solid wood flooring over concrete sub floor

[Dan Stewart]

Hi folks,

I am looking for an expert in laying wooden flooring. I am really struggling to find good advice on laying a solid wood floor (reclaimed yellow pine 100mm x 25mm) over a concrete sub floor. The concrete is likely to have been down some 80 years and is very likely to not have a DPM. In addition moisture can be seen on the concrete in places where it is wicking through from the external stone walls. The concrete is quite uneven with a lump in the middle of the room some 35mm higher than the edges of the room - how do I sort this? Can I grind down the high spots then use self leveling compound? It would be too much to level up to the highest spot!

I was hoping due to height restrictions to stick the floor down using a Sikkabond or Rewmar product. The suppliers of the products both advise some sort of liquid DPM but state that depending on moisture levels the DPM may fail and blister causing the floor glue to eventually fail. The cost of these products are also more than the flooring itself!! If I buy or hire a moisture reader (also not cheap) I am afraid it will confirm the inevitable and tell me that the floor is above the recommended 60% relative humidity.

Glueing a wooden floor to concrete goes against the grain with me and the other option would be to use a polythene DPM and use wooden battens to fix to. The issue I have with this method is how to screw the battens through the DPM as surely this would create a hole for moisture to come through? Should I be floating the battens on the DPM?

Any advice on a way forward with this would be appreciated. We already have the flooring so would prefer not to revert to carpet!!!

Thanks for your help.

[welsh brickie]

paint the floor with aquapruf buitumin paint and drill and fix 50mm x 25mm treated battens to the floor at 400mm centres you can pack them level to take the unevenness out of the floor, and then lay 25mm polystyrene inbetween the battens to give you insulation, Your new floor can then be laid on top

[Dan Stewart]

Cheers for the prompt reply Welsh Brickie. You don't think there will be any issue with moisture coming up through the fixing points of the battens? I presume you would stay away from the glue down method?

Cheers for your help.

Dan

[welsh brickie]

moisture through the screw will be negligible, with pine you will get movement and it needs to expand and contract the glue will create problems not solve them.

[Dan Stewart]

I am going to really struggle with the batten system as the boards are 25mm thick. Assuming the battens are the same thickness, this would raise the floor by 50mm which I just cannot get away with. May have to glue down!

The glue is supposed to be elastic in nature allowing for movement of the boards.

Has anyone else had experience of gluing down sold boards?

Cheers

Dan

[welsh brickie]

if your really stuck for height,and the floor is that uneven, then remove the hump in the floor with a grinder,lay a self level compound and laminate flooring instead its only 8mm.