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TRUSTED BY CORNELIUS, OR HOMEOWNERS

  • Average homeowner rating star icon4.2
    Average homeowner rating
  • Verified reviews icon66
    Verified basement waterproofing services reviews

Verified Reviews for Basement Waterproofing pros in Cornelius, OR

*The Angi rating for Basement Waterproofing companies in Cornelius, OR is a rating based on verified reviews from our community of homeowners who have used these pros to meet their Basement Waterproofing needs.

*The HomeAdvisor rating for Basement Waterproofing companies in Cornelius, OR is a rating based on verified reviews from our community of homeowners who have used these pros to meet their Basement Waterproofing needs.

Last update on August 24, 2025

Find Basement waterproofing pros in Cornelius

Avatar for John's Waterproofing
John's Waterproofing
4.3(
252
)
Foundation, Basement or Crawlspace - Waterproofing / EncapsulationBasement Drainage Channels - InstallBasement Drainage Channels - Repair

Serving Cornelius, OR and surrounding areas

Approved

In business since 1974

Free estimates

Warranties offered

"From the first visit to my home from Sean for an estimate, to the crew that arrived to do the project I was impressed. Everyone was extremely professional. The crew arrived on time, the crew leader introduced me to the rest of the crew and explained how they would proceed with the project. They protected the work spaces with plastic from my garage to the crawl space opening in side my closet. They went to work and kept me informed about the progress. The whole crew worked very efficiently and got the project done in one day. They left work area spotless when they were done. I would highly recommend this company for any waterproofing project!!"
Trim around fireplace was removed and mold found along the base
Fiberglass was drooping away from the home, removing its insulation value
Fiberglass Insulation was falling down in clumps from water weight
This window had been upgraded and given trim to give a clean and finished look
Re removed the below-grade sections of the wall and waterproofed with ThermalDry Radiant vapor barrier and installed a drain system around the interior perimeter

+41

Response time9 hrs
Response rate100%
21 neighbors recently requested a quote
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Avatar for Better Basements and Waterproofing
Better Basements and Waterproofing
5.0(
10
)
Foundation, Basement or Crawlspace - Waterproofing / Encapsulation

Serving Cornelius, OR and surrounding areas

Approved

In business since 2022

Free estimates

Credit card accepted

"Dylan Milroy went in and cleaned out the crawlspace put down plastic and dug a french drain and redirected all the downspouts so that the rain and we had now more water being drained. He is super easy to work honest he follows up to see if you are satisfied with his work.. I recommend him to everyone."
12mil vapor barrier
12mil vapor barrier
Standard Vapor Barrier
Exterior Drainage
Exterior Drainage

+3

3 neighbors recently requested a quote
Recommended by50%of homeowners
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Avatar for Groundworks
Groundworks
4.6(
915
)
Basement Drainage Channels - InstallBasement Drainage Channels - RepairFoundation, Basement or Crawlspace - Waterproofing / Encapsulation

Serving Cornelius, OR and surrounding areas

Approved (Corporate)

In business since 2021

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

Basement
Basement
Basement
Concrete
Concrete

+20

Recommended by93%of homeowners
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Avatar for John's Waterproofing Co.
John's Waterproofing Co.
4.0(
72
)
Foundation, Basement or Crawlspace - Waterproofing / Encapsulation

Serving Cornelius, OR and surrounding areas

Approved

In business since 1974

Free estimates

Warranties offered

"Friends who know what our basement looked like before are flabbergasted. The information they send you after you contact them is super educational and everyone was prompt, polite, and professional. Wish we'd done this sooner."
Encapsulation System
Before Encapsulation
Before Interior Drain System
After Interior Drain System
Finished basement

+38

Response time6 hrs
210 neighbors recently requested a quote
Recommended by93%of homeowners
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Avatar for Pacific Waterproofing & Foundation Solutions, LLC
Pacific Waterproofing & Foundation Solutions, LLC
4.9(
8
)
Foundation, Basement or Crawlspace - Waterproofing / EncapsulationBasement Drainage Channels - InstallBasement Drainage Channels - Repair

Serving Cornelius, OR and surrounding areas

Approved

In business since 2012

Free estimates

Warranties offered

"Very impressed with Darren: his work ethic, thoroughness of the work, cleanliness of the job site when the job was finished. He arrived when he said he would and stopped by when he was done for the day to let me know he was leaving. I certainly would recommend Pacific Waterproofing, LLC."
Response time2 days
6 neighbors recently requested a quote
Recommended by83%of homeowners
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Avatar for Crawlspace Masters, Inc.
Crawlspace Masters, Inc.
4.9(
94
)
Foundation, Basement or Crawlspace - Waterproofing / EncapsulationBasement Drainage Channels - InstallBasement Drainage Channels - Repair

Serving Cornelius, OR and surrounding areas

Approved

In business since 2012

Free estimates

Emergency services offered

"They did a great job adding insulation to my attic. Quick and at a great price."
After
After
After
After
After

+221

Response time2 days
Response rate95%
50 neighbors recently requested a quote
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Avatar for TerraFirma
TerraFirma
4.1(
100
)
Foundation, Basement or Crawlspace - Waterproofing / EncapsulationBasement Drainage Channels - InstallBasement Drainage Channels - Repair

Serving Cornelius, OR and surrounding areas

Approved

In business since 2005

Free estimates

Warranties offered

"The problem ended up being plumbing and not waterproofing. But TerraFirma did a consult right away, diagnosed the issue quickly and was really helpful in figuring out the next steps. I really appreciate their time."
A System Design Specialist helping a homeowner
Encapsulating a crawl space
Fleet of vehicles in our Portland, Oregon locatio
Loading up our truck for a piering job
Loading up a truck for a waterproofing job

+33

Response time10 mins
Response rate100%
105 neighbors recently requested a quote
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Avatar for D & F Plumbing, Heating and Cooling
D & F Plumbing, Heating and Cooling
4.2(
513
)
Basement Drainage Channels - InstallBasement Drainage Channels - Repair

Serving Cornelius, OR and surrounding areas

Approved (Corporate)

In business since 1927

Emergency services offered

Warranties offered

"Just fine, The whole line needs replacing from basement through to street. Will begin work in about a week or so."
Additional Photos
Additional Photos
Additional Photos
Additional Photos
Additional Photos

+18

3 neighbors recently requested a quote
Recommended by79%of homeowners
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Avatar for Legacy Plumbing and Excavation, LLC
Legacy Plumbing and Excavation, LLC
4.5(
76
)
Basement Drainage Channels - Install

Serving Cornelius, OR and surrounding areas

Approved

Super Service Award Winner

In business since 2023

Free estimates

Emergency services offered

"James from Legacy Plumbing and Escavation was professional and friendly did an a awesome job in a timely manner in repairing a leaky shower in a home we had just purchased. Highly reccomend James and Legacy Plumbing and Escavation 🤙"
Sewer Repair
Excavation & Sewer
Response time9 hrs
Response rate95%
774 neighbors recently requested a quote
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Avatar for 3 Mountains Plumbing
3 Mountains Plumbing
4.2(
648
)
Basement Drainage Channels - InstallBasement Drainage Channels - Repair

Serving Cornelius, OR and surrounding areas

Approved

In business since 2000

Emergency services offered

Warranties offered

"Highly recommend! They called when they said they would and showed up when they said they would and finished the project when they said they would. Very friendly and helpful staff all the way around from the dispatchers, Nicole & Michelle, to the Journeymen Tristan and Travis. I have nothing but good things to say about them."
The 3MP Team (Circa 2017)
Bill Kerrigan
Alex Grabbing a Photo
Rolling Through Lake Oswego
Random Patch Photo

+103

Response time1 day
Recommended by92%of homeowners
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Showing 1-10 of 86
Basement Waterproofing questions, answered by experts

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.

If foundation problems are not fixed, they will likely worsen over time, leading to more complex and expensive repairs. Neglecting a damaged foundation can cause a range of issues, including:

  • Structural Damage: Minor problems like small cracks can escalate into major structural issues. This can damage the house above the foundation and, in severe cases, lead to foundation walls caving in or a total collapse.

  • Water Damage and Pests: Moisture and water intrusion can cause flooding, mold growth, and pest infestations.

  • Health and Safety Risks: Mold can lead to poor indoor air quality and other health risks, while structural instability poses a significant safety hazard.

  • Reduced Home Efficiency: A compromised foundation can negatively impact your home's energy efficiency.

To avoid these escalating problems and costs, it's best to hire a foundation repair company to address any issues as soon as you become aware of them. The earlier problems are discovered and fixed, the lower the repair cost will likely be.

In perfect conditions—meaning, no overexposure to the elements without roofing material on top of it—an ice and water shield can last for decades. In fact, many come with a limited lifetime warranty because they should last for a long time. If, however, the membrane is exposed to the elements during building or if there is a delay in installing the roofing material, it might only last up to 180 days if exposed to the elements. The key is to make it a layer of protection and then protect that layer by installing the roofing.

Basements with persistent moisture problems or flooding shouldn’t be finished until the moisture issues have been fixed. In addition, if your foundation is cracked, you have unmitigated radon levels, or you have asbestos or lead pipes, remediate the underlying problem before finishing your basement. Turning a basement into living space before fixing these issues can lead to serious health risks or structural damage. 

A crawl space is an area under the house that provides access to plumbing, electrical, heating ducts, and other HVAC units. Its purpose is to create a buffer between the ground and the living area, helping with ventilation, moisture control, and access for maintenance or repairs. Crawl spaces are most often seen in houses in North America which are built on concrete foundations versus other parts of the world where buildings are constructed differently.

The Cornelius, OR homeowners’ guide to basement waterproofing services

From average costs to expert advice, get all the answers you need to get your job done.

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