Radon gas is found naturally in the environment and comes from rocks, soil, or water.

When you call an inspector to ask about scheduling your home inspection on a house you are going to buy, he or she will probably ask you if you want a radon test.

Should you do it?

In most cases, yes.

Whether you live in a house an old house or new house, a house with a basement or on a slab, in the country or in the city, it is still a good idea.

Here are some common questions and answers about radon gas that may help you navigate this part of the home buying process:

What is Radon?

Radon is an invisible, odorless radioactive gas that occurs naturally. It is released from rock, soil, and water.

Why is Radon a Problem?

Radon gas can build up in one’s home. Radon is a known carcinogen and can increase one’s risk of getting lung cancer. It is actually the second leading cause of lung cancer after smoking.

How Common is Radon Gas in Vermont?

One in seven homes in Vermont tests high for radon gas. Radon gas is found in homes in every state, and nationally an average of one in five homes tests high for radon gas.

Are Older Houses More Prone to Radon?

Radon gas can be found in homes of all ages and sizes. Even brand new constructions can test high.

Some people who buy new homes opt out of a structural building inspection (something I generally do not advice but is common nonetheless), but even if you decide not to do a structural inspection, you still may want to test for radon gas.

Do I Have the Right to Perform a Radon Test on a Home I’m Buying?

Most Realtors will advise you to put a radon contingency into your home buying contract. This contingency says that you have the right to have a radon inspection within a certain number of days of the contract date. If you are dissatisfied with the results of that inspection, you have the right to terminate the contract.

If this provision was put in this contract, you have the right to conduct the test during the specified time period, but you are also not obligated to do the test if you later decide not to.

How Does a Radon Test Work?

Usually the radon test is scheduled at the same time as the general structural inspection.

The inspector will usually request that sellers are alerted beforehand that all windows are closed for at least 12 hours prior to his or her arrival.

While it is okay for people to come in and out of the house and open doors during this period, it is important to reduce the amount of airflow coming in and out of the house by shutting the doors promptly.

When the inspector arrives, he or she will usually place the testing kit on the lowest floor of the home.

While the structural inspection can usually be completed in a couple of hours, the inspector will typically leave the radon test in the house for 2-3 days and then come back to pick up the results. During this 2-3 day period the windows must continue to be kept closed.

Sellers will sometimes complain about these restrictions, especially in the summer. It does get hot in Vermont in summer and many people don’t have air conditioning. Still, the radon test is important, and it is reasonable to ask sellers to follow instructions.

After the 2-3 period, your inspector will come back to pick up the test. You should receive the results shortly thereafter.

How Much Does a Radon Test Cost?

In our area, most inspectors charge an additional $100-$150 to do a radon test on top of the regular home inspection.

How High is Considered an Elevated Radon Level?

The results are measured in pCi/L. The US Surgeon General and EPA recommend fixing homes with levels above 4 pCi/L.

What Happens if the House Tests High for Radon Gas?

If the home you are hoping to buy tests high for radon gas, a radon mitigation system can be installed. Radon mitigation systems are generally extremely effective and can reduce radon levels significantly in almost any home.

How Much Do Radon Mitigation Systems Cost?

The average cost to install a radon mitigation system is $1,200 with a typical range of $800 to $1,500.

Who Pays for a Radon Mitigation System?

If you discover a home has high radon gas (over 4 pCi/L) during the inspection process, it is reasonable to ask the seller to pay to install a radon mitigation system.

However, you should note that they have no legal obligation to do so and may refuse.

If your level tested on the higher side of the normal range (2-4 pCi/L), you may still want to consider a radon mitigation system, but you are very unlikely to convince the sellers to pay.

Are There Cases Where it Doesn’t Make Sense to Make Radon Testing a Condition of the Sale?

There may be reasons that you forego making a radon gas test a condition of the sale. If you are purchasing a vacation home, for example, where you only plan to spend a few weeks per year in a home, it may not be worth it.

Alternatively, if you are in a multiple bid situation and trying to make your offer stand out, you may decide you don’t need to make the radon test a condition of the sale. However, it still may be a good idea to get the home tested once you move in.


Radon gas is relatively common in homes in Vermont and can pose a real health threat. The good news is, radon can be relatively easily mediated. The best practice is to get your home tested for radon gas.

It is important to feel safe in your home and make sure that your health isn’t at risk because of your indoor environment.

No matter what kind of home you live in, testing for radon is an important part of achieving that.


Pallas Ziporyn is a Realtor based in Burlington, VT. She is the founder and head writer for The Vermont Real Estate Blog, and she works with both buyers and sellers in Chittenden County and surrounding areas.

In addition to her real estate pursuits, Pallas enjoys being involved in the local community, skiing, writing, and spending time with her husband Chris and their two small children, Leander and Hugo.