Raising a concrete floor by approx 2 inches.

[Donwill]

Within a kitchen/diner extension I need to raise an existing conc floor approx 2 inches for two reasons:-

1. To reduce the internal cill height of two external doors, presently approx 4 inches..
2. To enable SWMBO to see the garden over the window cill when sitting at a table.
3. To enable me to bury / conceal CH pipes which have to pass in front of two external doors.

I am going to tile the floor afterwards and because of the drying time and mess of a wet screed, I'm inclined to lay a wood floor to bring it up by 2 inches approx and lay tiles using a good flex tile adhesive.

Should I use say 30mm bearers and perhaps 18 mm ply, What bearer spacing should I use to reduce flexing?

or should I use two or even 3 layers of ply (expensive?)

Should it be a floating floor or fixed (screwed to concrete).?

any recommendations please. Don

[The Natural Philosopher]

All methods will work.

Why not use studs, and fill the gaps with celotex as well?

I'd also be inclined to add UFH as well..kitchens are hard places to site radiators..

[Christian McArdle]

400mm or thereabouts.

Nah.

I'd fix this.

For tile adhesive, use Ardex Flex 7001 Timber System.

[meow2222]

sounds ideal.

30mm wood is very cheap, and the closer the better. Also you can dot all the offcuts about halfway between the bearers, these little bits will stiffen it up even more.

no. For a moment I wonderd about layered chip, but you need to run things down there, you can insulate the space, and chip comes apart once wet.

if no floor insulation, I'd insulate it.

NT

[Donwill]

Many thanks to all for the info. Best Regards Don