I recently bought a house built in 1996. It has a 1480sq ft (approx) living area, which is the same as the crawl space size. The location is in the Kansas City metro area. The yard is sloped up from the road, I would say about 10' higher. I have about 10-12" slope from the house walls to the yard to prevent water from building up beside the foundation. I regularly keep my gutters clean (PITA) and the roof has a good 10-14" overhang.

The height of the crawl space is probably 40-48" or so, enough for me to walk with knees bent and hunched over (I'm 6'2" tall). The crawl space has two sump pumps, geo thermal HVAC unit (two pipes run through the crawl space for it), and a main water feed line (at least I think it is). The floor has gravel, and digging through it with my hand, I noticed there already is a thin vapor barrier, however, it does not go up the walls. It seems to end right at the wall. My crawlspace stays cool and dry. I do not see any issues with my joists or floorboards (there's no insulation between the joists).

The entrance to the crawl space is from the garage. The garage has been cleaned and finished (epoxy flooring, painted walls, all walls insulated, etc). So the likelihood of debris entering will be minimal if at all.


When I bought the house I was tested at 4.6 for Radon. I received several quotes for radon mitigation and they all come in over $2300 for parts/labor which includes sealing the crawl space floor and running a vent from one of the sump pumps.

Action Items

  1. If nothing else, I'd like to accomplish lowering my radon levels (vapor barrier attached to wall and fan/plumbing out through roof).
  2. I would like to insulate the exterior walls to help keep my house energy efficient, and warmer floors in the winter time. I plan to replace the carpeting with laminate flooring.
  3. Completely seal the crawl space, add an AC vent and return and make it a conditioned area.
  4. Once sealed, use this area for storage and build a patch panel wall for Ethernet, phone, and coax cable connections. Possibly place a server and network switch as well.

Skill Level

I consider myself handy. I've done laminate flooring, replaced toilets, tiled bathrooms, worked with electrical and plumbing, etc. I would always hire someone when in doubt. I'm not afraid to get help when needed.

I only have time on weekends, so if not completing a task until the following weekend or spanning the entire project over multiple weekends is not acceptable, please bring this up for one of the tasks mentioned.


Solving the radon:

Would placing a vapor barrier over the existing vapor barrier and gravel be acceptable in terms of installation or would it be better to remove the existing barrier and gravel first?

Would doing this alone while keeping the crawl space vented reduce the radon without placing a fan and plumbing to exhaust the radon out past the roof?

Solving the energy efficiency:

After installing the vapor barrier and sealing it up 12" to the wall, what is the recommended method for installing foam boards to the exterior walls: do I have to keep it a certain distance from the floor; from the joist?

Can the foam boards lay over the vapor barrier on the wall?

Once the foam panels are installed with the vapor barrier, can I continue to leave the vents opened until the hvac system has a vent and return in place for the crawl space?


Once sealed and conditioned, is there any maintenance to be done in the crawl space?

Anything to look out for on a monthly, quarterly, annually basis?

Should I be measuring temperature/humidity in the crawl space? Will temperature and humidity fluctuate a lot?

Storage and other:

Once sealed and conditioned, is there any items to avoid storing since it will be sealed (ie paint cans, oil, etc)?

For building a patch panel and network/electronics, will it be an issue in the crawl space now? I'd assume having it sealed will provide a much cleaner and "controlled" area going forward.

  • You have asked the same questions that I am interested in knowing but I have no answers. Did you figure any of these out on your own and can you give us an update? – user50605 Feb 23 '16 at 19:14

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