All new houses in Minnesota are required to have radon removal system installed into each housing unit. Various designs are allowed by the state some with collection tanks (sump baskets) and some with out. The state haves mandated the following items that must be done.
Install a perpetrated drain pipe around the interior foundation wall with a minimum 4 inches of course fill not sand allowing water and radon gas to migrate to the collection center.
Install a continuous 6-mill poly vapor barrier under the entire concrete floor
Seal all penetrations coming through the concrete floor pipes block wall to floor edges etc…
Seal the collection tank only leaving 2 sealed pipes coming out 1 for removal of underground water; the 2nd is for the removal of radon gas.
Install a 3” vent pipe vertically from the collection area passing through the house and venting above the roofline.
Let’s look at the actual working of installation of said law, install a 6-mill poly on the dirt before you lay out rebar or wire mess. The steel being inserted onto the concrete keeps 1 the concrete floor from cracking, separating, shifting, or shrinking 2. It reinforces the floor incase the dirt under the floor settles. Rebar comes 1/2” x 20 feet long and is heave and flops around like a fish out of water. You will have a number of holes in the poly liner before the rebar is laid out and tied together. If you use wire mesh this comes in rolls of 5 foot wide x 20 inches diameter about 100 foot per roll, when you unroll this little monster it acts like a slinky wanting to recoil the only way to straighten it out is to flip it over and re-bending it by hand. Resolutes at each end of 1 row you have just punchered the poly membrane 10-12 time.
The code says you must take a new piece of poly and over lap the hole by 1’ on all sides no a basement of 22 x 38 (24’ x 40’ House) a minimum of 120 holes. Now its time to pour the concrete (concrete is a mix of sand small rock, portland and water) you can install it 2 ways; wheel barrow it to the location and dump it, or you can pump it in with a large pump truck add $800.00 to the bill. Did you fix all the holes the wheelbarrow made and the guys pouring the floor, well that’s a radon leak.
After the floor has harden up you walk around the floor sealing all joints between the floor and wall and floor and any protrusions through the floor. About 1 –2 years after the house is done because you chose not to install reinforcing in the floor your floor have at least 3 and up to 10 large cracks big enough to put a tooth pick in it. Oh that’s right you laid carpet on the floor you’ll never see the cracks where the radon is getting in the living space and where Johnny and Amber likes to play and sleep on the floor.
Let’s look at the collection and exhaust system. Remember in this collection area there is standing water as well as an electric pump to pump out the ground water. Facts undisputed radon gas is heavier than air. So radon gas builds up in the collection tank it never leaves the tank and the vent pipe because it’s to heavy now the ground water comes into the collection tank what happens to the radon gas it rises and falls according to water level in the collection tank. In fact the radon gas in the tank will increase in the parts per million making it more toxic I feel bad for the plumber that must change out the sump pump, he has to get down in there to fix the problem. Note when the radon gas moves up into the exhaust vent, it’s now looking for an easier way out, that crack in the floor has a lot less pressure and a bigger area to expand into. Solve the problem (the states view point) Just add a fan and blow the radon gas out of the house. The problem is it does matter how small or big the fan is if there is no air coming in to the drainage system you will never blow any air up the pipe, let alone radon gas which is heavier than air. The state say’s all you need is a small fan, may be rounding about 10 minutes per hour. 1st the state don’t have a clue how much air in cubic feet of air per minute or per hour is going to ventilate the radon gas from below the floor to solve the problem.
Let’s say it’s possible to vent this gas out of the house, well you don’t want to see the pipe from the front side of the house, let’s vent it on the back side of the roof, great or is it. On the backside of the house are the following screened, porch, deck, sand box, swing set, and other toys to play with. Radon gas is heavier than air it’s pumped on to your roof and taken away with prevailing winds and if there is no wind it rolls of the roof and into your backyard. Looking down at your house from the sky we see the following a pipe sticking out of the roof with no cover over it and you can not cover it by law, that means when it rains water goes down the pipe so what it goes into a sump tank if water can go down so can cold air in the winter time, when this happens it will freeze the surface water in the sump tank or the ground in the collection area and if there fan is installed water will be dripping and getting the fan soaking wet. Well we no longer can use a cheap fan we must put in a stainless steel fan with a concealed shaft with a water bypass system in it. ”$” Now to make this system work we must bring in air into the drainage system. We cannot take inside air just for the fact if the power went out the radon gas has an easy way back into the house. We can us outside air it 20 below or greater in the wintertime freezing the sub soil under your floor and leaving the opportunity to heave your footing.
The only air available to you is in the new law that no one has thought about, you must have an exhaust fan run 15-20 minutes per hour. Blow this air under you floor and the radon fan pumps the radon gas filled air out of your house. Now you are running 2 electric fans and praying the power never goes out.
Or Just excavate and other 24” lower and install an angled concrete slab 4” with rebar cover with epoxy paint than build on top of it for your house the radon gas will come in contact with the lower slab and slide upward to the surface level on what ever side you choose to bring it to the surface