Plywood on concrete

[camel307]

Hi People,

I had a dining room, which was higher than my kitchen. I have broke the screed away and am now looking at ways of building the floor back up to match the kitchen.

The obvious choice is screed, on top of the existing concrete.

However, I have considered laying a DPM on the concrete, then some thin insulation (house is late 70's so doesn't originally have floor insulation) and then screwing plywood into the concrete.

Does this sound sensible or will the plywood rot over time? I have considered this method to prevent the floor tiles from getting so cold?

Also, do I butt the boards up to one another (just thinking about contraction and expansion).

Thanks

 

[wrightwoodwork]

What depth do you need to build up. Let's says it's 150 mm at moment I would lay 100mm insulation then a 50mm screed. If you fix ply on top of the insulation it will cause bumps and hollows as some parts will squash up more than others. You can put ply on top of the screed thats one way. Or let's say you have only 75mm you could lay 50mm x50mm runners fixed and straightened at 600mm centers then fill in between with something like polystyrene or Rockwood Batts then lay 22mm chipboard

 

[camel307]

It looks like, I have about 30mm to build up.

Is chipboard suitable for laying tiles directly on?

 

[wrightwoodwork]

You can lay tiles on chipboard as an option you can get insulation for laying tiles on top of like warm up available from tops tiles