So, I have this job with solid 3/4 and a concrete slab going. I called Mu__ican tech dept, the manufacturer, about how to go about this and they're/his thoughts. On their installation requirement sheet....the box says you can do a floating 3/4 ply over concrete, on grade with 6 mil plastic under it. Just like the NWFA says you can. My job has one wall that is below grade and 1/2 of another 20ft wall below grade.

I told the box my plan and what he thought. My plan is use MVP4 and one layer of 6mil on top of that, then the 3/4 ply cut to size like the N-dubaya-FA says to with maybe 15lb felt under it as well. But the box starts tellin me immediately that you cannot install solid below grade. I say...."It's not like I am going into a basement And if you allow solid over a regular slab without any vapor retarder under the 6 mil plastic whats the big difference"?

The box keeps on about it being below grade and my idea ( not really anything oringinal really ) might actually work. Now I know the box is supposed to say what he says but really...can't these people think outside the box once in a while?

My Wagner Rapid Rh sensor's are hitting 88's to 90's. Whats the big deal? Tell me what you think?

Now if it were engineered I would be allowed to do this the box way. But what is engineered really? A couple layer's of thin hardwood glued together.

Every day is a winding road.

If all the readings are right, and you dont see any grading or run off issues, I say go for it. They're just gonna give you a generic answer to cover their a_s. Like you said, they can't think out of the box. You know better then them, you know the readings, heck it's not like a 10' cut out basement. When you really analyze it.....there can be a good argument of the pure definition of "below grade". On top of the barriers your figuring, and floated subfloor....go for it, if you dont I will

Yea, but the reading's are not right. They are high. The house is built at the highest part of the mountain you can get. Down at the lowest part, near the back of the pool bathroom you can see where water is coming out of the rock face that was demo'd.

Industry box says 60 rh minimum for solid over concrete. But who the heck glues solid directly over concrete with no vapor retarder??? Beside ths last guy at this house. lol
This floor will not be adhered to the slab.

I think we need some new direction from the box, besides the ole clan.

That's what I'm sayin....statements are based on gluing solid direct. Methods change, but statements don't. I guess they figure why change the generic statement, when their covered.

My Wagner Rapid relative humidity tests were hitting 68 near the wall thats 3 ft below grade today, 85 in the middle of the room. Lookin great!