Radon Mitigation - Home Owner - Lessons Learned

We had noticed homes in our area with large white pipes run up the side.  Some 
looked like downspouts, but extended up above the gutter.  I asked around and was 
told that was for Radon mitigation.  I did some research and learned that many 
homes cannot be sold until testing has proven Radon levels are low enough or 
mitigation has been done to achieve safe levels.  Radon gas occurs in Colorado 
soil in many locations.  This odorless gas can seep in through basements and cause 
Cancer. 	http://www.epa.gov/radon
A friend described his mitigation steps and told me about the contractor that 
performed it.  This contractor also trains other contractors.

Before hiring the contractor, we followed their advice and bought an inexpensive 
sampling kit.  We followed the kit's instructions to leave the small metal can 
open in the basement for the few days then seal it up and mail it to their 
laboratory.  The resulting 12.4 pCi/l reading was high enough to be unsafe.  We 
hired that same contractor.

Crawl Space Preparation:
* Remove all stored items
* Remove all construction debris (e.g.: sharp cornered rocks and concrete chunks, 
nails and metal scraps).  Yes, this included empty soda cans.
* Provide ample supply of flattened corrugated cardboard boxes to protect the 
underside of the tough sealing membrane.
Provide good quality landscaping cloth.  This can be used to wrap the perforated 
gas collection ducting and help filter out soil dust that could, over the years, 
start to clog the ducting.

Sump Pump Pit:
We have never had any flooding.  They glued a little window into the Sump Pump Pit 
Cover and then sealed the Cover in place.  In a rainy period, we can shine a light 
into the little window and assure ourselves that there is no water accumulation.  
The continuous Radon venting helps prevent the water accumulation.

Basement Floor:
The primary gas collection is through the basement floor.  They drilled a hole 
through the concrete, removed soil to create the required open space under the 
floor.  They sealed in a vent pipe connected to the Radon ventilation system.  In 
our house the vent pipe is routed through the crawl space and out through the 
garage, through the attic and out a roof vent.  The ducting is 4.5 inch outside 
diameter PVC drain waste and vent pipe. 

Crawl Space what to expect:
4-5 inch diameter corrugated and perforated flexible plastic ducting will be 
placed around the periphery and plumbed in to the Radon venting system.

A very tough plastic sealing membrane will be sealed to the concrete foundation 
with construction adhesive.

Ventilation is recommended, initially, because the adhesive curing process does 
emit some fumes.  The curing process is much shorter above 50 degrees F.

The manometer indicates if the system is maintaining the required vacuum under our 
house.  Loss of this pressure differential would indicate pump failure or leakage 
in the sealing membrane and time to call the contractor.

Crawl Space Continuing Care:
Since we use our crawl space extensively for storage, we keep adding any larger 
flattened corrugated boxes we receive (all staples removed!) on top of the sealing 
membrane.  Of course we are careful about footwear as we crawl or duck walk around 
in there.

Exhaust Vent:
The collected gas is vented above the roof line to prevent its reentering the 
home.  Some homes have it vented at the side of the house through an 'up spout'.  
In our case, we selected the option to have the ducting run through the garage, 
trough the attic and out through a roof vent.

Exhaust Fan:
The Exhaust Fan is located in the attic.  It is wired with a master switch mounted 
in the garage ceiling.  Our fan is quieter and is a higher quality than many.  It 
cannot be heard from any of the bedrooms nor the outside.  A soft hum can 
sometimes be heard, however, from the Bedroom closet that has an attic trapdoor 
and also may be heard from the hallway.  After a rainy period, the fan works 
harder to pump out the added moisture and is noisier for a while.  When dryer 
weather returns, it quiets back down.  I wonder if it is realistic to mount it to 
the attic trusses with vibration isolators so it could not be heard at all?  I do 
not think anyone else has ever noticed any sound from our Radon mitigation 
system.  The transverse duct in the attic is insulated to prevent any water vapor 
in it from freezing.

Results:
The Radon Mitigation process took part of a day.  After the Radon Mitigation 
process, we used another test kit.  Its results were 1.3 pCi/l.
The Radon level reading before Mitigation was 12.4 pCi/l.
Since the mitigation (18-Dec-2006), the readings have remained 1.3 and 
occasionally 1.4 throughout these winter months.
Two and half years after the mitigation, the readings with our long-term monitor 
remain in the 1.2 - 1.4 range and vacuum pressure remains at 0.7.
We are now breathing easy and are confident in using our finished basement for 
family guests!