Full Guide to Professional Radon Testing for Home Inspectors

January 19, 2023 | 
radon test

When shopping for a home, most buyers have already been told how important it is to have a home inspection completed before closing the sale. But what many buyers may not realize is that it’s also a good idea to have radon testing conducted within the home as well.

Measuring the indoor radon levels will give the homebuyer insight into an important aspect of a home’s air quality and let them know if their dream house has a radon problem. If it does, their agent can work to negotiate the price down to cover radon mitigation costs.

What if someone already owns their home but has never had radon testing performed before? It’s never too late to take care of this important health and safety precaution. It’s easy for homeowners to purchase a radon kit from the hardware store, but it’s even better for them to call a professional Home Inspector who is also certified to perform the radon test.

This article will help you better understand how and why radon house inspections can help your business, as well as your clients’ wellbeing.

What is radon?

Radon is a colorless, odorless gas that occurs naturally in the earth. As elements like uranium and radium break down in the rock and soil beneath homes, they release radon gas.

A reminder for anyone struggling to recall high school chemistry class: uranium and radium are radioactive. The same is true for radon gas, which can cause lung cancer — in fact, radon exposure is the second leading cause of lung cancer in the United States.

Radon isn’t a problem outdoors, because it quickly dissipates into the atmosphere, leaving only miniscule amounts in the air you breathe. But if your house is tightly sealed — as many modern homes are, thanks to high-quality insulation and efficient air sealing — you could be at risk. That’s because radon can become trapped inside and build up to unsafe levels.

Because radon is odorless and invisible, the only way to know if you have a problem is to conduct a radon gas inspection. Both the Centers for Disease Control (CDC) and the Environmental Protection Agency (EPA) recommend checking the radon level in your home for safety, even if you don’t live in an area of elevated risk.

What is radon testing?

A radon kit is used to test radon gas levels and radioactive particles and measure them in order to estimate the total amount of radon in the home’s air. Because radon gas rises up from the ground, your radon testing device should be placed on the lowest level of the home that is typically occupied: the first floor in most buildings, but the basement if it’s finished to provide living space.

In general, there are two different types of radon testing: active and passive.

Passive Radon Tests

The most common passive test is a charcoal canister. These tests contain activated charcoal that absorbs radon gas and is then sent to a lab for measurement. As the name suggests, a passive test sits in the home for the collection period (typically 48 hours, but some tests last up to a week). It’s important to keep windows closed for the duration of the test so you get an accurate result. A high radon level would be “hidden” from the test if the windows were left open because the gas would escape and leave you with a false reading.

Active Radon Tests

An active radon testing device is a meter that remains plugged in to provide continuous monitoring of your home’s radon levels. These need to be professionally installed and are useful for understanding how radon levels change over time. They can be used for short-term or long-term testing, allowing the Inspector to tailor the tests to the homeowner’s needs. An active radon monitor is often part of a full radon mitigation system installed to reduce radon levels in the home. The radon detector lets you know the system is working as designed and that the home remains protected.

Though there are hardware store radon testing kits that are convenient, it’s not the most accurate or complete measure of radon in the home. These kits tend to be small, and their placement can determine what type of reading you get. Hiring a professional will help ensure that accurate results are obtained.

When you get your radon test results, the measurement will be in picocuries (pCi/L). According to the EPA, any home with more than four picocuries of radon per liter of air should have radon mitigation performed to reduce dangerous gas levels. The World Health Organization (WHO) recommends taking action at 2.7 picocuries.

What does a professional radon testing home inspection include?

A professional radon inspection will typically include the certified Home Inspector using one or more radon detection monitors in the home. These monitors will assess the current levels of radon in the soil, air, and/or water and how it is affecting the air inside the home. Here is an overview of types of devices that may be used during the test.

Electret Ion Detectors

This radon detector is lab-produced and has a Teflon disc inside, which undergoes charging with static electricity. The decay of materials that causes radon gas is ionic and will be immediately attracted to the Teflon disc, causing the electric charge to drop as more radon comes into contact with it. After testing is complete, the disc’s final charge level will be compared to the starting charge level to determine the level of radon in the home.

Alpha Track Detectors

The alpha track detector includes a layer of film, usually made of plastic, that is used to catch alpha particles, which leaves a mark on the film. At the end of the test, a chemical treatment can be used to make each mark visible to the professional Inspector, who can then see if there are a lot, or only a few, marks left from the alpha particles.

Charcoal Liquid Scintillation Device

This device, also called a charcoal canister, has a charcoal filter that absorbs radon throughout the duration of the test. After the full time period of the test has elapsed, the test is sent to a lab where a liquid scintillation medium will detect how much radon has been absorbed.

Continuous Radon Monitor

The continuous radon monitor is an active test, unlike the three examples above, which are all passive tests. This monitor can detect the changing levels of radon alone, or a Home Inspector may opt to use this in conjunction with another type of radon test.

How to test for radon during a radon inspection?

Professional radon testing includes examining of all potential causes of radon exposure, including the soil around the home, sometimes down to the third layer of the earth. Some inspections call to check for radon-contaminated water, which involves checking any private wells, public water supplies, and any groundwater sources.

The inside of the home is always tested during a radon inspection, and involves using radon monitors that are either passive or active tests. Prior to choosing which monitor is best for the home’s test, the Home Inspector and homeowner must discuss whether they are conducting a short-term or a long-term test for radon levels.

At the end of the testing period, if high levels of radon are detected, a comprehensive plan to resolve the issue and make the home safe must be created.

Do’s and don’ts of radon home inspections for Home Inspectors

Do: Place the test on the lowest level of the home that is suitable for living

Since radon gas can creep into the home from the ground underneath the home, it is best to keep the radon monitor on the level that is closest to the soil and rock in which the gas may be coming from. Placing the monitor in the basement, if finished, or the first floor in a regularly used room will deliver the most accurate results for the homeowner.

Don’t: Place the test in a kitchen, bathroom, hallway, or laundry room

Although the homeowner must agree with the Inspector on where the monitor is placed during the duration of the test, it is important that the Home Inspector not allow the monitor to be placed in a kitchen, bathroom, hallway, or laundry room to avoid humidity or excess heat. For the most accurate results, the monitor must be placed in a room such as a bedroom, den, living room, or family room on the lowest level of the home that is suitable for living.

Do: Keep windows and doors to the outside closed if conducting a short-term test

When conducting a short-term test, typically over a couple of days, it’s important that the home’s windows and doors to the outside, except for normal entry and exit, are kept closed to ensure an accurate result. If too much outside air is brought into the house, the levels read on the monitor may be lower than they typically are, giving a false sense of security and safety to the homeowner.

Don’t: Conduct a short-term radon inspection during a storm or high winds

Having a storm or very windy weather will greatly affect the results that are found from a radon inspection. Since the radon gas originates from outside, it can be easily altered from extreme weather. For best results, avoid scheduling a radon test if stormy or windy weather is forecasted during the period of time the monitor needs to be in the home.

Do: Place the test at least 20-inches from the floor, and away from any disturbances

For accurate results, the radon test needs to be placed in a spot that is away from drafts, high humidity, high heat, exterior walls, and from anywhere it might be disturbed. Once the test begins, it needs to remain in the same spot, untouched, for the duration it requires.

Don’t: Run any air-moving devices during the testing period

Running devices such as ceiling fans, dehumidifiers, standing or table-top fans, HEPA, or any other kind of filtering device that moves air will only influence the test results and not allow the homeowner the opportunity to receive accurate results.

What radon Inspectors should know about radon mitigation

Radon mitigation — also known as radon abatement — is a system that reduces radon levels in the home. While it’s not possible to eliminate radon entirely, a radon mitigation system helps to expel the gas from the home to keep concentrations low.

Often, the system consists of a pipe that is sunk through your basement floor and into the soil beneath your house. The pipe may continue upward through the home to an exit point on the roof, or it may exit the basement and continue upwards along the outside of the house.

Attached to the pipe is an exhaust fan that draws air from under the ground, through the pipe, and out the other end. The idea is that any radon gas being released underground will be sucked out of the home through the pipe and allowed to safely dissipate in the air outdoors instead of becoming trapped in the living space.

The cost of radon abatement is a major reason why good real estate agents will often suggest a radon test along with the home inspection. If the homebuyer knows ahead of time that radon is an issue in the house, their broker can ask the seller to reduce the price to cover the cost of abatement. Many sellers will be willing to do this to close the sale, especially because future buyers are likely to make the same request as well.

A note for sellers:

It makes sense for sellers to conduct a radon test, too. Just as a pre-listing inspection can help zero in on which fixes to invest in, so can a radon test. If the test comes back with great results, the home can be advertised with the low radon numbers in the listing. And if the results show that radon mitigation is in order, the seller’s agent can advise whether it makes sense in their market to invest in a radon reduction system before putting the home on the market.

A note for homebuyers:

If a homebuyer has never had a radon test when buying their house, it’s never too late! Remember, the EPA recommends that every home be tested, since radon is a major cause of lung cancer. Knowing what the radon levels are in the home will let the homeowner know if they need to look into a mitigation system for their safety.

Final points on conducting home radon tests

Testing a home’s radon levels is very important, and getting the test done by a certified professional is just as important as the test itself. There are a few options to choose from when deciding which type of radon monitor to invest in and use at your customers’ homes, but following the instructions and knowing the dos and don’ts when conducting a test will be key to retrieving the most accurate results.

Frequently Asked Questions

What homes are at higher risk for radon?

There isn’t one type of home that is at a higher risk for having high radon levels. Whether the home is old, new, drafty, well-insulated, or with or without a basement, all homes can develop high radon levels. Some states have higher radon levels than others, but radon gas has been detected in all 50 states, making it important for all homeowners to get their homes tested.

What causes radon in homes?

Typically, what causes radon in homes is what is underneath the home. The soil and rock that is underneath your foundation can contain radioactive elements that naturally decay and create radon gas, which usually dissipate into the outdoor air but can leak into your come through gaps and cracks.

What time of year is radon highest?

During the winter is when indoor radon levels are normally at their highest. The cold temperatures outside can cause the pressure inside the home to increase, which means more air from the ground will be pulled in. This greatly increases the chance of radon entering the home.

The winter months is also when homeowners typically don’t have their windows open to allow the outdoor air inside, which helps circulate and clean the air inside during the warmer months.

What radon detectors should Home Inspectors use?

Investing in the right equipment to start radon inspections is important and there are plenty of options to choose from. When looking at the different types of radon testing monitors, there are passive devices — such as charcoal tests, alpha track detectors, carbon liquid scintillation detectors, and electret ion chamber detectors—and active devices—such as continuous radon monitors (CRMs) and continuous working level monitors. The type of monitor that is used is typically based on preference, along with the types of tests that the Inspector plans on offering – either short-term or long-term radon tests.

How much should professional radon gas testing cost?

In the U.S., a radon inspection can range between $150 and $700, averaging at around $400 for each inspection. Although home test kits can range between $10 and $30, hiring a certified professional will the best way to receive accurate test results.

Where should the radon test be placed?

The EPA recommends that the testing device be placed within the lowest level of the home that is suitable for occupancy, such as a finished basement or the first level if there is no finished basement. Is it best if the test is placed in a room that is used regularly, such as a family room, living room, or bedroom; but should NOT be placed in a kitchen, bathroom, laundry room, or hallway.

Subscribe For Updates

Sign up to get the latest HomeGauge news, learning articles, and announcements sent directly to your email inbox.

Start inspecting today with our speedy, connected Web Writer.

Try HomeGauge for just $9.90/mo for 3 months!