Top-rated basement waterproofing pros.

Best basement waterproofing pros near Diamond Bar, CA

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Top-Rated Basement waterproofing pros in Diamond Bar - Updated Nov 2026

Avatar for Alpha Structural, Inc.
Alpha Structural, Inc.
4.6(
241
)
Foundation, Basement or Crawlspace - Waterproofing / EncapsulationBasement Drainage Channels - InstallBasement Drainage Channels - Repair

Serving Diamond Bar, CA and surrounding areas

Approved (Corporate)

In business since 1992

Free estimates

Emergency services offered

"Erinn was my initial contact and he gave a very through and fair estimate. We had structural work done to support floor joists and large beams under the garage that needed replacing. Ernesto and his team, Julio, Salvatore and Gilder worked tirelessly to complete the work and were respectful, punctual, informative and good humoured throughout the entire process. I would not hesitate to use them again or recommend them to others. A really great company!!"
Basement Addition
Basement Expansion
Caisson Supported Retaining Wall
Cantilevered Deck Design Build
Deck Expansion and Slope Failure with Retaining Wall

+323

Response time10 hrs
Response rate100%
11 neighbors recently requested a quote
Avatar for Groundworks
Groundworks
3.5(
176
)
Foundation, Basement or Crawlspace - Waterproofing / EncapsulationBasement Drainage Channels - InstallBasement Drainage Channels - Repair

Serving Diamond Bar, CA and surrounding areas

Approved (Corporate)

In business since 1995

Free estimates

Warranties offered

"Roger and his crew of Manuel, Carlos and Josias did everything we asked for and more. Roger answered all of our questions, kept us informed on the status of the project and managed the project extremely well. We definitely made the right decision having Groundworks do our project."
Foundation
Foundation
Foundation
Concrete
Concrete

+16

Response time11 hrs
95 neighbors recently requested a quote
Recommended by38%of homeowners
RSF Construction Inc.
1.0(
1
)
Basement Drainage Channels - InstallBasement Drainage Channels - RepairFoundation, Basement or Crawlspace - Waterproofing / Encapsulation

Serving Diamond Bar, CA and surrounding areas

Approved

In business since 2019

Free estimates

Credit card accepted

RSF Construction Inc. is a leader in providing our customers with the highest quality service in an honest, efficient, and professional way. Our pledge is to create successful relationships with our customers, employees and community by building trust, treating every project with the utmost integrity and exceeding expectations. We look forward to working with you!

Palm Construction, Inc.
5.0(
112
)
Foundation, Basement or Crawlspace - Waterproofing / Encapsulation

Serving Diamond Bar, CA and surrounding areas

In business since 2016

Free estimates

Credit card accepted

It can be a daunting task looking for not only the right contractor for your job but also the right contractor for you. We completely understand what you're going through. We know every customer has different desires, different needs and different schedules. We're not only here to turn your ideas into reality but to make it a memorable experience every step of the way. Call us right now, no matter where you are in the planning process.

Recommended by100%of homeowners
Palm Construction, Inc.
5.0(
90
)
Foundation, Basement or Crawlspace - Waterproofing / Encapsulation

Serving Diamond Bar, CA and surrounding areas

In business since 2016

Free estimates

Credit card accepted

"We worked with Ali (sales manager) and Tony (project manager), who took the time to design a project that made sense for our property and our budget, made a number of suggestions and recommendations and were never pushy or tried to "sell" us on something. The crew really went above and beyond to provide top quality workmanship and overall we were in very good hands. Highly recommended!"
Recommended by100%of homeowners
Avatar for Monarch Concrete Coatings
Monarch Concrete Coatings
4.8(
17
)
Basement Drainage Channels - InstallBasement Drainage Channels - RepairFoundation, Basement or Crawlspace - Waterproofing / Encapsulation

Serving Diamond Bar, CA and surrounding areas

In business since 1985

Free estimates

Credit card accepted

"We had a second story deck that was leaking water into the garage. We got 4 companies to come and give us a quote.  Two of them were cheaper but they seemed as puzzled as we were about what to do and could not guarantee from future problems. The other company suggested rebuilding the entire deck and was way out of budget. Ryan from Monarch Custom Coatings came with a sample that had several layers to waterproof the deck - we were very impressed that he was very knowledgeable and has a lot of experience with this type of work. He and his crew worked very hard, always professional, prompt, courteous, and our deck looks amazing now. We were so happy with them that we hired them again to redo the garage floors. We have had bad experiences in the past with contractors, so we know that finding a good, reliable, and honest one is very hard and rare. We highly recommend Monarch Custom Coatings!"
Additional Photos
Additional Photos
Additional Photos
Additional Photos
Additional Photos

+19

Recommended by93%of homeowners
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Basement Waterproofing FAQs, answered by experts

Proper basement ventilation is very effective at reducing humidity. Without enough ventilation, your basement is prone to mold and moisture damage. Your basement should have as much natural ventilation via windows and doors as possible, and if your budget allows, you should also consider installing an ERV system to keep basement humidity levels at bay.

If not properly maintained, an underground downspout may damage your home's foundation. A clogged downspout can back up, causing water to pool around the base of your home and seep into the foundation. Regular inspections and maintenance keep your downspout in good working order, preventing damage and protecting your home.

Periodic inspections and addressing drainage issues prevent further damage.

The purpose of crawl space encapsulation is to prevent mold by blocking moisture and reducing humidity. If the vapor barrier is properly installed, it significantly reduces the chance of mold developing within the crawl space. However, mold can sometimes grow behind the encapsulation material, but it will be sealed away from the main area. Additionally, moisture can still condense inside the encapsulated space, so if you notice excess humidity, installing a dehumidifier is recommended to prevent mold and mildew growth.

Ideal humidity conditions generally range from 30% to 50%, with 45% considered optimal humidity for most homes. If your humidity levels drop below that range, you can turn your dehumidifier off. Additionally, suppose the temperature where the dehumidifier is installed falls below 60 degrees Fahrenheit. In that case, it's best to turn it off and unplug it since cooler temperatures can cause the unit's coils to freeze.

The Diamond Bar, CA homeowners’ guide to basement waterproofing services

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