How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manufactured and modular homes

How do you reduce radon permanently?

Sunday, October 7, 2018

Radon mitigation is defined in Wikipedia as: “Any process that is used to reduce radon concentrations in the breathing zones of occupied buildings.” To understand how a radon mitigation contractor reduces radon, let’s start by reviewing what causes an elevated radon level in the first place. Radon is a colorless and tasteless gas that results from the radioactive decay of naturally-occurring uranium and radium in the soil.

   As the gas is created, and rises up out of the ground, it enters a typical home through any openings in the floor slab, such as where pipes come up into the house,  or shrinkage and settlement cracks in the slab that occur over time. After radon enters a home, it decays into radioactive particles that have a static charge, which attracts them to particles in the air. These particles can get trapped in your lungs when you breathe; and, as the radioactive particles break down further, they release bursts of energy which can damage the DNA in lung tissue. If the lung tissue does not repair the DNA correctly, the damage can lead to lung cancer. 

   It’s important to understand that a low level of radon is in the air we breathe everywhere and every day. But, if there are higher levels of radon coming out of the soil directly under the home, the radon can collect in the enclosed space of the residence and reach levels that the Environmental Protection Agency (EPA) has determined are unsafe.

      The two primary ways to reduce the radon level are: 1) to seal openings in the floor where radon is entering, and 2) create a system that uses negative-pressure (low-level suction) to draw the radon to a pipe under the floor slab--before it can enter the house--and vent it out above the roof. Most contractors use a combination of both techniques, and each vent pipe is placed in an unobtrusive location, like the corner of a closet. Sometimes it is run along the outside of a house, as in the photo below.

    Radon mitigation typically costs between $2,500 and $5,000, with the variables determining cost being square footage of home, shape of the footprint of the home, and how high the starting radon reading is. Sometimes a contractor is unable to bring the radon below the level of 4.0 pico-curies per liter of air level that the EPA considers acceptable with their initial work, and they have to come back and do more. So it’s a good idea to get a price from the contractor that guarantees that, for the agreed price, they will bring the level below 4.0 without additional charge. 

   Not sure whether testing for radon is worth the cost? Before you decide, read our blog post How can not testing for radon be an expensive mistake for homebuyers?

• • • • • • • • • • • • • • • • • • • • • • • • • • • • •

Here’s links to a collection of our blog posts about “RADON":

 Is a radon mitigation fan required to be on a dedicated circuit breaker/fuse in the electric panel?

What happens to a radon test result if the windows were opened, the test device moved, or there was any other evidence of tampering during the test? 

Where do I find the Florida laws regarding radon?

Can I test vacant land for radon before building a house? 

Is radon mitigation possible for a condominium?

Do radon mitigation systems require maintenance?

What is the average life expectancy of a radon mitigation system?  

Do older houses have higher radon levels than new houses? 

Can the seller tamper with a homebuyer's radon test to change the results?

How long does it take to get the results of a radon test? 

Will opening the windows reduce the radon level in a house?

How was it determined that between 15,000 and 22,000 lung cancer deaths each year are caused by radon?

Can a homebuyer do their own radon test for a real estate transaction with a self-test kit?

What is the danger of radon in well water?

What are the symptoms of radon poisoning? 

Does Florida have radon?

Where does radon come from? 

For how many years does an old radon test result remain valid?

Should homeowners get a pre-listing radon test before selling their home?

What are a homebuyer's options when the radon test comes back high (4.0 pico-curies/liter or more)? 

Do granite countertops emit radon?

How can I tell if a house has a radon mitigation system? 

Can a mobile/manufactured home have a high radon problem?

Do I need to test for radon when buying a condominium? 

Will the radon test come back sky-high in a house that has been empty and closed-up for months? 

What is radon? Should I be concerned about it?

Should I buy a house with a high radon level? 

What is the average radon level of indoor and outdoor air in America?

What is the operating cost of a radon mitigation system? 

• Should I buy a house with a radon mitigation system?

• Does the buyer or seller of a home pay for radon mitigation when the radon test comes back high? 

• What is the probability of having high radon in a Florida house?

• How quickly do I need to reduce a high radon level in my house? 

Does a home inspector check for radon?

What are the problems with underground return air ducts? 

• What is the probability of having high radon in a Florida house?

• What factors can change radon test levels up or down?

    Visit our RADON page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

Water Heaters

Water Heater Age

"What Are The

Signs Of..."

Septic Tank Systems

Structure and Rooms

Plumbing Pipes

Termites, Wood Rot

& Pests



When It First

Became Code

"Should I Buy A..."

Park Model Homes


Shingle Roofs




Wind Mitigation

Roof and Attic

"Does A Home


Pool and Spa

"What Is The Difference Between..."




Concrete and

Concrete Block

Metal Roofs


Modular Homes

Rain Gutters

Mold, Lead & Other Contaminants


Older and

Historic Houses

Crawl Spaces

Mobile-Manufactured Homes

Building Permits

Life Expectancy

Clay Soil





Exterior Walls

& Structures


Common Problems

HUD-Code for

Mobile Homes

Garages and Carports

Flat (Low Slope) Roofs

Electrical Panels

Sprinkler Systems

Electrical Receptacle Outlets

4-Point Inspections

Hurricane Resistance

Frequently Asked Questions (FAQ)

Home Inspection

Heating and Air Conditioning

Building Codes

Fireplaces and Chimneys

Inspector Licensing

& Standards

Energy Efficiency

Washers and Dryers



Doors and Windows



Electrical Wiring

Click Below  

for Links

to Collections

of Blog Posts

by Subject

Plumbing Drains

and Traps


Smoke & CO Alarms

Aging in Place

Top 5 results given instantly.

Click on magnifying glass

for all search results.






Air Conditioner & Furnace Age/Size


Electrical Switches





Water Intrusion

Electrical - Old

and Obsolete


Foundation Certifications

Tiny Houses

About McGarry and Madsen



Buying a home in North/Central Florida? Check our price for a  team inspection by two FL-licensed contractors and inspectors. Over 8,500 inspections completed in 20+ years. In a hurry? We will get it done for you.

Moisture Problems

Crawl Spaces