Floor Screed Supply in Nairobi: Sand-Cement and Pumped

Screed is not concrete

They look similar and they are not the same material. Concrete carries structural load. Screed is a levelling layer laid over it to receive a floor finish, and it is made with sharp sand rather than coarse aggregate.

Using one where the other belongs is a common and expensive Kenyan site error. Structural concrete as a screed leaves a surface too coarse to tile onto reliably. Screed used structurally cracks.

The mix is the whole thing

A screed gauged by the shovel is the single biggest cause of floor failure we see. Too much cement and it curls at the edges as it dries. Too little and it never reaches strength, then breaks up in traffic and takes the tiles with it.

We batch to a controlled mix and state it on the ticket. On a floor that is about to receive expensive tile, timber or epoxy, that ticket is worth considerably more than the small saving from site-gauging.

Depth and bond

• Bonded, 25 to 40mm, laid onto a prepared and primed slab.
• Unbonded, 50mm minimum, over a membrane.
• Floating, 65 to 75mm, over insulation or acoustic layer.

The depth is not a preference. Below the minimum for its type a screed will crack, and it will crack in the pattern of whatever is underneath it.

Drying time is fixed by chemistry

The rule of thumb is a day per millimetre for the first 50mm, and longer beyond that. Nairobi’s humidity in the long rains extends it further.

You cannot compress this to suit a programme, and laying an impermeable floor finish over a screed that has not dried is how you get a floor that lifts six months later. If your programme does not allow the drying time, the honest conversation is about the programme.