Looking at P5 boards and celotex instead of celotex and screed

[Brian in Dorset]

Following 3m ground floor extension and loft conversion i am looking to raise the height of existing concrete ground floor. (floorplan attached).

 

There are currently smallish differences in floor height between rooms and hall and a little bit of "out of level".

 

I have been looking at an increase of about 100-120mm and we increased downstairs wall height by a whole block.

 

I am considering 50mm celotex and 50mm flowing screed which will allow me a bit of tolerance with celotex levels etc.

 

I am now thinking about 80mm celotex and 22mm P5 boards.

 

is it possible for a competent DIYer to get a level enough surface on top of celotex to fit the boards and for the whole thing to be acceptable result?

 

Is there a foolproof way to sort out differences of level (maybe 3mm over metre) and level (maybe 0-15mm) between rooms.

 

The boards look increasingly tempting but i am worrying about the final result.

 

Any advice regarding boards and celotex appreciated.

 

Thanks

 

Brian

 

 

 

 

[Russell griffiths]

Nope, it’s known as a floating floor, all boards are glued so act as one sheet. 
I worked at a site that did this. 
if you stamped on the floor at one side of the room the telly would jump up and down. 

[Brian in Dorset]

Thanks for the advice Russell, much appreciated.

 

Leaning towards screed again. Dont want the TV to be jumping around.

[Mr Punter]

I have done a few floating floors with 22mm T&G chipboard over insulation and have not had any issues with bounce.  It weights about 16Kg per m2, so a 4m square room will be a quarter of a tonne.

 

It needs to be installed correctly - left in the room to acclimatise, 10mm expansion gap all round.  If you have tiles you could use a fibre cement type instead of chipboard.

[bassanclan]

I've got a floating floor in my extension that the previous owner installed.

I wish i had dug it up and screeded it every time I walk on it!