Raising a floor up off concrete slab

[maxdavie]

I need to raise the FFL up off a concrete raft slab by approx 76mm.  

It is a warm slab, so both DPM and insulation are beneath it.

To achieve this my plan was to install 50mm of PIR board and then float a P5 T&G deck over it, before using a latex levelling compound beneath a linoleum final floor finish. 

A local guy has carried this work out this work for me up to the T&G flooring. The work is shoddy and prompted me to do more research (much too late!) There are no expansion gaps anywhere and in places the floor bounces. 

On top of this, I'm told that no levelling compound - even if it has a degree of flex - is suitable for installation over a floated floor and should only really be used over one that has been mechanically fixed. 

I'm now thinking we need to rip it all out and start again. It's 25 Sqm in total - Grrrrrhhhhhhh! 

 

My new plan after ripping it out is to secure some 50mm battens into the slab with a DPC beneath (to protect them from a more or less constantly-curing slab). Then mech' fix the T&G flooring over these paying attention and adhering to all the guidelines re expansion joints etc etc. 

 

Before I make another £££ mistake. Can anyone see any issue with my new plan? 

 

Thanks!

 

 

 

[nod]

Even though the floor is mechanically fixed You will need to leave a clear expansion gap around the edge 

I normally use off cuts of The flooring every meter then  pull them once you have finished 

[PeterW]

57 minutes ago, maxdavie said:

My new plan after ripping it out is to secure some 50mm battens into the slab with a DPC beneath (to protect them from a more or less constantly-curing slab). Then mech' fix the T&G flooring over these paying attention and adhering to all the guidelines re expansion joints etc etc.

Why..?

Get a circular saw with a narrow base plate and cut the full border of the board removing about 20mm of the T&G.

 

Then get a box of 125mm concrete screws and starting in the far corner drill and insert a screw 100mm from each corner and space 400mm apart. Measure 400mm down and repeat the line but stagger it.

 

Now add a layer of 4mm ply over the top, glued and screwed to the T&G.

 

Now you can skim the lot and lay the LVT.