid data, and larger or harder-to-access homes can cost more. We did not find any Westchester contractor price lists. Full cost guide with sources.
Frequently asked questions
How many waterproofing companies serve Larchmont & Mamaroneck?
We show 6 of 13 companies we found for Larchmont & Mamaroneck: 10 name Larchmont & Mamaroneck as an area they serve, and the rest serve all of Westchester County. Always confirm a company covers your address.
Does Larchmont & Mamaroneck require a permit for this work?
Often yes. See the permit notes on this page, then call the Larchmont & Mamaroneck building department before you sign a contract.
Is interior or exterior waterproofing better?
Exterior work stops water at the wall face but means digging out the foundation, which is disruptive and costs more, especially around mature landscaping. Interior drainage systems collect water that gets through and send it to a sump pump. Ask each company to explain why it recommends one approach for your house.
Will a sealer paint fix my wet basement?
Coatings can help with minor dampness, but they rarely stop water under pressure from saturated soil. If you see water at the floor-wall joint or through cracks, get a drainage assessment first.
Nearby
Sources
- Westchester County Planning: Long Island Sound Watershed Program (watershed study areas by municipality)
- Village of Mamaroneck Building Department: Flood Preparedness Handbook
- NYS DEC / Village of Mamaroneck: Mamaroneck River Flood & Resiliency Study Report (2023)
- ABC7 New York: Ida damage, 14 feet of water in Mamaroneck (Sept. 2, 2021)
- Village of Larchmont Building Department: Sump Pumps
- Village of Mamaroneck: Local Law 2-2024 (plumber’s certification for sanitary sewer laterals)
- U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates, tables B25034, B25035, B25077 (via Census Reporter)
Get up to 3 quotes in Larchmont & Mamaroneck
Tell us about your project and we'll connect you with local pros. Free, no obligation.
Start my free quote request