• Radon gas is constantly released by each soil granule into soil air.
  
  
• Air pressures within the home pull soil air (containing radon gas) from below the foundation into living spaces.

  This results naturally as warm air rising upward in a home creates a somewhat consistent vacuum in the lower regions.
  
  

  Once in the home, radon gas is diluted somewhat by fresh air that is also naturally pulled in around windows and doors.

  The radon gas is then distributed through the home by heating/cooling blower activity or simple mixing of air.

Simple soil is the most common source yet radon gas can also result from certain crushed stones, stone formations or other sources under a home that allow radon gas to move freely.

• Systems extend a slight vacuum under the home to pull this air away from living spaces and direct it towards the outside.
  
  
• Our experience in over 10,000 systems agrees with EPA studies..... When installed carefully, concentrations are typically reduced by 80-99%.
  

• Pipe must extend upward (typically to the roof) for discharging radon safely away from the home.
  
  
• Fan must be located outside occupied spaces.

Vacuum strength needs are dictated by what’s under the home.

Air Volume needs depend on soil cavities (size or leakage to building or outside).

Radon enters from under all areas with potency usually based upon area size.

Treating 100% of ground contact areas (including garages) will maximize reductions.

A barrier between soil and living spaces is needed for effectiveness in creating a slight vacuum under the home. However: A substantial leakage area will exist undetectable to the eye regardless of meticulous sealing efforts.
Systems are still effective since soil air is pulled away from living spaces. Sealing of accessible, large openings to soil is typically a system component.

There is a minor energy penalty when air is pulled out of the home but major renovations to seal small cracks are not justified monetarily. Appropriate fan sizing aids this concern. For small sealed slabs, a very small fan can also be effective which maximizes all aspects of energy efficiency.

Sealing Items & Materials:
Sump cover: . . . . . . . . . . . . . . Customized from clear, non-breakable plastic.
Accessible floor-wall joint: Urethane caulking.
Tiny “hair line” cracks: . . . . .Typically not cost effective or meaningful.
Misc. cracks & openings: . . Caulk, expanding foam, mortar (as needed).
Drains that go to soil: . . . . . Air Traps. (a float prevents upward air flow.)
Open Earth: . . . . . . . . . . . . . . Poly sheeting over open earth and secured/sealed to walls.

DISCUSSION OF SEALING ALONE: .... “EPA does not recommend the use of sealing alone to reduce radon because, by itself, sealing has not been shown to lower radon levels significantly or consistently.”

Always unpredictable, sealing alone may sometimes reduce levels 10-50%. However, often little effect is seen (even if all gaps and openings are accessible to seal).

Responsible Sump Covers:

• Visual access to conditions in pit
• Removable port for arm access
• Anchored and sealed air tight
• Labeled
• Can hold the weight of an adult

These covers require a saw to gain access
when sump fails and flooding is immanent.

Other poor examples

ROUTINELY CHECK THAT FAN IS OPERATING. Because fans are so quiet, a pressure gauge is required on the piping for easy verification that the fan is operating. Check routinely (such as quarterly).

RETEST: After installation, insure a retest with a continuous monitor is performed where hourly readings can help identify problems.

Thereafter: You may test for verification at any time. The USEPA recommends retesting every two years to insure continued effectiveness. Home test kits are an inexpensive and effective test for this purpose.