Direct stick flooring...

Hi all, new to the forums so go easy.

I have read through many posts, but i have found it hard to find a definitive answer on the subject. I plan on laying some solid oak pre-finished timber flooring (not engineered stuff, but solid oak from top to bottom) in a townhouse living area which happens to be the second floor, so it is a suspended slab using the direct stick method. I plan to use Selley's direct stick or maybe the Sika equiv. Im not fussed, just what even i can get my hands on, they all seem to do the same job.

The building was built 1975 so i assume the moisture content of the slab would be non existent? My question is, do i need to spread a waterproofer or vapor barrier first? Instructions with flooring do not indicate so, but i am unsure.

Before we all suggest other methods, i dont have the ceiling height to use bearers nor plywood so those options are out.

If it turns out i need to do this barrier, is there an adhesive product that is both an adhesive and moisture barrier which can be applied in one whilst sticking to flooring down.

Thanks in advance, any help would be great.

James


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