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Best basement waterproofing pros near Cos Cob, CT

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  • Average homeowner rating star icon4.7
    Average homeowner rating
  • Verified reviews icon46
    Verified basement waterproofing services reviews

Top-Rated Basement waterproofing pros in Cos Cob - Updated Nov 2026

Avatar for American Dry Basement Systems, LLC
American Dry Basement Systems, LLC
4.9(
118
)
Foundation, Basement or Crawlspace - Waterproofing / Encapsulation

Serving Cos Cob, CT and surrounding areas

Approved

In business since 1997

Free estimates

Credit card accepted

"I had my basement waterproofed almost 3 years ago by them and I had no issues since then with the basement flooding regardless of how much it rains. I highly recommend using American Dry Basement!"
Drainage Trench
Jackhammer
Mixing SuperCrete
Compress Wash Stones
Spreading SuperCrete

+7

Response time11 hrs
3 neighbors recently requested a quote
Recommended by66%of homeowners
Avatar for Dirty Deeds Basement Waterproofing
Dirty Deeds Basement Waterproofing
5.0(
4
)
Foundation, Basement or Crawlspace - Waterproofing / EncapsulationBasement Drainage Channels - InstallBasement Drainage Channels - Repair

Serving Cos Cob, CT and surrounding areas

Approved

In business since 2012

Free estimates

Emergency services offered

"Dean and his crew were professional, reliable, extremely neat/clean and went above and beyond, often, to make the sure work was completed to my satisfaction. They did small things not even required to make sure the entire basement area was much more than even expected. The basement has never been so dry in the 40 years I have lived here. I would hire them again in a heartbeat."
Additional Photos
Additional Photos
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Additional Photos
Additional Photos

+24

Response time7 hrs
7 neighbors recently requested a quote
Recommended by100%of homeowners
Avatar for Groundworks
Groundworks
4.9(
13
)
Foundation, Basement or Crawlspace - Waterproofing / EncapsulationBasement Drainage Channels - InstallBasement Drainage Channels - Repair

Serving Cos Cob, CT and surrounding areas

Approved (Corporate)

Super Service Award Winner

In business since 2025

Free estimates

Warranties offered

Groundworks is the North America's leading and fastest-growing foundation repair and water management solutions provider. Groundworks is a vertically integrated company with its own manufacturing operations and a world-class software solution, allowing us to serve our customers more effectively. From the first phone call to the annual maintenance offered, our customers have peace of mind knowing we're there with one mission to repair, protect and improve their home. For state licenses visit Groundworks.com/licensing

Foundation
Foundation
Foundation
Concrete
Concrete

+16

385 neighbors recently requested a quote
Avatar for AG Property Maintenance, LLC
AG Property Maintenance, LLC
4.6(
12
)
Foundation, Basement or Crawlspace - Waterproofing / Encapsulation

Serving Cos Cob, CT and surrounding areas

Approved

In business since 2012

Free estimates

Offers commercial services

"Pedro and team solved an ongoing pond drainage issue that was able to be resolved. Many companies came and charged us money for half a job and this was not the case with AG. They were professional, proficient and quickly got to the source of the problem in one day. Prices were fair and they did not have to come back as they had all the supplies they needed to start and finish the job which is very rare for a major culvert issue like this one."
Brookfield ct
Brookfield ct
Brookfield ct
Brookfield ct
Brookfield ct

+4

Response time2 days
4 neighbors recently requested a quote
Recommended by100%of homeowners
Avatar for AA Outdoor Services, LLC
AA Outdoor Services, LLC
3.9(
33
)
Foundation, Basement or Crawlspace - Waterproofing / Encapsulation

Serving Cos Cob, CT and surrounding areas

Approved

In business since 1990

Free estimates

Small jobs welcome

"Vincent did an absolutely beautiful job on my cement and asphalt driveway. Their craftsmanship was top-notch. They finished the job quickly, and left the work area clean when they were not there. They stayed in touch throughout the process, and they take tremendous pride in their work. I have worked with hundreds of contractors over the years and these folks are among the very best and most reliable. Cannot say enough good things, also the prices were competitive, and they delivered a better quality of work than I would expect for a similar price."
Driveway in New Haven (West Haven)
Rear entrance and parking area (West Haven)
Rear entrance and parking area (West Haven)
Step repair (West Haven)
Step repair (West Haven)

+61

Response time9 hrs
Recommended by100%of homeowners
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Basement Waterproofing FAQs, answered by experts

The best basement waterproofing method depends on the specific issue causing the water intrusion. For minor problems, simple solutions like installing a properly functioning gutter system to direct runoff away and grading the soil to slope away from your foundation can be effective.

If you have more significant water problems, the solution will need to be more robust:

  • For standing water on the basement floor, a floor drain or a sump pump system may be the best solution.

  • For water pooling around the foundation, installing an exterior French drain can intercept water before it reaches the basement walls.

Other effective waterproofing methods, which can be used depending on your home's specific needs, climate, and soil type, include sealing the interior walls, landscape alteration, installing interior drainage systems, and using a dehumidification system to control moisture levels.

You’ll need to reseal the foundation every five to 10 years, depending on the sealant you’ve used, the moisture conditions present in and around your home, and the condition of your foundation. Having a foundation inspection conducted before reapplication can help you catch any problems before you begin resealing. Of course, if you notice any new leaks or other moisture problems at any time, it may be necessary to reseal the foundation sooner.

Although the two terms are closely related and often used interchangeably, pier and beam foundations and crawl spaces are different things. A pier and beam foundation is made up of concrete piers and wooden beams and creates a space under the home known as a crawl space. There are several types of foundations that create crawl spaces, often collectively known as “crawl space foundations,” but the crawl space itself is separate from the foundation. 

Methods include interior sealants, exterior excavation and waterproofing membranes, sump pump installation, and vapor barriers for encapsulation. Techniques vary based on the structure and severity of moisture issues.

Mold growth is just one common sign of excess moisture in the bathroom. You may also see the paint in the room start to peel away from the walls, or that the walls remain wet for some time after you bathe.

Condensation on the windows is another sign that your bathroom has a potential moisture problem. The room itself may start to smell like mildew.

The Cos Cob, CT homeowners’ guide to basement waterproofing services

From average costs to expert advice, get all the answers you need to get your job done.