Radon Testing Protocols

Does your radon tester follow the EPA guidelines?

In a real estate transaction most radon tests are performed by the home inspector. There is nothing wrong with that, but there is the assumption that they are doing it ‘right’. This may or may not be true. The proper testing protocol you should expect is the following:

  • Homeowner contacted to discuss the test and EPA rules.
  • The house closed up, doors and windows shut, a minimum of 24 hours before test.
  • Set the monitor at the lowest potential habitable level of the home.
    •    Approximately 3’ to 6’ off the floor.
    •    Centrally located and not on outside walls.
    •    3’ from a furnace supply or return air register.
    •    6’ from a fireplace.
  • A notice describing the do’s and don’ts left on the kitchen counter.
  • A notice at all entry doors reminding people to keep the doors closed.
  • Short term tests should be between 48 and 72 hours long.

EPA guidelines are not regulated by the state of MN.

Unless you are certain about who is doing your radon test, you should ask for a copy of their certification and a document verifying the monitor has been calibrated within the last year. An electronic tamper-proof monitor is the best way to assure accurate test results.

A faulty test puts the home’s occupants at high risk.

Doug Hastings
MN Home Inspector, Minneapolis & St. Paul
ASHI Certified Inspector, ACI
Kaplan University, Home Inspection Lead Instructor

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Controlling Radon Gas

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.

Doug Hastings
MN Home Inspector, Minneapolis & St. Paul
ASHI Certified Inspector, ACI
Kaplan University, Home Inspection Lead Instructor

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