What type of compound for smoothing between diff. heights?

[smp50]

Hello. I have a room which was once two, and now half the room has a concrete floor and half has floorboards (on concrete):

However, unlike that diagram, the wooden part of the floor sits 2-5mm lower than the concrete and that's very noticeable through carpet and underlay (which is what I'm putting down over the whole lot).

In the past, someone had smoothed over this little step with some grey brittle compound, extending about 1ft onto each surface either side of the step, so that the transition was more gentle and, if I remember correctly, barely noticeable under the carpet that was there. I have no idea what this compound was, though. Here you can see it remaining on the concrete side (top) but chipped off the wood side (bottom) as I needed to replace those boards.

Can anyone suggest what would be suitable to use in this case? Or any other solutions I may not have thought of.

Thanks,

 

[ree]

Why not do what was done before - only a little better perhaps?

Knock off the "compound" on the concrete.

You could prep the boarded area with PVA and then when the second coat of PVA is tacky, apply a thin layer of self levelling compound (SLC) to meet the concrete edge.

Use a steel trowel to feather the SLC back to nothing.

Carpet with underlayment should wear and feel fine over the irregularity.

 

[smp50]

Why not do what was done before - only a little better perhaps?

Knock off the "compound" on the concrete.

You could prep the boarded area with PVA and then when the second coat of PVA is tacky, apply a thin layer of self levelling compound (SLC) to meet the concrete edge.

Use a steel trowel to feather the SLC back to nothing.

Carpet with underlayment should wear and feel fine over the irregularity.

"Self-levelling compound" will be what I need, then? Such as this: http://www.screwfix.com/p/no-nonsen...ing compound&gclid=CIbWjtWa3bwCFYWWtAod2zUATw ?


I've never used it but I always assumed that stuff is meant to sink down to a flat level and has to be "contained" somehow, no? If it can be shaped and will hold that shape then it would work OK here.

 

[crazydaze]

You would shape it 'by eye' using a straight edge and apply it with a trowel, it shouldn't really be used direct to wood, i'd use micro-coat or feather edge built up in layers.