4. 10 ways to help Remediate Radon Gas From your Home
The purpose of this blog is to help you become familiar with some of the methods that you, the homeowner, can take to help reduce the influx of radon gas into your home. These steps are not complicated nor are they overly expensive. If you have a definite concern about radon in your home, it is highly recommended that you have it tested. You can pick up a radon test kit from your local hardware store, or you can have me test your home for you. If the results show that remediation or reduction is recommended, following these ten steps can reduce your homes radon level. After steps have been taken to reduce the radon entry, have it tested again to determine how much the levels have been lowered. These ten steps are for your information purposes only, and further evaluation by a radon remediation professional is recommended.
Step 1: Sealing all cracks along the basement perimeter walls and any place that pipes or fixtures penetrate the concrete. These include; chimney, floor drain, main plumbing pipe entry point, main electrical entry point, around posts through concrete, cracks in the concrete floor, sump pump cover etc.
Step 2: Installing special traps in the basement floor drains that allow water to drain but prevent radon gas from entering the basement. These are commonly called a backflow restrictor or a one-way valve.
Step 3: Installing a sealed cover over your sump pump; Usually, the sump pump has two entry points from the footing drain and sometimes one entry point from an under the slab drain. These drains will collect radon gases from the ground if present. You may need to look for or configure your own sump pump cover sealing lid or cover that also seals around the exit pipe and power cord as well.
Step 4: Completely covering a dirt floor crawlspace with six mil poly plastic; This may be a daunting task at the best of times. The ground surface of the crawlspace should be completely covered with a six-mill poly vapour retarder, sealed at the edges to the wall and around all piping and other penetrations. This will need to be laid loosely so as you move around in the process; you will lessen the possibility of pulling it away from the wall that you have just sealed to. All overlapping seams should be a minimum of 12 inches overlap and preferably caulked at the seam mid-point.
Step 5: Passive slab ventilation system: A passive slab ventilation system is the installation of a 3-or 4-inch PVC pipe which begins under the concrete slab or a crawlspace area that has the vapour retarder or radon barrier placed over the remediation pipe. This will de-pressurize the area under a concrete slab, vapour barrier, sump pit, or other system or area that requires radon remediation. This PVC pipe is run up through the building (usually within the wall system), and the exit point is in a suitable location through the roof. The vertical portion of the pipe acts as a chimney and induces draft as it passes through the warmth of the building. Depending on the area that needs the remediation, the under-slab portion of this pipe is usually perforated, and with a “T” so it can extend at least 5 feet on either side. The under-slab portion is embedded in the under-slab aggregate which forms a gas permeable material through which the radon gas passes easily. Installing this pipe under your basement floor will require you to break up some concrete and do a little digging. It is important to note here that if you are planning any major renovation, such as converting an unfinished basement area into living space, this should be done first. Careful planning here is key. Because major renovations can change the level of radon in any home, always test again after work is completed.
Step 6: Passive to mechanical ventilation; Passive slab ventilation system may work in some cases where the radon levels are somewhat lower or the area to be remediated is small, and further testing reveals that this system is working as intended. But for the most effective and reliable radon reduction, an active reduction system with a power vent fan that runs continuously to draw the radon gas from below the home and expel it to the outdoors where it is quickly diluted. This is known as an active slab depressurization system. Because this system is power vented by a continuously running fan, it can be vented through a suitable location on the roof, or at a location along the exterior wall system, provided the exit port is 10 feet away from any window or door and 2 feet above. Ideally, for a roof vented system, the fan should be mounted in the attic space. The portion of the PVC vent pipe above the fan will be slightly pressurized, and it is important to ensure that there are no leaks within this portion of the pipe. If the fan is mounted in the basement then most of the pipe will be in a pressurized condition, it is equally important to ensure that all joints are sealed tight with no leaks. Any leaking in this pipe system will result in radon gas spilling into your living space. With any active depressurization system installed in your home, it is recommended to make sure that its operation does not cause a back-drafting condition from combustion appliances such as your furnace, water heater, fireplace, or wood stove. Back drafting can happen when a room with a combustion appliance is depressurized so much that smoke and combustion gases are reversed and pulled into the home instead of venting through the existing chimney to the outdoors. For this type of system, and the passive system you should consult with a qualified radon remediation contractor.
Step 7: Reduce the are pressure; In my second blog I talked about the problems with negative air pressure in your home, commonly caused by the stack effect and any appliance that exhausts air to the outside. This negative pressure situation will also encourage radon gas and other earthly airborne smells into the basement for further distribution throughout your home. You can check this problem yourself with a smoke pencil. To do this, close all windows and doors and turn on several fans, such as a bathroom fan, the fan over the stove, and perhaps the clothes dryer. This will ensure that air is leaving the home. With a smoke pencil, (get at hardware store) go into the basement and slowly move it across any cracks in the floor, your sump pit if you have one, and any area where you think that air could be seeping through. You will notice a rapid change in the configuration of the smoke coming off the pencil. These are areas where radon gas will be entering. This is an indication of negative air pressure in your home; you will need to introduce more fresh air from outside to replace the air that the fans and the stack effect of your home is exhausting. Check your furnace room to see if there is a combustion air vent ( usually a black plastic tube) which may be sealed off because high-efficiency appliances have been installed, and this combustion air vent is no longer necessary. Or perhaps you can have someone install one for you. This only needs to be a 4-inch insulated corrugated plastic pipe, (tube) connected to a screened intake vent from the outside through the wall. This pipe should run at least 8 feet across the ceiling, to warm the incoming air up a bit, and it should terminate in a small metal container or small pan to catch any condensation that may develop. Consult with a qualified HVAC contractor for further advice or to install an air balancing vent.
Step 8: Install an HRV; A Heat Recovery Ventilator is a wonderful way to have a continuous supply of fresh air brought into your home which is heated from the air that is leaving your home. The intake port of the HRV can be in the basement to exhaust radon contaminated air. You can have them set up, so they run continuously, or on a timer, supplying fresh air into your circulating furnace system, or supplying fresh air to certain points throughout your home. They will help in neutralizing the difference in air pressure between the outside and inside. And they will also help to reduce the radon levels within your home. There is a new product that is just becoming available; it is a radon detector installed within the air system of the HRV. It monitors the air flowing through the HRV, and when it detects an unacceptable level of radon gas within the airflow, the HRV will speed up dramatically to increase the air changes per hour until the sensor determines that the radon levels have been lowered to a safe concentration. The HRV will then resume its normal operation. They are not a DIY project and should be done by a qualified heating and ventilation contractor. I have had one in my home for the past ten years and it is running pretty well steady, 24/7. I usually shut it down once a year and remove the air to air exchanger and give it a rinse with the hose. Highly recommended.
Step 9: Seal tops of concrete blocks with concrete; This may or may not be a type of wall system that is found in the average home. They are usually found in condominium or apartment-style housing, and they are normally firewall barriers between units. Concrete block walls or CMUs (concrete masonry units) are hollow and provide an open path from the ground/footing to the ceiling or roof system. The top of this wall may be difficult to get to, but if there is any section that is open, they can be stuffed with newspaper as a stopper, down about 3 inches from the top and filled with concrete to seal them off.
Step 10: Contact a qualified HVAC contractor for consultation on temporarily blocking the furnace return air vent from the basement. By code, as referring to the “building codes,” they state that you must have a return air vent on each floor of your home. For good reason, it pulls the cold air off the floor, heats it up and re-circulates it throughout your home. But, after testing for radon gas, and the results indicate a high level, and remediation is recommended. You may need some time to get your finances together or complete some other project. You can take some temporary measures to ventilate your basement and possibly block the basement return air vent so there will be less radon gas from the basement sucked into the furnace return air vent and distributed throughout the remainder of the house. This should only be done or not done on the recommendation of a qualified HVAC contractor.