Radon vent pipe clearances explained – a best home inspection – home improvement services average gas bill in texas

When it comes to radon vent pipe clearances it can be confusing what is and what’s not allowed, what’s safe and what is not. Looking at radon mitigation systems in central new york you will see a wide range of installation methods including the location of radon vent pipes. Very often radon system installations do not follow the EPA or similar radon mitigation standards. There are several reasons for this confusion including:

Some states are just beginning to look at implementing codes and educating code enforcement officers for radon mitigation including new york state. Monthly fuel cost calculator uk the EPA and other guidelines somewhat follow the standard codes for plumbing vent pipes which generally are vented above the buildings roof. New york state just raised plumbing vent pipe code from 12 inches to 18 inches above the roof and at least 10 feet horizontal distance from any opening to the building i.E.


Window or fresh air intake. The EPA radon mitigation standards are pretty general designed to cover a wide range of building situations. Radon vent pipe clearances – example

In following scenario, following the EPA standards it would be fine for a small single story house 1.) to be vented above the roof line as close to the ridge as possible, 2.) terminating at least 10 feet above the ground. This would be considered safe even if there may be a high rise building right next door with windows and balconies many stories high with the closest window only 10 feet and 1 inch horizontal distance away from the radon vent termination and with many more windows above that. This scenario would meet the EPA safety standard for the high rise occupants, figuring that the radon laden air would dilute to a negligible amount after traveling less than 10 feet. Practical application of safe radon vent pipe clearances

So practically speaking, if there are no specific codes that require otherwise, in the above high rise scenario those same clearances should be perfectly safe to apply regarding your own home. As long as you meet the safety distances from openings to the building and direct the radon gas away from the home so as not to cause moisture damage, in some situations it may be preferred not to vent above the roof line.

Practical example: lets say a radon system is located on downwind gable end of a 2 level home and the height of the roof ridge is 35 feet above grade and there are no windows at all on the entire wall. By the way this is a fairly common situation I run into. Say there is an exterior chimney on the center of that wall and you want to run the radon vent pipe on the rear side of the chimney so it is not seen from the road. It should be “safe” to terminate the radon pipe 15 or 20 feet above the ground (which exceeds the 10 foot minimum height standard). It is also well over 10 feet horizontal distance from any windows or vents to the sides or above including any soffit vents that may be present. Even though the radon pipe does not extend “above the roof as close to the ridge as possible” it discharges the radon gas in a safe way, while reducing the vent height by 15 to 20 feet. In this example, even though it does not technically adhere to the EPA radon mitigation standards, it does adhere to the heart of the safety issue. It also has the benefit of shorter vent height which will improve the performance of the system and make it easier and safer to maintain and service, verses running the pipe another 15 or 20 feet to meet the letter of the EPA standard.

In this photo to the left you can see a radon vent pipe that terminates safely about 13 feet above the ground and greater than 10 feet horizontal and 2 feet above the closest window. The top of the vent is angled at 45 degrees to the moist air does not cause moisture damage or mildew stains on the siding. This homeowner preferred this installation verses running the vent up the soffit, around the gutter and above the roof.

Below are some pros and cons pertaining to radon vent pipe clearances explained that should help you in determining what might be best for your specific situation. I like to weigh out all the options, talk it over with the homeowner and decide what will work best for their needs. Advantages of shorter radon vent pipes when safely installed:

Including contractors who say they strictly adhere to the EPA mitigation standards of practice it is very rare that any radon mitigation contractor will run the vent pipe up the center of a gable wall in order to terminate the vent pipe above the roof as close to the ridge as possible – as per the EPA standards. I explain the practical and safe application or radon vent pipe clearances and if that is what people want, I will be happy to do that. Cost savings gas vs electric dryer they may want to be extra safe, but at the same time I explain it will be more difficult to service, less aesthetically pleasing, and sometimes may cost more.

Side wall venting. Many gas appliances vent through side walls now instead of chimneys. One of the newest fans designed specifically for radon mitigation vents directly through the side wall similar to a dryer vent, using an aspiration hood to mix and disperse the radon gas; it follows the same clearances as high efficiency gas fired heating appliances that also vent through side walls, they are allowed to at least 4 feet directly below a window opening. Additional clearances to doors and vents also apply similarly to the gas appliance sidewall exhaust vents.

Good question, I get asked this a lot. Water will not harm most good quality “radon” fans. I tell my customers, you could dump a 5 gallon bucket of water down the pipe with the fan running and it would not harm the fan. Cost of trip gas mileage with a 4 inch pipe diameter open to the sky, in a torrential downpour I doubt you would ever get as much as a quart of water in the pipe and remember the air is blowing out quite forcefully in most systems so light rain would not even enter. The fans have sealed bearings and are rated for high moisture environments. Some radon systems can pull upwards of several gallons of water moisture from the soil each day, depending on the moisture level in the soil and size of fan; this makes for a very wet environment inside the radon fan and vent piping. However proper installation is important whether you have a rain cap or not. If the vent pipe is properly installed, meaning the proper materials used (typically schedule 40 PVC pipe), all the pipe joints properly sealed with PVC primer and glue, and all the vent pipes back pitched so that any condensation build up or water from the top of the vent pipe will all drain back down the vent through the fan and into the ground, then there are generally no problems. Problems arise when pipes are not properly pitched, then the water can pool or collect or completely block the flow of air if there is a trap built into the vent pipe. The reason most of my systems do not include caps is that the cheap caps block the air flow quite a bit and can reduce the effectiveness of the mitigation. I’ve see some systems that did not get the radon below 4.0 pci/L and by just removing the rain cap the radon levels dropped significantly. Good quality low restriction caps cost about $20 to $35 and most people don’t want to pay it. I offer screened rain caps as an option. In my opining the best reason for a cap is to keep critters out of the pipe for low air flow situations or in case the power gets turned off. I have taken quite a few dead birds and squirrels out of radon fan housings. So I usually just install a stainless steel screened cap, that is open to the rain.

The assumption that radon is a heavy gas may be true, however the wind is much more of an issue. If you have 10 or more feet from the termination of the vent pipe to where the window opens, you should be fairly safe. It is best to vent above the roof if possible and above windows if possible. In some areas there are radon mitigation standards that must be adhered to in order to be acceptable. It sounds like you are pretty close to the acceptable distance, if you are not sure you could check with your local building code officer, they may or may not be able to help, many are not familiar with radon mitigation system standards.

You could also do your own testing to make sure; to best perform the testing you would need an electronic radon monitor (about $130), that way you could do multiple tests and get instant testing results. Test that room with the window open and closed in various weather conditions, and see if there is any raised radon levels with he window open as compared to being closed. Hope that helps.

We recently purchased a home and had a radon system installed shortly after taking ownership of the property. I was not home at the time of install, and communicated with the installers via phone. Price of gas by state 2012 we decided that the best place for the system was the basement wall that has exhaust for the furnace and piping for the A/C unit, as the masonry chimney for the upstairs fireplace was on this wall as well. The piping was run along side the chimney to just above the roof line. It is a cape cod with a very pitched roof, and the pipe runs up the wall, along the chimney (which is positioned at the center of wall) to highest point at the top of the roof line. I had two questions for the installers. 1.) they used down-spouting instead of PVC and said that was acceptable. I have never seen down-spouting used in my area (PA) before. And 2.) there is a second story window that is very close to the chimney and thus close to the pipe running up the side of the house. The down-spouting actually almost touches the chimney on the left side and does touch the window trim on the right. I asked for aesthetic purposes if we could run the pipe from the system to just below the second story window (which is greater than 10ft in height) and then put an elbow (90 decrees or so) so that the vent pipe would be positioned away from the house. This would look 100 times better as the pipe would naturally end underneath the window instead of running right up against on the trim. I was told that was not an option. Is there any danger if I cut the down-spouting off under the window and put an elbow or extension so it points out away from the house?

I can think of three reasons right off the bat. 1) safety; 2) to avoid confusion; 3) plumbing vents are for plumbing systems and radon vents are for radon systems, those two should not be combined for a multitude of potential reasons. How much does gas cost per mile for one thing the plumbing vent most often, pulls air “down” into and all through the house to assist the water flow when draining. If you had an open trap for some reason the radon gas, along with sewer gas could be pulled into the homes living area. IF it is tied into the plumbing pipe most people would assume it is a plumbing drain and or plumbing vent pipe. I have seen a few times where people mistook radon vent pipes for plumbing pipes and added a new sink or drain that tied into the radon pipe; this is a big problem, now you are using the radon vent pipe for a plumbing drain, the waste water just drains into the ground below the slab at the radon suction point, and depending where it ties in, it will also drain right through the radon fan, which isn’t a big deal if it is just water, but is a big deal if it contains say toilet paper or more.

Hi chris, I can see where you are coming from, but sub-slab depressurization has been proven as the best way to mitigate “most” homes for a reasonable cost. After much research, trial and error sub-slab depressurization is what is what the EPA, other state radon agencies, many governments of other countries. It is the go to method of radon mitigation in homes for engineering and contracting companies that install residential radon mitigation systems. I would refer you to the details and methods of performing sub-slab depressurization which is off the topic of this thread. A couple of main points, the soil under the slab most homes is contained within the footers which corral the soil gasses below the slab so most of the suction is contained within the footer boundary. Even in dense soil one suction point is sufficient to draw air from the entire footprint of the slab if the fan is sized properly. In some cases I have sealed the floor and installed fresh air exchange to reduce the radon but it is more expensive, and less effective generally and only used when the concrete floor is poured over bedrock and no chance of air movement below the floor, or when there is a gravel or dirt floor basement or crawl space – but even in that case it will only work if the radon level is fairly low to start with.