In Existing Homes:
After testing for radon and if the level exceeds 4.0 picocuries, the next step is to begin mitigation. You should look for a ‘certified mitigation contractor’. They will have completed the EPA required training and testing. In a nutshell mitigation for an existing home includes the following:
- Cover all exposed earth with a 6 mil poly and seal all edges.
- Caulk all cracks and openings in the floor slab.
- Put a 3” pipe in the earth, thru the floor slab, or in a sump.
- Install the pipe inside or outside the house.
- Extend the pipe a 12” above the surface of the roof.
- Pipe must terminate minimum of 10’ from a window
- Pipe must terminate 10’ from another home.
- Re-test and verify a level of 4.0 picocuries or less.
In New MN Homes:
There is no preliminary testing. The state requires either a passive or active system that consists of the following construction requirements:
Below the floor slab a minimum of 4” of gas –permeable aggregate or sand.
- Cover the sand or aggregate with a minimum 6 mil poly overlapped a minimum of 12”.
- All penetrations thru or joints in the slab must be caulked.
- Hollow core blocks must have at finished grade a solid course of blocks.
- Exterior walls of foundation must be dampproofed below grade.
- Ducts below the slab must be continuous or sealed.
- A plumbing tee inserted below the floor slab and poly.
- A minimum 3” pipe extended thru the building and marked as radon pipe.
- Pipe must terminate 12” above the roof and a minimum of 10’ from a window or another house.
- A fan (active) is optional. No fan (passive) or radon testing is required.
Radon gas is real…this hazard should be taken seriously.
‘Like’ Cities Inspection’s Facebook page for more great tips on things to watch for in your home!