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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 Connecticut Basement Systems, Inc.
Connecticut Basement Systems, Inc.
4.3(
589
)
Foundation, Basement or Crawlspace - Waterproofing / EncapsulationBasement Drainage Channels - InstallBasement Drainage Channels - Repair

Serving Cos Cob, CT and surrounding areas

Approved

In business since 1987

Free estimates

Warranties offered

"Great results from waterproofing. Turned my spring flooding anxiety to calm. As humidity rose in summer, I put in a small dehumidifier. Made basement noisy as it struggled to dry and produced a lot of heat. As temperatures rose to about 83 down there and the humidity rose to over 68%, I had same people put in a whole basement commercial-grade dehumidifier. The small unit dropped the humidity to around 50% in less than an hour. Incredible performance and have me peace of mind and peace and quiet downstairs. Temperature dropped gas as well. Weel worth the price to save my most expensive investment."
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+12

176 neighbors recently requested a quote
Recommended by90%of homeowners
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."
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+24

Response time7 hrs
6 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

490 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
3 neighbors recently requested a quote
Recommended by100%of homeowners
Avatar for KNL CONSTRUCTOR LLC
KNL CONSTRUCTOR LLC
5.0(
11
)
Basement Drainage Channels - Install

Serving Cos Cob, CT and surrounding areas

Approved

In business since 2020

Free estimates

Credit card accepted

*****Call Today for an Estimate @ 475-279-4864***** With over 10 years of experience, I take pride in my quality craftsmanship. We are owner operated, and believe in building long-term relationships with our clients by delivering honesty along with exceptional work. We pride our company on reliability, great communication, integrity, and customer service. We are experts in our trade and will do our best to keep you as educated as we can on your particular project. Give us a call today! We look forward to working with you!

Pavers
Pavers
Concrete Border
Concrete Border
Bluestone

+2

24 neighbors recently requested a quote
Recommended by66%of homeowners
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Basement Waterproofing FAQs, answered by experts

Some basement waterproofing methods can actually cause your water or moisture problems to get worse, which is why it’s so important to call in a professional who knows how to solve your underlying issue and use the appropriate waterproofing methods. An example of this would be applying latex waterproofing paint to the insides of your basement walls without fixing the water issue outside. Doing so can trap moisture in the basement walls, which can promote mold growth, peeling paint, and even damaged concrete. However, when done by a professional, the only downside to basement waterproofing is the up-front cost.

Due to the nature of basements, some level of waterproofing is necessary to prevent water from seeping in and causing damage. Some definitive signs that your basement needs waterproofing measures or needs existing waterproofing measures need to be updated include:

  • Water in your basement, including damp walls or puddles on the floor

  • Mold spots in your basement

  • Musty smells or odors

  • Warped doors or walls

  • Cracks in walls

  • Insect issues, such as cockroaches and termites

The best way to ensure the ground next to your home’s foundation drains properly is to divert water away from it as much as possible. While a flood wall can stop water from entering the house, gutters and spouts can help direct rainwater and melting snow away from the foundation. Keep your gutters as clear as possible from dead leaves and other yard debris so they can effectively divert water from your house. Add extenders to the spouts so the water runs out and away from your home, not into the surrounding soil.

If you set up a dehumidifier, it will usually dry out your wet crawl space within 12 to 24 hours. Once the space is dry, it’s a good idea to take preventative measures to keep it dry. These include installing a French drain or other exterior foundation drainage system, installing a sump pump in the crawl space, and installing a vapor barrier in addition to leaving the dehumidifier running.

Below-ground shelters are the best in terms of durability, but there is a risk of flooding and obstruction. Modern technology and rigorous construction requirements make above-ground shelters a better option for accessibility, safety, and, usually, your budget. They may not have the same aesthetic appeal, but many of their features make above-ground shelters a better option. 

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.