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Best basement waterproofing pros near Cos Cob, CT

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TRUSTED BY COS COB, CT HOMEOWNERS

  • 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
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Additional Photos

+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

486 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

A plastic vapor barrier should completely cover your basement to prevent water from penetrating through the walls. This typically goes before installing insulation to prevent moisture from building up and becoming trapped on the inside of your insulation, where it can collect and lead to mold damage. Installing insulation after the vapor barrier allows for any moisture to exit the walls for better ventilation.

Egress windows or doors are required in finished basements to meet safety and building codes. If your basement is unfinished and used as a storage space, egress windows are not required, but anything considered a habitable space must have an additional point of egress in addition to the stairs.

Yes, it is possible to over-dehumidify a house by removing too much moisture from the air. This can create an overly dry environment that negatively affects those with respiratory or skin issues, and may cause your skin, hair, and sinuses to feel dry. However, this is unlikely to happen with most modern dehumidifiers, as they are equipped with moisture sensors and adjustable settings. These features allow the unit to pause automatically when the desired humidity level is reached, preventing the air from becoming uncomfortably dry. In contrast, older or more basic dehumidifiers left running for too long could potentially over-dry the air. To avoid this, aim for a balance between removing excess moisture and maintaining a comfortable environment. You can often monitor your home's humidity levels using a modern thermostat for guidance.

Several factors can impact the cost of waterproofing your basement. Some of the most common cost factors include:

  • Location

  • Square footage

  • Cause of the water leak

  • Type of foundation

  • Accessibility

  • Waterproofing method

  • Materials

  • Contractor experience and availability

  • Engineering reports, if needed

  • Structural and other repairs

  • Permits

Pooling or standing water in your basement should be cause for alarm and action. This indicates that there is a leak or a drainage issue, and until you repair the root of the problem, the situation will only happen again or grow in severity. It’s important to deal with water damage as soon as it occurs.

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.