Concrete over dirt floor in crawlspace? (foundation, furnace, drains, convert)
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Our home has a walkout basement and the front portion of the basement [the part partially below grade] has a walk in dirt crawlspace.
We don't have any moisture problems [there were minor problems when we bought the house but that was fixed with rerouting some downspouts] but HVAC air handler, furnace, and downstairs ductwork as well as exposed plumbing and a sewage pump is in this space.
We also have two ventilated pipes which are under the plastic and connected to a radon vent fan.
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The area is about 15 x 30 feet and we would really like to put down a "floor" other than the plastic so we could walk about to inspect systems as well as take advantage of some storage space.
Any suggestions on problems we may face with doing this, things to look for in a contractor, etc? Right now the dirt floor is uneven - with the pump sitting in a trench [so it is lower than the drains in the finished "basement"]
My name is Mike and I am a New Jersey DEP licensed radon specialist.....I mitigate about 150 homes a year. First....I'd appreciate a little more indepth description of the radon fan set up in the crawlspace.....but for preliminary advice if your installing a concrete floor assuming there is already a radon issue you should install 4" of clean crushed gravel with a 4" diameter perforated pipe embedded in the gravel around the interior of the crawl space and then pour your concrete floor over that. By connecting your existing pvc ductwork to the new ductwork under the slab this will allow your inline radon fan to suck air from under the floor slab......its standard EPA/DEP radon mitigation protocol.
Quote:
Originally Posted by grannynancy
Our home has a walkout basement and the front portion of the basement [the part partially below grade] has a walk in dirt crawlspace.
We don't have any moisture problems [there were minor problems when we bought the house but that was fixed with rerouting some downspouts] but HVAC air handler, furnace, and downstairs ductwork as well as exposed plumbing and a sewage pump is in this space.
We also have two ventilated pipes which are under the plastic and connected to a radon vent fan.
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The area is about 15 x 30 feet and we would really like to put down a "floor" other than the plastic so we could walk about to inspect systems as well as take advantage of some storage space.
Any suggestions on problems we may face with doing this, things to look for in a contractor, etc? Right now the dirt floor is uneven - with the pump sitting in a trench [so it is lower than the drains in the finished "basement"]
We live in a high Radon area and homes built since 1993 must have a passive mitigation system built in - so the pipes as you describe are under the foundation - but we have to rely on the inspection when the house was built for that as well as radon testing [and we used a certified inspector who used an air sampling machine]
The levels came in just under the action limt so we added a vent fan to the system which dropped them by about 75% - but the cralwspace is not fully covered by plastic - perhaps 80% and I understand better sealing would also help.
I am glad you said that - I should probably contact the Radon Mitigation company who installed the vent fan and get more specifics on what needs to happen with the design.
We live in a high Radon area and homes built since 1993 must have a passive mitigation system built in - so the pipes as you describe are under the foundation - what do you mean "under the foundation"....you mean in the basement ? but we have to rely on the inspection when the house was built for that as well as radon testing [and we used a certified inspector who used an air sampling machine] That air sampling machine is called a contiunous radon monitor and they are very accurate.
The levels came in just under the action limt so we added a vent fan to the system which dropped them by about 75% - but the cralwspace is not fully covered by plastic - perhaps 80% and I understand better sealing would also help. Are you saying there is NO portion of the builder installed passive system in the crawl space ? There should be....it is required by code.
I am glad you said that - I should probably contact the Radon Mitigation company who installed the vent fan and get more specifics on what needs to happen with the design.
If it was installed at the time of construction it probably wasn't done by a certified company but by the builders plumber.....unfortunately most are not installed correctly when done by a plumber !!!
First....what area are you in ?
Second.......if your in a designated "high" area thats a Tier One zone meaning at least 25% of the tests in your area are high.
Third.....if you had a passive system installed at the time of construction as required by the Radon Hazard Subcode in Tier One zones why is there no passive system in the crawl space ? It would have been required by code if its connected to the basement.
If it was installed at the time of construction it probably wasn't done by a certified company but by the builders plumber.....unfortunately most are not installed correctly when done by a plumber !!!
First....what area are you in ?
Second.......if your in a designated "high" area thats a Tier One zone meaning at least 25% of the tests in your area are high.
Third.....if you had a passive system installed at the time of construction as required by the Radon Hazard Subcode in Tier One zones why is there no passive system in the crawl space ? It would have been required by code if its connected to the basement.
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There already is a passive system in the crawlspace but I want to put a slab there and that will require changes to be made.
The passive system was converted,to active due to 48 hour test Radon levels near the threshold
At the suggestion of SC DHEC, we had the Radon test done by a specially licensed contractor, given the location of the house. [it was already built]- The Radon contractors have separete licensing by the state but, you are right, they do not oversee construction.
The mitigation company said that if the vent fan did not work, lowering the levels would involve going under the existing slab. He also indicated that many problems exist due to allowing the pipes to get clogged with concrete. Also indicated the current crawlspace configuration was fine. Fan did work.
The passive system was converted,to active due to 48 hour test Radon levels near the threshold
At the suggestion of SC DHEC, we had the Radon test done by a specially licensed contractor, given the location of the house. [it was already built]- The Radon contractors have separete licensing by the state but, you are right, they do not oversee construction.
The mitigation company said that if the vent fan did not work, lowering the levels would involve going under the existing slab. He also indicated that many problems exist due to allowing the pipes to get clogged with concrete. Also indicated the current crawlspace configuration was fine. Fan did work.
We have the same problem here in New Jersey.....many passive pipes are found to be clogged with concrete because no one takes any care to keep them clear when the slab is poured but then we are expected to make the existing system "work" !!!
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