Prevention, not repair
Avoiding Liquid Screed Problems Before They Start
Most screed faults trace back to a few decisions made before or just after the pour. This is the prevention checklist we work through on every job.
Planning a pour? Let's design the problems out
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People search for screed problems when something has already gone wrong: a crack along a doorway, hollow-sounding patches, a floor that will not dry, tiles lifting. Our problem pages go into each of those one at a time. This guide takes the opposite view — it gathers the causes into one place so they can be designed out before the pump arrives.
Anhydrite screeds like Gyvlon and Gypsol crack very rarely, and when they do it is almost always because of a joint detail or restraint issue rather than the material. The same pattern holds for most liquid screed complaints: the floor did what the build-up let it do.
Below are the decisions that matter, roughly in the order they happen on site.
Six decisions that prevent most callbacks
- 1
Edge isolation all round
A perimeter foam strip lets the screed move without pushing against walls, columns and door frames. A missing or short strip is behind a large share of edge and corner cracks.
- 2
Joints where the building needs them
Doorways, narrow necks between rooms and changes of heating zone are where movement concentrates. Planning joints there is cheaper than repairing cracks there.
- 3
The right primer on the right substrate
Bonded pours depend on preparation — laitance, old adhesive, paint and dust removed by shot-blasting or grinding — and on the primer the chosen system names.
- 4
Enough cover everywhere
Thin spots over heating pipe or services are where cracks and telegraphing start. Pipework is clipped down and pressure-tested so it cannot float up during the pour.
- 5
A realistic drying plan
Walk-on in 24–48 hours is not ready for flooring. Drying is planned around the covering, the weather and the heating schedule, then confirmed by a moisture test.
- 6
Protection after the pour
No standing water, no heavy loads, no pallets of tiles on day three. Early damage is one of the easiest problems to avoid.
Anhydrite-specific traps
Calcium sulphate screeds have two habits that catch people out. First, the surface laitance must be sanded off before tiles or other bonded finishes, which is why we plan a return sanding visit on jobs that need it. Second, they should not be tiled with cement-based products without the correct primer, and they are not the natural choice for true wet rooms — a cement-based screed such as Cemfloor is usually the safer option there.
None of this makes anhydrite a problem material. It is simply a chemistry with rules, and most anhydrite complaints come from those rules being skipped.
Warning signs worth a phone call
- Cracks that follow a straight line — often a pipe run, a joint that was not formed, or a doorway
- A hollow sound when tapped, which can mean debonding on a bonded pour
- Moisture readings that barely move over several weeks
- Powdery or dusty surface on an anhydrite floor that was never sanded
- Tiles or vinyl lifting or blistering soon after laying
Where to go from here
If one of those signs is already on your floor, the matching problem page explains the likely cause and the usual fix, and our problems hub lists them all. If you are still at the planning stage, the most useful thing you can send us is the build-up and the floor finish — with those two facts we can tell you which of the six decisions above needs the most attention on your job.
Frequently asked
Planning a pour? Let's design the problems out
Send the build-up, the finish and the dates. We'll flag anything on your job that commonly causes trouble.