I recently purchased and moved into a new house with an unfinished basement under part of house and crawl space under the rest. We have 2 indoor cats and I would prefer that their litter box be in the basement. There is access to the basement from in the house and from outside. I'd like to put a cat door on that internal door to allow them free access down to the basement, but I'd like to make sure I'm not going to increase radon levels in the main floor of the house. I believe radon is too heavy for this to be much of an issue since the door would be at the level of the main floor of the house, but better safe than sorry.


  • We do have a radon mitigation system
  • A radon test on the main floor of the house passed before we bought the house (meaning the radon system is working), but we did not test levels in the basement/crawl space
  • The door is a fairly standard inside room door


  • Is there a particular type of cat door that would be best for this situation?
  • Is there anything else I should do or consider before, or during, installation to reduce the risk of increased radon?

If you have a Radon Mitigation system, then you should have no worries. A proper mitigation system puts a negative pressure on the underside of the basement slab, and vents it out the roof. The idea is to remove all radon from the basement itself.

So, in theory, a cat door should have no bearing on the amount of radon in the first floor.

I'd, of course, do a radon test in the basement to be sure, but you should be fine.

  • But what about the cat door?
    – Tester101
    Nov 20 '12 at 20:35
  • 1
    @Tester101 nothing, I guess. My point is that it doesn't matter.
    – DA01
    Nov 20 '12 at 23:05

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