Movement joints and microcement.

What a thin finish can and can't do

Microcement is a thin, hard finish bonded to what's underneath it. It follows the substrate. Where a slab or screed is designed to move, at structural joints, control joints and junctions between different substrates, the finish can't hold it together. It has to be detailed to move with it.

Which joints carry through

Structural (isolation) joints, control joints in slabs and screeds, joints over changes in substrate (for example, where a slab meets a suspended floor), and perimeter movement at walls. The joint layout is set by the slab or screed design and the engineer. We follow it; we don't move or remove it.

How they're finished

Joints are carried through the finish as a fine line, sealed with a flexible sealant colour-matched to the surface, or set out with a discreet profile where the design calls for one. Placed deliberately, a joint reads as part of the design rather than a defect.

Agree it before work starts

We review the joint layout with the design team and builder before we start, and the agreed positions are recorded in the Site Assessment report. Where the drawings don't show joints on a large floor, we raise it before tender, not after the finish is down.

What causes cracking

Covering over a moving joint, applying over a substrate that hasn't finished curing or drying, poor bond to the substrate, and mixing products from different systems. Each one is controlled at a different stage, which is why we test the substrate and use one manufacturer's system from primer to topcoat.