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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 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

164 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
7 neighbors recently requested a quote
Recommended by100%of homeowners
Avatar for The Builders & Cleaners
The Builders & Cleaners
4.9(
122
)
Basement Drainage Channels - InstallBasement Drainage Channels - Repair

Serving Cos Cob, CT and surrounding areas

Approved

In business since 2018

Free estimates

Emergency services offered

Based in West Haven, Connecticut, our team has provided an excellent, affordable service to more than thousands of houses over the years. We are committed to supporting our customers throughout the evaluation process, during the service itself and are available to answer any queries once the work is complete. \nWe are a licensed and fully insured company aiming to respond to all requests involving our services within 24 hours or less. Our professional and knowledgeable staff have a combined experience of over 12 years within the construction, air duct cleaning, and landscaping industries, ensuring guaranteed satisfaction with every job. \nWe pride ourselves in providing a safe, hazard-free environment and maintaining respectful, cordial communications with all of our clients. All technicians can be relied on to keep project sites clean both during and after the work is complete. \n

Dust out from the ductwork
Dust out from the ductwork
Clean vent
Clean vent
Dust in the return

+1839

Response time1 day
Response rate92%
Recommended by85%of homeowners
Avatar for Ron's Masonry
Ron's Masonry
5.0(
30
)
Basement Drainage Channels - InstallFoundation, Basement or Crawlspace - Waterproofing / Encapsulation

Serving Cos Cob, CT and surrounding areas

Approved

In business since 1995

Emergency services offered

Small jobs welcome

At Ron's Masonry, we pride our company on reliability, great communication, integrity and quality work. We strongly believe in giving our absolute best in all of our projects no matter how big or small. We are experts in our trade and will always keep you educated on your particular task or project. We look forward to earning your business.

Walkway
Steps
Footing
Walk
Walk

+36

Response time1 day
Response rate86%
27 neighbors recently requested a quote
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

396 neighbors recently requested a quote
Avatar for Aldos plumbing
Aldos plumbing
5.0(
35
)
Basement Drainage Channels - Install

Serving Cos Cob, CT and surrounding areas

Approved

Free estimates

Emergency services offered

Small jobs welcome

At Aldo's Plumbing, serving the Tri-State Area, we prioritize customer satisfaction. Our expertise in water heaters ensures that your home projects are handled with care. Contact us today for a seamless experience!

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+41

1 neighbors recently requested a quote
Recommended by44%of homeowners
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

We pride our company on reliability, great communication, integrity, and quality work. We are experts in our trade and will do our best to keep you as educated as we can on your particular task or project. We look forward to earning your business!

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

AA Outdoor Services, LLC is a third-generation contractor proudly serving homeowners and businesses throughout Connecticut. We specialize in drainage solutions, French drains, foundation drainage systems, yard drainage, retaining walls, excavation, concrete, asphalt, and site development services.\n\nOur team is committed to delivering high-quality workmanship, reliable service, and long-lasting solutions that protect and improve your property. Whether you are dealing with standing water, foundation water intrusion, poor drainage, or outdoor construction needs, we provide customized solutions designed to meet your specific goals and budget.\n\nWith years of hands-on experience and a reputation built on integrity, professionalism, and customer satisfaction, AA Outdoor Services, LLC is dedicated to getting the job done right the first time. We proudly offer free estimates and stand behind our work with industry-leading warranties.

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

In most climates, contractors recommend closing your crawl space vents in winter. Keeping them shut protects your crawl space from freezing temperatures, pests, and cool breezes that can lead to chilly floors in your home. However, it's often best to speak with a local crawl space team about your specific design and its relationship to the winter season.

Yes, you can technically make a crawl space liveable, but the only way to do so is by converting it into a basement. While some crawl spaces are big enough to walk through and store large items, they lack appropriate insulation and space to be liveable.

One handy thing about whole-house dehumidifiers is, once installed, you don’t have to worry about placement or changing the dehumidifier’s position. But if you are using a portable dehumidifier, we suggest keeping it away from walls, vents, and furniture. It needs a central, unobstructed spot with access to lots of air to do its job.

Covering the dirt floor in your crawl space with a vapor barrier helps insulate the space and improve the air quality in your home. It protects your crawl space from pest infestations, excess moisture, and mold growth. It also makes the crawl space less dusty, which means there’s a lower chance of dust mites breeding and causing allergic reactions in your home.

Roughing in and connecting utilities are the hardest parts of finishing a basement, and they’re the parts we typically don’t recommend doing as a DIY project. Unfortunately, your finishing timeline can be extended by weeks while you wait for contractors and inspectors to install electrical wiring, plumbing lines, and heating/cooling equipment and carry out inspections.

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.