High Radon Test?
Mitigation is a term used to describe the methods to reduce radon gas levels in your home. Health Canada recommends this procedure is performed by a C-NRPP certified professional to ensure all proper protocols are followed.
Mitigation begins with an on-site consultation to determine the best radon reduction system for your home. Radon entry points are identified and sealed if possible. The most effective and reliable radon reduction technique is called sub-slab depressurization (also called active soil depressurization). This is also the most common technique used by C-NRPP certified professionals. We identify combustion appliances with potential downdrafting (woodstove, oil-fired furnace with chimney) and ensure that they have a make-up fresh air duct in place (if not we install ducting). This is critical for reducing the possibility of carbon monoxide entering the home.
Next a diagnostic Pressure Field Extension Test is conducted. This procedure uses a shopvac to determine how easily air can be drawn from a test hole to a monitoring hole under the concrete floor. This information determines the fan size and number of suction points needed for the radon reduction system design. Typically one radon fan and suction point is all that is required. In unusual cases where clay soil is under the basement slab or inaccessible crawlspaces are encountered, extra suction points or fans may be required.
A sub-slab depressurization system requires installing a 4″ PVC pipe through the concrete slab and attaching a fan that runs continuously to draw radon gas from below the slab before it can enter the home. The pipe exhausts radon through the top of the foundation wall where it is quickly diluted outdoors. This system also reverses the air pressure difference between the soil and the house which reduces the amount of radon that is drawn into the home through entry points in the foundation and floor. The soil in a crawlspace or home with a dirt floor basement can be exhausted using a similar technique called active sub-membrane depressurization. Polyethylene matting is installed over perforated PVC piping and made air tight by securing the matting to the foundation walls with screws, battens and caulking. The PVC piping is attached to a radon fan and vented outdoors.
The radon reduction strategy is discussed and approved by the homeowner prior to proceeding with system installation. Our goal is to reduce radon levels below 100 Bq/m3.
If home ventilation is required to further reduce radon levels or to provide indoor air quality control, Heat Recovery Ventilation (HRV) systems are designed and installed by our certified Residential Mechanical Ventilation technicians. We also balance and clean HRV’s as part of our normal mitigation service. A short-term 72 hour home test is started 12 hours after system is installed to confirm the radon levels have been reduced and a Post Mitigation Report is given to the client. Health Canada recommends a 91 day long-term radon test is performed during the next home heating months to verify the radon reduction system performance.
Mitigation systems offer additional benefits beyond reducing radon. Radon fans exhaust moisture from the house resulting in reducing mold and mildew.