Our wooden floor which was laid directly on a slab has lifted. The slab is wet and the boards have been removed. We need to lay a new floor. I have been advised to seal the concrete then use plastic on top and then battens to level it, however the flooring company who is subcontracted by our insurance company us refusing to do the job saying that battens are not used anymore in Australia as they absorb moisture. I am not sure how to fix our problem. The slab is not in great condition and has no membrane. Any advice would be fantastic.

Clairem,

First you need to fix the reason why there is a moisture problem. Only then you may consider if laying a wood floor is the right thing to do for you.

If the moisture problem can not be fixed forget about wood flooring, the water will find it's way to the wood floor.

Go around the house and check the slope of the land, any rain water draining next to the house is bad, direct rainwater away from your home with the use of downspouts and proper sloping/grading of the land. What about the lay of the land? If you are in a low laying area with a high water table a wood floor is pretty much out.

You say "the slab is not in great condition" which is the first thing to take care of! I'm surprised that these basic things were not first recommended to you to be looked at and get fixed. Just reinstalling a new floor and only "attempting" to keep the water out is like throwing money away.

Johannes.

If you see water on the slab it could also be a dewpoint problem. Don't any of those people there have thermohygrometers and an infared thermometer to check the slabs temp and ambiet rh and temp?

Here is a good tutorial about dewpoint issues on slabs. You should also have the slab tested using the relative humidity with interior temp test, in U.S called ASTM F-2170-11.

http://www.pbawichita.com/blog/4/dew-po ... tallations

Here is another example with a dewpoint chart on the scecond page. http://www.buildwithbps.com/assets/down ... 0Chart.pdf

Slab being physically wet with actual water, is not a good thing for wood. I hope they used pressure treated wood as bottom plates in the walls!


Dew point is a real possibility. HVAC with a humistat will pull the humidity out.

Solid over concrete is never a good idea.

I will only do it with a floating plywood subfloor, over a tested and passing concrete slab.