How To Pass A Radon Test When Selling Your Home

It is important to test for radon levels in a home before selling it. In fact, many states in the USA mandate that a radon test should be done and the results should be documented before selling a home.

The buyer can request radon tests during the home inspection. If the radon levels are found to be over 4 pCi/L, one should take steps to mitigate it.

What does it mean to pass a radon test?

A house passes a radon test if the radon levels inside it are tested to be below 4 pCi/L. If the levels are above this value, the buyer or the seller of the house should take steps to mitigate it.

If the levels are found to be between 2 and 4 pCi/L, EPA advises taking measures to reduce them. However, during the sale of a house, the owner is not liable to do this as it is below the unsafe level. The buyer can take steps to reduce the levels once the home is bought.

How to pass a radon test?

A radon test can be beaten by reducing the radon levels in a home. However, radon tests are conducted by keeping the house closed. Therefore, any method you adopt for radon reduction should be able to work in such a scenario. Here is how you can reduce radon levels and beat a radon test;

  1. Seal all the entry points of radon into the home
  2. Install vapor barrier
  3. Avoid house depressurization
  4. Use air to air heat exchangers
  5. Install a radon mitigation system

Seal all the entry points of radon into the home

Radon gas enters a home through the foundation, the soil outside, and through cracks in the walls. By sealing the cracks in the walls and the foundation, you can reduce the flow of radon into the house.

If you have a sump pump, it also should be sealed and made air-tight. Sump pits have high levels of radon content as it provides an easy path for the radon to enter the house. By sealing the sump pump, the entrance of radon into the basement can be prevented. There are many sump pump covers compatible with radon mitigation systems that you can use for this purpose.

These measures should be done at least a week before the radon test. Once all the entry points are sealed, the house should be ventilated regularly by opening all the windows. This will vent all the radon gas remaining in the house.

Install a vapor barrier

Another good method to reduce radon inflow before testing is installing a vapor barrier. This is an effective method, especially if you have an unfinished basement or a crawl space. A vapor barrier is basically a plastic sheet. Lay a few of them flat on the floor, sealing any overlaps, and seal them to the walls. As the radon gas cannot pass through this vapor barrier, it will stay trapped under the sheet.

A vapor barrier should be installed at least a week before conducting a radon test. You should also make sure to vent all the radon gas inside the house before the test.

Avoid house depressurization

Houses have negative pressures when compared to the outside. As you know, air flows from a high-pressure area to a low-pressure one. This means the house will act as a vacuum that sucks the radon gas from under its foundation. By reducing this low pressure inside the house, the rate of radon entering the house can be reduced.

While houses already are a negative pressure zone, this can be further increased by the use of power ventilation fans. Exhaust fans in your bathrooms and kitchens, and whole-house fans force the air out of your home creating negative pressure zones. These negative pressure zones will accelerate the entrance of radon gas into the house.

Therefore, to pass a radon test, you should avoid the use of forced air ventilation.

You can also further reduce radon levels by pressurizing the basement of the house with a fan. Once the basement develops a positive pressure, the radon gas will have to find a different way to escape into the atmosphere.

Use air to air heat exchangers

Air-to-air heat exchangers can reduce the radon levels in a home. Such an exchanger installed in the basement exhausts the radon air inside and replaces it with the fresh air from the outside. Since the exchanger heats the fresh air, there will be no major energy losses. In addition, as fresh air is drawn in simultaneously while the radon air is exhausted, this setup does not develop a negative pressure inside the house.

Once the steps to reduce radon levels are taken, test the home with a short-term test kit and see if the levels are within safe limits. If they are still high, discuss with the buyer about installing a radon mitigation system.

Install a radon mitigation system

If the radon levels are still high in your home, either the buyer or the seller will have to install a radon mitigation system. There are different types of mitigations systems. They are selected based on many factors like radon entry points, existing radon levels etc. A typical sub-slab pressurization system can cost anywhere from $1200 to $1800. Usually, a buyer pays for the installation however, it is not required of him. The buyer and the seller can also come to an agreement about splitting the costs of the installation.

How to cheat a radon test (Buyers beware)

If you are thinking of manipulating a radon test, don’t bother. Contractors who conduct radon tests for real estate transactions know what they do. And they are very well-experienced people trying to cheat the tests all the time. However, if you are keen on cheating, here is what you can do;

Sell the home in summer.

The radon levels in a house vary with seasons. These levels are usually higher in winters and low in summers. Radon levels also tend to be high with high humidity and rain. So when you are selling a house, sell it at a time when the radon levels could be low.

While the independent contractors who run the tests know of this, most do not bother to inform the buyer. For most of them, if the levels are below 4.0 pCi/L, it is a pass. This is true even if the levels are 3.9 pCi/L, just 0.1 short of the danger level.

For this same reason, a buyer should be asking for more data on radon levels. While it is not always possible to find a dream home in winter, it pays to prepare ahead. If the radon levels are anywhere above 3 pCi/L, inquire whether any steps were taken for radon mitigation. Inspect the basement to see if there is any vapor barrier installed.

If you think the levels could exceed the limits during the seasons, discuss the issue with the contractor. You can also take the matter to the seller and ask him to get a mitigation system installed. It is not liable for the seller to install this, however, both of you may come to an agreement about splitting the installation costs.

How does a contractor run a radon test for selling a home?

A third-party contractor tests the home for radon if the buyer requests it. These contractors typically use expensive continuous radon test devices to monitor the radon levels in the home for a duration of 48 hours. The test kits are placed in a location that possibly has the highest radon levels. The house should be kept closed during the test to avoid any ventilation. However, all the HVAC systems should be run as normal.

The test kit should not be disturbed during the testing process. Acts like opening a window, or moving the test kit can alter the radon readings. A contractor will know if any such things are done as the continuus monitoriing devices will record abrupt changes in radon levels. He will inform teh buyer about it, and you will have to run a second test.

Charles John

A novice DIYer who learns about home ventilation. I am a mechanical engineer and have a basic knowledge of HVAC systems but I learn continuously to make myself the best blogger in that space.

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