Moisture barrier below osb underlayment

[brettcjensen]

I had a flooring vendor lined up to install 3/4" x 4" solid white oak hardwood floors. I needed to raise my floor level by 1/2 inch and walked in after they had started. They had installed 1/2 inch osb with aquabar b underneath it. They were installing the wood directly onto the osb. Everything I have heard or read says that hardwood should be installed on top of a moisture barrier. Is what they were doing ok? Should I be laying another layer of aquabar b on top of the osb and then installing the wood on top, or just rely on the aquabar under the osb to be a sufficient moisture barrier?

I would like to have my wood installed on aquabar because it is just easier to work with and slide the wood but I am concerned about trapping moisture in the osb. Do I need to be worried about this?

The osb they installed is on top of what I believe to be 2x8 floor boards so 2" cleats would go into the floor boards by about 3/4 of an inch. Is this sufficient or should they have laid plywood?

Hopefully sending the installers home was justified They were also doing completely symmetrical stair steps in the hardwood layout on both sides of my fireplace. They said that avoiding that will mean I have to buy more wood while they are the ones that told me how much wood to buy. I thought stair steps where an industry standard look that should be avoided. I didn't officially fire them yet, just said I want to think about things.

Thanks!

 

[DennisT]

Stair stepping is a mark of someone that either is too lazy to do it right or too inexperienced to know better.

2x8 floor boards? Really? That's unusual. If they're 2x8 floor joists w/3/4" ply I would think 1/2" ply instead of the OSB would be better. If they're really 2x8 floor boards I'd still prefer plywood, as it will "tie" them together and produce a less flexible floor. The reason people use OSB is because it is cheap.

I don't think the Aquabar matters too much if it is between the sheathing and the subfloor, but I'm someone here is more knowledgeable about that.

 

[Ernesto]

There is no "rule or standard" against stair stepping. Just may look funky depending on how busy the flooring is ie lots of shorts etc.

The 2x8 is very common and can breathe with the aquabar over it. OSB to me is borderline unless it is new and not weathered.