Why does plaster lose adhesion on Bosaso walls?

Plaster preparation skills gaps in Bosaso show up as loss of adhesion: the coat looks sound for weeks, then sounds hollow, lifts at the edges and falls away in sheets. The fault is usually in the backing, not the mix. Dust, dryness, smooth concrete and leftover release oil stop the plaster from gripping, and those conditions are easy to miss when a crew works fast.

Why does plaster lose adhesion on Bosaso walls?

Adhesion depends on the plaster mechanically keying into a rough, damp, clean surface. A dry, dusty backing pulls water out of the mix before it can set, so the contact layer never gains strength. On smooth concrete, the surface offers no key at all. Form release oil, curing compound and loose sand do the same job as a barrier.

A wall left exposed can be much drier and hotter than the air around it, and the suction can be strong. Wind accelerates the loss. The mechanism here is straightforward: the plaster needs moisture, roughness and contact. Ask the project's engineer or the block or concrete supplier what the material's suction is likely to be, and confirm all preparation requirements against the project's specification and engineer before work starts.

When does the preparation gap start on site?

The gap opens the moment the backing is finished, long before the plasterer arrives. Gang sizes, drying time and programme pressure all decide whether anyone dusts, wets or keys the wall.

• Blocks are laid and left dusty, with mortar snots and loose sand still on the face.
• Concrete is cast and struck, then left smooth with release oil in the pores.
• The wall dries for days in sun and wind, so suction rises.
• The plasterer starts a coat to keep up with the programme, without damping the wall first.
• Nobody records who checked the backing or when.

A thin scratch coat or a wet wall that has not been tested both look acceptable for a short time. Adhesion loss shows later, and by then the plasterer is on another job. Supervision should therefore treat preparation as a hold point that the finishing foreman clears before any coat goes on.

How do you check preparation before plastering?

Walk the wall yourself in the hour before the coat. Most faults are visible or audible without instruments.

• Rub the palm across the wall. If dust comes off, it needs brushing and damping.
• Damp a patch with clean water and watch how fast the sheen disappears. Fast suction means the wall needs wetting down before plastering.
• Look for oil sheen, curing compound, paint or smooth form faces. These need scabbling, a bonding agent or a spatter dash, as the specification requires.
• Tap existing plaster with a light hammer. A hollow note means the coat has already lost contact at that point.
• Ask for the mix proportions, water source and mixing method to be recorded.
• Ask a laboratory to test a sample from a failed area if the cause is disputed.

Where a defect is widespread, a trial panel on the same wall and mix is the cheapest check. Ask the finishing supervisor and the plastering foreman to agree the pass standard in writing before the full coat starts. Check what the contract says about making good and who carries the cost of rework.

What to do next

Agree a preparation hold point with the finishing supervisor today: nobody plasters until someone dusts, damps and checks key on the wall, and signs it off on a dated sheet. Photograph each cleared wall. If a coat has already failed the tap test, stop work on that elevation, record the extent, and ask a laboratory for a sample test before deciding on repairs.