Cracked, flaking or stained ceiling in Geneva: causes and repair

Read the symptom before repainting

Painting over a defect without understanding its origin is a sure way to see it return. Every mark on a ceiling has a visual signature that guides the diagnosis, and therefore the repair.

Symptom	Likely cause	Typical repair
Fine, fixed crack	Plaster shrinkage, ageing	Reinforcing tape or flexible filler
Crack that widens	Structural movement	Bridging tape, monitoring
Dry flakes	Loss of adhesion, old surface	Scraping, bonding primer
Blisters, soft paint	Moisture or leak	Drying out, stain-blocking primer
Yellow or brown stain	Leak, water ingress	Cause first, then sealing
Grey film on the ceiling	Smoke, candles, condensation	Washing down, sealing primer

An examination under raking light (a lamp placed close to the ceiling) reveals defects invisible under overhead lighting. This is the first step during a visit.

Cracks: plaster shrinkage or structural movement

Not all cracks are the same. The distinction entirely determines the repair.

Shrinkage cracks — fine, often forming a network or following a plasterboard joint, they no longer move. They come from the drying of the plaster, seasonal variations in humidity or the age of the building. In the older Geneva housing stock (buildings in Eaux-Vives, Champel, Plainpalais), they are common and harmless. Repair: lightly opening up the crack, applying a reinforcing tape or flexible filler, sanding, then an even finish.

Structural cracks — wider, sometimes stepped, they may lengthen or reopen. They reflect movement in the surface (settlement, expansion, flooring). A reinforced bridging tape absorbs part of the movement, but if the crack is still working, it is better to understand the cause before the finish.

When in doubt, its progression is observed and the appropriate repair is recommended rather than masking it.

Flaking and blisters: moisture or adhesion

Ceiling paint that flakes or blisters falls into two quite distinct families — and the treatment is not the same.

Loss of adhesion (dry) — the paint comes away in dry flakes, often on an old ceiling repainted several times, a dusty surface, a coat applied without preparation or over a surface that is too smooth. The repair involves scraping off the loose areas, dusting down, applying a bonding primer, then finishing.

Flaking from moisture (blisters) — the paint blisters, softens, comes away in damp patches. Here, water is the cause: chronic condensation in a poorly ventilated room, or a leak. Repainting over a surface that is still damp will not hold. You first need to identify and treat the source, let the surface dry all the way through — drying out after water damage generally takes several days and is checked with a moisture meter — then apply a stain-blocking primer before the finish. See our ceiling service.

Yellow stains, water marks and smoke traces

Coloured stains on a ceiling each have a recognisable origin.

Yellow or brown stain — a sharp outline, sometimes ringed by a darker edge: this is the signature of a leak or water ingress that has migrated into the surface. As long as the cause is active, repainting is pointless: the stain bleeds through the finish. Once the leak is resolved and the surface dry, a stain-blocking primer prevents tannins and salts from rising through the paint. Without this step, the stain reappears even under several coats.

Smoke traces and grey film — a diffuse deposit above a radiator, an open-plan kitchen, or left by candles. The surface is washed down first (soot is greasy), then receives a sealing primer to lock in the residual deposit before painting.

When the origin is a declared water-damage claim, the protocol is more thorough: see our water-damage repair service.

The repair in the right order: treatment, primer, matt finish

A lasting ceiling repair follows a physical sequence, whatever the starting defect.

1. Diagnosis and treatment of the cause — crack stabilised, leak resolved, moisture brought under control. This is the condition for everything that follows.
2. Preparation — scraping off flakes, opening up and filling cracks, washing down greasy deposits, sanding.
3. Suitable primer — a bonding primer on a closed surface, a stain-blocking primer on a water mark or smoke trace. The choice depends on the symptom.
4. Matt finish — on a ceiling, matt is almost always preferred: it absorbs light and hides micro-reliefs, where a satin finish would reveal every defect under raking light.

Between coats, drying takes a few hours; a faint residual smell may linger for a day or two. Renovhome SA uses paints with low VOC emissions. The aim: a ceiling that visually disappears, with no roller marks or joints. See the painting glossary for the terms used.