Mitigating radon gas in homes

Radon gas in homes is a growing health concern. Adding a passive radon stack is always a good idea to prepare a home for better indoor air quality.

Installing a radon evacuation stack in a slab floor
Installing a radon evacuation stack in a slab floor © Ecohome

Radon gas builds up in homes and has serious health effects. Reducing radon in homes is cheap and easy with a slab floor barrier with proper sealing at junctions and evacuation stack.

Radon (Rn) is a natural gas resulting from the decay of uranium, present everywhere in the earth's crust. Outside, the gas is released into the atmosphere where its concentration is of no concern.

How radon enters a home
How radon enters a home © Ecohome

Modern construction techniques have us building homes far more airtight than in previous decades for reasons of durability (condensation in wall assemblies), and also for energy efficiency, as air leakage used to account for about 1/3 the total heat loss of a home. The lack of fresh air leaking in and out means radon now collects in homes at higher concentrations and it has become a greater health concern.

Radon is colorless and odorless and can be present in any home without humans being able to realize or detect it. Radon gas exists everywhere, but some regions have much higher concentrations than others.

study by Health Canada over two years showed that 6.9% of Canadians live in homes where radon concentration exceeds this line radon guideline of 200 Bq / m3. Health Canada advises homeowners to evaluate radon levels of their properties and investigate ways to mitigate it. Radon mostly enters through the basements, and the natural stack effect of homes means air from the basement will find its way to the top floors. More specifically, radon penetrates through:

• Stone foundations

• Crawl spaces

• Floor drains

• Un-sealed sump pump housings

• Cracks, gaps and joints in walls, floors, ceilings

• Openings around pipes

• Well Water

Is there radon in water?

Yes, unfortunately radon is water-soluble and can enter homes that run on well water, particularly as water is aerated by showers and sinks.

What are the health effects of radon gas?

Exposure to radon is the second greatest cause of lung cancer after smoking, estimated to account for about 10 % of all cases of lung cancer.

According to Health Canada, "the only known health risk associated with exposure to radon in indoor air is an increased risk of developing lung cancer." It depends on the average concentration of the gas in the building, of the duration of exposure and smoking. The exposure does not cause other known disorders such special breathing problems or headaches. If ingested, radon is harmless.

Protecting air quality from reduced radon levels is easily done as new homes are being constructed, it becomes a bit more tricky retrofitting older homes.

Radon evacuation stacks:

A radon stack can be passive or active. A properly installed sub-slab barrier and passive stack is a great start, and in higher risk areas or with trickier situations of retrofitting existing homes, a fan can be installed in the stack that increases the draw. 

New home passive radon evacuation stacks:

Before concrete slabs are poured, the addition of a well sealed vapour/radon barrier and a simple PVC tube and a T-junction can give radon gas an easy escape route. It is a very simple and low-cost procedure that has great results in reducing radon levels in homes simply due to the natural stack effect. An electrical junction box should be located near the stack in order to allow for the installation of a fan if testing of the home reveals that it is necessary.  

Radon mitigation in existing homes:

Depending on the state of your basement and or crawlspace, there will be varying degrees of difficulty in mitigating radon. Crawlspaces can often be fitted with a radon stack and membrane barrier, finished basements and those with already poured concrete floors will probably prove a bit more difficult. As the awareness of the danger of radon gas becomes more common, you are not left to deal with this on your own as contractors are regularly popping up that specialize in reducing home radon levels.

For an understanding of how easy it is to install a radon stack, see the following video.