Snag the wet trades before the decorator arrives

The one-visit rule: a defect in plaster or screed found before decoration is one trade's return visit. The same defect found after painting is two — the wet trade to cut out and make good, then the decorator to re-finish. Miss it again until after flooring and it's three. The cheapest snagging walk you will ever do is the one between plaster and paint.

Plaster: what to check

• Flatness. Rake a torch beam across each wall (light held flat against the surface shows every hollow and ridge that overhead light hides). Check board joints, external corners and around sockets.
• Cracks. Hairline shrinkage cracking is common as plaster dries and is usually cosmetic; look harder at cracks that follow board joints, run diagonally from openings, or you can catch a fingernail in.
• Chases and patches. Anywhere the electrician or plumber cut in after first fix. Filled chases that sit proud or hollow telegraph straight through paint.
• Dry before decoration. Plaster and screed need their drying time — paint over damp plaster and the finish fails later, which becomes an argument about whose snag it is.

Screed: what to check

• Cracks. Fine crazing on the surface is usually cosmetic. Cracks you can drop a coin into, cracks running across bays, or edges curling upward at joints are the ones to log — they telegraph into tiled and boarded floors.
• Hollow spots. Tap-test with a heel or a broom handle. A drummy, hollow sound means the screed has debonded from the slab — a failure waiting for point-load, and far cheaper to cut out now than under a tiled kitchen.
• Surface dusting. Sweep a patch. If the surface keeps producing fine dust or rubs away under a boot, the screed is weak or was over-trowelled with water — floor adhesives will not bond to it.
• Levels at thresholds. Check doorways and room junctions where different floor finishes will meet. A step that gets hidden by ply and vinyl on plan becomes a trip edge in the built house.
• Drying time. The BS 8204 rule of thumb is about one day per millimetre of thickness up to 50mm, and longer per millimetre beyond that — under good drying conditions. A 65mm screed floated three weeks ago is not ready for vinyl, whatever the programme says. Before floor finishes go down, the screed should pass a moisture (hygrometer) test, not a calendar check.

The numbers that decide an argument

Why the numbers matter: "that wall looks a bit wavy" is an opinion the site manager can wave away. "12mm deviation under a 2m straight edge, photographed with the measurement in shot" is a defect outside tolerance. Bring the straight edge; photograph the gap with a tape in frame.

Do it the Snagga way

1. Walk each room after plaster and screed, before any decoration starts.
2. Torch flat to the wall, straight edge on anything doubtful.
3. Photograph every defect with the measurement visible.
4. Assign it to the trade the same day — not in a list at the end of the week.

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