Three common causes of cracks and when to insist on a mesh interlayer.
Three causes of cracks
Cracks almost always trace back to three things: drying too fast, insufficient priming, and bad mix ratios. Each of these mistakes is easy to avoid if the crew works methodically rather than rushing.
Where two substrates meet — for example brick next to drywall — a mesh strip across the joint pays for itself many times over before the first skim coat goes on. A few zlotys per metre that save a repair costing hundreds.
Temperature and humidity — a quality requirement
Ideal conditions are 18–22°C and relative humidity below 65%. At too low a temperature, the skim sets unevenly; too high and it loses elasticity too quickly.
That's why in winter we always ask clients to keep heating on during the works — not as a luxury, but as a condition of the quality guarantee. Without proper temperature, even the best skim won't perform.
Two coats — the decade-long difference
Once the first coat has dried, sanding and applying a thinner finishing layer is essential. Skipping this step is one of the most common shortcuts taken by cheap crews.
The result looks fine for a month, then hairline cracks appear, most visible in raking light. Two coats and proper sanding is the difference between a wall that lasts one year and one that lasts a decade.
