I'm about to start on finishing our basement and I'm going to put down a subfloor of DMX AG along with 5/8" T&G OSB. Should I frame out my perimeter foundation walls before the subfloor or after? If I install them before, the 1/4" DMX gap will allow for any potential moisture to evaporate into the room. If I install the foundation walls after (and on top of) the subfloor, any potential moisture would evaporate between the wall and the foundation. Which is better?

Our house was built in 2016 and is a walkout with no water issues in the 2 years we've been there so far.

  • I put my walls on top of the sub floor usually but with the dmx the weight of a wall on top may crush it and not allow for it to breathe. With this in mind I would check with the mfg and if being inspected the inspector they may not allow it under the wall but it wouldn't be much difference than a sill seal. – Ed Beal Feb 13 '19 at 18:37
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    Thanks for the reply @EdBeal. The DMX is rated for 6,000 lbs/sqft so I don't think there is much concern for it being crushed under the weight of the wall. You have a good point about asking the inspector, I hadn't thought about that as I'm sure they have restrictions in place. – Jason Reed Feb 13 '19 at 19:07
  • I haven't used dmx but being that strong I probably would run it under the walls they are not load bearing. We use foam seal on the plate to protect the wood and that is load bearing. – Ed Beal Feb 13 '19 at 19:49

With the comment on 6000 lb/ sq foot I would run the DMX under the walls, I have not used DMX in the past but don't see a problem especially since its a non load bearing wall. Always a good to check with the inspector / mfg to make sure it will do the job as intended.

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