Crawlspace radon mitigation in Huntsville, Alabama
Many homes in Huntsville and Madison County sit over a crawlspace, and radon from the soil under it can be pulled up into the living areas. The EPA says the most effective fix for most crawlspace homes is a sealed plastic sheet over the soil with suction underneath. Tell us about your home and we will connect you with an independent contractor who does this work.
Why crawlspace homes still need a radon test
A crawlspace does not shield a home from radon. Air moves upward through a house, drawing soil gas in from the crawlspace through gaps around floors, ducts and plumbing. Test the lowest lived-in level of the home, not the crawlspace itself, because that is where you breathe the air.
The EPA recommends fixing a home at 4.0 pCi/L or higher and says to consider fixing between 2.0 and 4.0 pCi/L. Madison County is in EPA Radon Zone 1, the highest-potential zone. See our radon testing guide for how to test.
How radon is reduced in a crawlspace
Sub-membrane depressurization
Plastic sheeting covers the soil and is sealed to the walls. A pipe and fan draw radon from under the sheeting and vent it above the roof. The EPA describes this as the most effective method for crawlspaces.
Crawlspace ventilation
Vents or fans move outdoor air through the space. It can help, but it may raise heating and cooling costs, and pipes may need insulation in cold weather.
Active crawlspace depressurization
A fan pulls air from the crawlspace itself. The EPA rates it less favorable because of energy costs and concerns about combustion appliances.
The EPA says active soil depressurization systems can reduce radon by 50 to 99 percent. Sealing cracks alone is not recommended as a stand-alone fix.
What installation involves
Inspect the crawlspace
The contractor checks the soil, walls, moisture and any standing water or exposed wiring.
Lay and seal the membrane
Heavy plastic sheeting is laid over the soil and sealed to the foundation walls and piers.
Run the pipe and fan
A suction pipe is placed under the sheeting and routed to a fan in an unconditioned space, venting above the roof at least 10 feet above the ground.
Add a warning device
A gauge or alarm shows whether the fan is working.
Retest
Test at least 24 hours after the fan is running, ideally within 30 days.
Questions to ask a crawlspace contractor
- Are you certified in radon mitigation (NRPP or NRSB) and do you follow any state requirements?
- Will you inspect the crawlspace before giving a price?
- Do you use sub-membrane depressurization, and how is the sheeting sealed?
- Is insurance and bonding in place, and what is guaranteed in writing?
- Is the warranty transferable if I sell the home?
The EPA suggests getting more than one estimate.
What crawlspace mitigation costs
The EPA says radon reduction typically costs about the same as other common home repairs, such as painting or replacing a water heater. The price depends on crawlspace size, condition, and where the pipe can run. A contractor can give a firm price after reviewing your home.
After the system is installed
- Keep the fan running at all times. Do not switch it off.
- Check the warning device regularly.
- Retest every two years, and after changes to the foundation or airflow.
- Fans commonly last five years or more, and warranties are rarely longer than five years.
Crawlspace radon questions
Do I test the crawlspace or the house?
Test the lowest lived-in level of the home. That reflects the air you actually breathe.
What is the best radon fix for a crawlspace?
The EPA says sub-membrane depressurization is the most effective method for most crawlspaces.
Is crawlspace ventilation enough?
It can reduce levels in some homes, but it may raise energy costs and pipes may need protection in cold weather. Retest to confirm results.
Can I just seal cracks?
The EPA does not recommend sealing as a stand-alone fix, because it is hard to seal every opening.
How long does installation take?
Many installations take a day or less. Crawlspaces that need repairs or have difficult access can take longer.
How do I know it worked?
Retest at least 24 hours after the fan is running, using an independent tester if possible, and retest every two years.
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