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We were very impressed with the overall quality and expertise of Radon Home Measurement & Mitigation. They were very careful with the placement of the fan and went above and beyond our expectations. I would highly recommend them to anyone looking for a radon system in their home.
David & Cristy
Fort Collins, CO

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Quest for Quality

Learn more about the founder of Radon Home Measurement & Mitigation
Learn more about the founder and President of R.H.M.M.
Dr. Leo Moorman Ph.D.



The Road Towards Radon Mitigation Systems of Higher Quality

Some time ago a request on the Radon Professionals List was made for some place to have a repository of photo’s of bad systems or violations of standards. Some examples have been discussed since then via this list. Although really bad systems are easily recognizable by most on the list, I would like to discuss a few systems that might be reasonable but can be done better. I would like to encourage with this letter the recognition of installing higher quality systems.

I take “higher quality” to mean that the system improves at least one or more of the following three factors compared to a reference system (often the existing system). These factors are: (a) a system with a higher efficiency of radon removal, (b) a system that has more energy efficiency or causes less energy wasted, (c) a system that has a lower noise burden on critical places where people live, whether inside or outside.

This letter is about two systems I encountered recently. The first system (A) did not reduce the radon concentration below 4.0 pCi/L, so it did not pass the minimum EPA criterion for the buyer. The second passed this criterion, but the noise level was too high for the current home owner.
Both systems were eventually refurbished into satisfactory and (almost) EPA compliant systems.

It is not my intention in this letter to give the competition a bad rep and am not soliciting to identify the companies that installed them, but I simply want to point out a few practical issues that we encountered and that can be improved upon in future installations by certified individuals. There were also a few surprises in solving the issues.

The first house was a new home construction which had a system that did not bring the radon level down below 4.0 pCi/L. It had a appropriate radon system with a pipe attached from below the slab in the basement following EPA standards and a proper radon fan in the attic of the garage but the crawl space was left open dirt with a normal ventilator (“booster”) fan set before one of the vents.
The booster fan shown in the photo with flexible duct work was found to be installed in a corner of the crawl space plugged in and continuously venting the crawl space drawing air in through a different vent.

  1. System had no radon or installer's label (Not EPA).
  2. Vent fan is not listed as a radon fan (Not EPA).
  3. Material of vent duct is not approved material (Not EPA).
  4. Fan is placed in crawl space under living area and not above grade level as required (Not EPA).
  5. System was permanently hooked up to an extension cord with plug and connector lying on sandy bottom of crawl space (Electrical code/EPA violation).

home made radon mitigation

In the next photograph the open design is shown which could be danger if children like to play in the crawl space. (Yes, I have heard home owners telling me their children like to play in the crawl space and were very happy with the white clean plastic barrier I installed and that the system took care of the radon problem in that space too.)

home made radon mitigation

To solve the problem we placed a draintile pipe with radon barrier material above it covering the entire crawl space floor, with enough slack so that the barrier material can adjust sufficiently as it deflates. Barrier material is completely caulked against the foundation wall as it was installed following EPA standards.
The resulting new system was able to bring radon level down to below 4.0 pCi/L without any problems.

Higher quality points (a) and (b) are improved with these changes, point (c) is not changed with this.


When the second system was looked at in detail there were a few more things to improve, than what the original complaint was. Although the EPA guidelines state that systems do not have to be upgraded to EPA standards, the home owner wanted to upgrade the system on most aspects. According to the age of the fan the system must have been installed when the previous buyer bought this house in the second half of the year 2000.

I was called by current home owner because the system made so much noise that the he could not sleep at night and was considering turning off the system at night.

At first glance, nothing obvious seems wrong with it. Here is the exterior view of the system I found:


Further investigation shows:

The noise that the home owner complained about is caused by:

1) Fan has discharge point at the exact point where home owners bed is on second floor in master bedroom. Measured through the wall when asleep the home owners head is within 20 inches from the discharges point shown in photograph, yet on the inside of the wall. (See picture above for the discharge point)

2) All downspout pipes are installed with the upper part into the lower part (top-into-bottom). This causes extra friction and air loss at each junction/connection which were not caulked. The extra friction causes extra metallic noises echoing through downspout.

[Note: A recent discussion after this letter first posted has given some arguments in favor of this type of top-into-bottom installation when using downspout material, although others prefer the bottom-into-top downspout installation.]

3) No caulk is used at transition point PVC to downspout. This causes a rush of air (and radon) loss with similar noise at the base of downspout. The other side of the wall has a couch in living area where noise from this side can be heard. Mold in home made radon mitigation

4) Two windows of master bedroom within 10 feet of discharge point that is not 2 feet above it.
(Does not meet EPA standards)

5) Fan is 5 years old and does not appear to be causing an excessive vibration problem, but all brackets are solidly screwed into wall with long screws, eliminating the effectiveness of the bubble wrap vibration isolation padding that is used. This solid connection as well as the solid connections along downspout are a cause of transfer of vibration into wall and noise on inside. Improvement of this is possible. Mold in home made radon mitigation

6) Interior part of the system uses self made PVC connectors. These are made from PVC, caulk and cardboard. These cause large noise in crawl space which because it is placed directly under the return duct work causes the metallic duct work to pick this noise up via its internal resonances and transport it into living room directly above.

Other remarks about this system are:

7) System has no label. Thus it is not known who installed it, nor identifying any part of it as a radon system.

8) There is a soffit vent straight above the discharge downspout point within 10 feet. Soffit vents are designed to be natural entry ways for outside air, thus potential of radon drawn into attic can be a concern. Mold in home made radon mitigation


9) When electric plastic hard PVC conduit was dis-assembled from fan it immediately broke off from the box as shown below. There was no force involved to the extent that this must have been cracked before. Mold in home made radon mitigation

10) Moisture protected electric box had two holes drilled in back that were used as screw holes to attach box against wall. These holes were not caulked. These are potential entryways for moisture. In addition, no caulk was used on back of box to protect water infiltration into wall from between box and wall.

11) Electric box when first opened was found with a substantial pile of small wood chips in the bottom. These wood chips appear to have been brought in by insects (ants?) through the existing openings pointed out in item 10) above. These dry wood chips form a fire hazard if piled up high enough to reach the contacts. Mold in home made radon mitigation


12) Without the benefit of a moisture capture and discharge system above the fan to the outside moisture drained through the fan . Consequently a significant colorization red and black seems to signify mold built up on the inside of the pipe (To be fair, no mold test was done to verify this.). This same built up was visible in the pipe to downspout adapter that was shown in 3) located above the fan. Mold in home made radon mitigation


13) Pipe from radon extraction cavity under slab into crawl space was using part of the already small crawl space entrance. The crawl space is only 3 feet high, with duct work and plumbing pipes hanging below the floor joists immediately behind entrance as well as an upward sloping dirt floor, making it a very cramped entry. There were several opportunities to install this pipe differently although it would have taken somewhat more material and time to accomplish by the original mitigators. This does not follow EPA standards and is considered a bad practice.
However this aspect of the system was not changed in the end. The yellow radon identification label was placed by us, not by the original installer.
Mold in home made radon mitigation


14) Inside crawlspace the connection pipes are choked down with self made PVC pipe Tee’s in two locations. Self made Tee's with two inch PVC pipe caulked with urethane caulk into a hole inside the four inch pipe (This is not EPA) makes more noise than standard Tees. This was part of the cause of the noise in the living area above. One self made Tee in the system is shown below: Mold in home made radon mitigation

15) The Tee's were removed and cardboard cylinders were found to be used as radon collector devices under the plastic. (Not a durable material and Not an approved EPA material for radon systems).
Mold in home made radon mitigation
Inside this cardboard pipe there was visible black mold growth.
The next picture shows the two self made PVC pipe Tee’s compared to a standard pipe 4”x2” Tee on the right.

16) There were two unfinished storage areas. The perimeter expansion material and grooves in concrete slab were only caulked for approx. 10%.

17) Sump pit in seperate unfinished area was not hermetically sealed (Not EPA).

After looking for alternative locations and their consequences on noise and checking the ten foot requirement for the distance of the radon dicharge point from windows on the second floor the home owner decided that he wanted to have a low noise replacement system installed at the same location.

After disassembling the exterior part of the existing system a Super Low Noise Exterior system was placed with special features to minimize exterior and interior noises and vibrations as shown in the following two pictures:

Exterior noise level reduced significantly as well as on both interior levels.
In the crawlspace, modifications were made such as 15 ft length of draintile pipe was attached to each side of the two new 4”x2” Tee’s under the radon barrier (i.e. 60 ft.of capped off draintile pipe total). Insulation was used to dampen noise where the 4” air stream is forced into a 2” air stream where the maximum speed of air increases a factor 4 compared to a 4” diameter pipe (if air can be considered incompressible for this purpose). The noise level inside was significantly reduced although the return ductwork is a very powerful resonant amplifier and not all noise was eliminated, but home owner stated he can now live with it.
The Sump pit was hermetically sealed and 15 tubes of caulk had to be used to finish caulking of the two unfinished storage areas.

Higher quality point (c) is addressed with these modifications, points (a) and (b) are not changed.


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