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Top-Rated Radon detection and reduction specialists in O Fallon - Updated Nov 2026

Avatar for Quacker's Waterproofing & Basement Repair, LLC
Quacker's Waterproofing & Basement Repair, LLC
4.7(
167
)
Radon Gas - AbatementRadon Gas - Testing

Serving O Fallon, MO and surrounding areas

Approved

In business since 2001

Free estimates

Warranties offered

"Quacker's Waterproofing was wonderful. When they came for the estimate, they were fast and no nonsense. They weren't trying to convince me of things that needed doing or dramatizing the work for more money. When I had questions about the work, they didn't make me feel dumb but took extra time out of their day so that I had peace of mind with my foundation. I hope to never need their help again, but I will definitely call them if I do. Special kudos to Rob!"
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+1

5 neighbors recently requested a quote
Recommended by97%of homeowners
Avatar for D and S Home Inspections
D and S Home Inspections
5.0(
9
)
Radon Gas - Testing

Serving O Fallon, MO and surrounding areas

In business since 2017

Free estimates

Credit card accepted

"Scott was on time. He is a very personal person. Shows you different items he finds during his inspection. His Technology is above par, great part is he doesn't charge extra for this."
No so handy handy man repair
ASHI
InterNACHI BUY BACK
Response time2 hrs
Recommended by100%of homeowners
Avatar for Scope Environmental
Scope Environmental
5.0(
15
)
Radon Gas - Testing

Serving O Fallon, MO and surrounding areas

In business since 2023

Free estimates

Small jobs welcome

"I used Scope Environmental recently to test floor tile and the underlying mastic to determine if either contained asbestos. I selected Scope because Jeff was very responsive, professional, independent of the abatement companies and his price was competitive. Jeff suggested testing both the tiles and mastic. The tiles tested positive for asbestos but the mastic contained no asbestos. As a result, I saved considerable expense by abating the tiles only and not the mastic so I also used Scope again for the post abatement air testing rather than the abatement company. I would hire Scope again for material and air testing for asbestos, mold or any other potentially toxic materials."
Black mold inside closet
Mold growth in HVAC Closet
Asbestos Flooring
Floor sample collection
Asbestos Adhesive

+10

Response time4 hrs
Response rate96%
Recommended by73%of homeowners
Avatar for Proper Environmental
Proper Environmental
5.0(
6
)
Radon Gas - AbatementRadon Gas - Testing

Serving O Fallon, MO and surrounding areas

Free estimates

Credit card accepted

"It went great! They set up a system in my parent's house and they mitigated the radon down to a save level. They did a test before and after, and I was satisfied with the results. Proper Environmental did a thorough job and would recommend this company to anyone!"
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+3

Recommended by100%of homeowners
Avatar for Greensmith Home Inspection, LLC
Greensmith Home Inspection, LLC
4.6(
36
)
Radon Gas - Testing

Serving O Fallon, MO and surrounding areas

In business since 2017

Free estimates

Credit card accepted

"We wanted the house inspected because we were buying it. He did a thorough enough job of examining the outside and inside of the house. One thing that he didn't do... He didn't pull some building materials away from the basement storage area to examine the basement wall for cracks. I was a little surprised about that. He also didn't notice that the basement door was getting stuck when we tried to close it. We noticed it ourselves and asked the current homeowner's to fix it. However, he did notice the slow drain in the master bath. A leaky window in the master bedroom and that their was no GFCI outlet in one of the bathrooms. He tested for water/dampness in all the rooms and all of the windows. He communicated well and arrived on time. He took about an hour outside and inside. Also looked for termite problems in the house as well. Overall, I would hire him again."
Appliance Serial Number Capture
Response time2 hrs
Recommended by93%of homeowners
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Radon Detection and Reduction FAQs, answered by experts

The natural breakdown of uranium in soil, rock, and water can cause radon to appear in a home. The gas seeps into homes through cracks in foundations, walls, or floors, as well as through gaps around pipes or construction joints. Radon levels are influenced by soil composition, building materials, and ventilation. Poorly sealed or airtight homes can trap radon, allowing it to accumulate.

Radon is the number one non-smoking cause of lung cancer in the United States, but it can cause some other concerning side effects in the meantime. If you have a raspy voice, chest pains, trouble breathing, difficulty swallowing, or any of the above, don’t hesitate to perform radon testing and install a mitigation system as soon as possible.

You'll need to test your home for radon after installing the mitigation system, then again every two years. If radon remains elevated, contact a licensed radon professional, either the contractor who installed the system or a different one, and have them evaluate the system. They may need to make some changes to improve its effectiveness and performance.

The cost for a radon mitigation system typically ranges from $800 to $1,500, with an average around $1,000. The final price depends on several factors, including the size of your home, the severity of the radon issue, and the type of system required. Your home's foundation type also significantly impacts the cost. For example, sealing and ventilating an unfinished basement might cost around $4,600, while encapsulating a crawl space without a foundation slab can range from $1,500 to $15,000.

Long-term exposure increases lung cancer risks. Prolonged homestay individuals and smokers encounter heightened vulnerability and exposure concerns.

The O Fallon, MO homeowners’ guide to radon detection and reduction services

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