Levelling Step Between Original Slab and Beam & Block Floor

[Dean Mc]

Hi,

 

Sorry, possibly a stupid ‘newbie’ Q.
 

I have single story self build, which has two distinct areas of floor substructure; concrete slab and beam and block. The concrete slab was from the original building, but an additional limb was added which has a beam and block floor structure. 

There is a step where the two meet, which causes a void underneath when laying the 100mm Celotex insulation, which obviously flexes due to the lack of support beneath. The Celotex installation guide says ‘smooth with thin sand binding’ but I’m concerned that this may compact or move through time.

Should I be using a cement / concrete mix? Or something else?

[Russell griffiths]

Use a high build floor leveling compound. 

[Dave Jones]

concrete it so the insualtion is supported. put some damp under the conc

[saveasteading]

2 hours ago, Dean Mc said:

Should I be using a cement / concrete mix? Or something else?

You don't say how deep the step is.

Do you plan to raise the whole area or to grade it?

 

None of the above will compact. 

 

You have options. 

1.Cut the pir along the step. It will all sit solidly on the slab. The screed will fill it all to the finished level.

2. Screed a ramp or the whole lower area.

3.put thicker insulation in the lower area. 

[Dean Mc]

Thanks all. 
 

The step is approximately 10 to 15mm. The join is just under 5m wide. 
 

The length of the beam and block area is over 10m long and perfectly flat, so I was looking to grade it in underneath the 100mm  Celotex. 

Edited July 8, 2024 by Dean Mc