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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

430 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

Brick is designed to absorb moisture, but it is also designed to let it evaporate as well. So in general, the goal shouldn’t necessarily be keeping moisture out but making sure it has the room to breathe. If you have excess moisture getting through your brick wall, it’s more likely that you have a crack or other issue at play that a typical sealant won’t fix. So, instead of investing in sealant, try repairing your brick wall instead.

Most people consider a French drain to be one of the most effective solutions for foundation leaks, but it’s not always a standalone solution. French drains will help keep water away from your foundation to reduce the risk of leaking and structural damage from soil expansion, but depending on your foundation type and location, you might need other systems or techniques—like soil gradation and gutter and leader installation—to resolve the underlying problem.

Yes, the air from a damp basement can travel up into your living area through a process called the stack effect, so moisture, mold spores, and other debris in your basement air can all decrease your indoor air quality on your main floors. Additionally, damp basements can promote the rotting of building materials, which can damage flooring, insulation, and framing on your first floor in addition to materials in the basement.

The best type of basement ventilation system depends on your budget, the moisture in your basement’s air, and the types of windows you have down there. You should consider all of these factors when choosing a ventilation system. However, the most effective method for basement ventilation is an energy recovery ventilator (ERV) or a whole-house ventilation system, which preheats or precools incoming air from the outside while also managing water vapor.

Walkout basements cost more than other kinds of basements, and can also increase your risk of leaks as well as a loss of insulation, leading to higher heating and cooling costs. Improperly installed walkout basements may lead to structural issues with your foundation, so ensure you’re working with a contractor who has extensive experience with this kind of basement.

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.