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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

"We just had American Dry Basement install a waterproofing system in our basement. We've had issues with water in our basement and needed a total solution so we can sleep at night and go away without worrying about flooding. Steve T from American Dry came to our house and presented us with what the solution will look like and thoroughly explained the entire process. He also answered all our questions and was always available to talk to. He is extremely knowledgeable and an excellent professional to work with. Then Wilson and his two-man crew came to do the work and they were all professional, extremely hard working and respectful of our home. They always started early and worked all day long to get the job completed. They wrapped up all items that were still exposed after we cleaned out most of our basement, used vacuums and filters to minimize all the dust and left our basement cleaner than it was before. We highly recommend American Dry Basement Systems and we're so happy we chose them over the others we received estimates from. And their price was more than competitive for what we believe is a much better solution."
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
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

475 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

Yes, you can add a bathroom to an unfinished basement, but you’ll want to take proper precautions if doing so. As with any bathroom addition, you’ll need to make sure that it’s approved by local building authorities first. With unfinished basements, you especially need to keep an eye on proper ventilation practices.

Yes, water and water vapor can seep through cracks in your basement floor, which means you should address all basement floor cracks, even if they don’t indicate structural issues. Sealing settling cracks and shrinkage cracks is a good idea to keep water and moisture outside where it belongs. Doing so can improve your indoor air quality, reduce the risk of mold growth, make your home more comfortable, and help prevent pest infestation.

Yes, basement insulation needs a vapor barrier due to its susceptibility to moisture seeping in from the outside of the house. You should install a moisture barrier before you install insulation or purchase insulation that comes prebuilt with a moisture barrier to avoid water damage in your insulation and costly mold and water remediation expenses. 

You should plan on waiting at least a year and ideally two to three years after construction before finishing your basement. This will give the foundation time to settle in response to the weight of your home and the expansion of the surrounding soil. You can then repair your foundation and seal any cracks as needed before finishing it to reduce your risk of future leaks or other issues.

Preventing future basement flooding often involves installing sump pumps, improving drainage, sealing foundation cracks, and maintaining gutters. Costs vary, but preventive measures can range from a few hundred to several thousand dollars, depending on the solutions chosen. Investing in prevention can save you money on future flooded basement cleanup costs and repairs.

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.