Plaster sits between the raw block wall and the finish you will look at every day. When it is flat and well bonded, paint and tiles go on cleanly with little filler and little waste. When it is wavy, hollow or cracked, the faults show through the paint under certain light, or appear months later as cracks and flaking. This checklist helps you accept plaster properly before finishing starts, and explains the common defects and how they are put right.
What plaster is and why it is worth inspecting
Plaster (liyasa in Saudi site language) is a cement-sand mortar applied to blockwork and concrete to give a flat, hard surface. Internal plaster is typically one main coat over a bonding coat. External plaster usually needs more care and sometimes more coats because it faces sun, dust and the occasional heavy rain.
This stage is your last cheap chance to correct things. A wall out of plumb or a corner off square can be fixed now with mortar. After paint or tiles, the same fix means breaking out and redoing.
Before plastering starts
Many plaster defects come from starting too early. Confirm that:
- Services in the walls are complete: conduits, pipes, AC lines and switch and socket boxes fixed in their final positions, with chases filled.
- Walls have been reviewed: no broken blocks, no large open joints, column ties in place. See block types and how walls should be built.
- Surfaces are clean of dust, mortar droppings and oil.
- Mesh is fixed over block-to-concrete junctions and wide chases to control cracking.
- The wall is dampened so the block does not suck water out of the mortar.
- A spatter or bonding coat is applied, especially on smooth concrete, to help the plaster grip.
- Screed dots and strips are set with line and level to fix the plaster thickness and give the straightedge something true to run on.
- Corner beads are fitted on external corners for a straight, protected edge.
The core checklist after plastering
Take a long straightedge, a spirit level, a builder's square, a strong torch and something hard to tap with. Then go room by room and elevation by elevation.
1. Flatness
Run the straightedge horizontally, vertically and diagonally. The gap underneath should be small and even, within the specification, with no waves or bellies. Then switch off the room lights and shine the torch along the wall at a low angle. Raking light reveals the ripples that would otherwise appear under gloss paint or concealed ceiling lighting.
2. Plumb
Check the wall with the level in several places. A leaning wall becomes obvious when doors, wardrobes and kitchen units go in, and where tiles meet the wall.
3. Corners
- Internal corners should be square and straight from floor to ceiling; check with the square at several heights.
- External corners should be sharp and true, without wobble.
- The wall-to-ceiling line should be one straight line, because any kink is very visible once painted or fitted with cornices.
4. Hollow spots
Tap the wall lightly at close intervals. A hollow sound means the plaster has debonded. Mark those areas to be cut out and redone.
5. Cracks
Look closely at column and beam junctions and around openings. Distinguish between:
- Random hairline map cracking, usually shrinkage from fast drying.
- Straight cracks at junctions, usually missing mesh or poor ties between block and concrete.
- Diagonal, continuous or widening cracks, which need an engineer's opinion before any finishing.
6. Openings
Measure door and window openings against the door sizes and aluminium frames ordered. Reveals should be straight and plumb, or doors will bind and windows will leave gaps.
7. Electrical boxes
Switch and socket boxes should sit flush with the finished plaster, in the positions and heights shown on the drawings.
8. Surface texture for the next finish
Walls that will be tiled, such as bathrooms and kitchen splashbacks, should be left with a slightly rougher key for tile adhesive. Walls to be painted need a finer surface. Make sure the crew has treated them differently.
9. Curing
Ask about the water-spraying routine and watch it if you can. Plaster that dries out on a hot day loses strength and develops hairline cracks.
10. Clean-up
Mortar droppings on floors, ceilings, boxes and frames should be removed before they harden, or they will get in the way of floor levelling and tiling.
Common defects at a glance
| Defect | Likely cause | Fix before finishing |
|---|---|---|
| Wavy surface | No screed dots, poor straightedge work | Re-screed or treat depending on depth |
| Hollow sound | Dry background, no bonding coat on concrete, dry mortar | Cut out and replaster |
| Hairline map cracks | Fast drying, poor curing | Suitable surface treatment before filler |
| Straight crack at column | Missing mesh or ties | Open up, fix mesh, replaster |
| Corner off square | Poor setting-out at corners | Correct with mortar before finishing |
| Recessed or proud boxes | Boxes fixed before plaster depth was set | Reset boxes flush with the surface |
Extra points for external plaster
- Adequate thickness in even coats, as specified, with mesh at every block-to-concrete junction.
- Grooves or joints in large areas where the design calls for them, to control where cracks form.
- Correct falls on ledges, parapet tops and window sills so water and dust run off.
- Avoid plastering at peak heat on sun- and wind-exposed walls, and spray more often afterwards.
Good external plaster is the base for any profile paint or cladding; see exterior profile paint and textured finishes.
How Marafi handles plastering
We start once walls have been reviewed and services are complete. We fix mesh at block-to-concrete junctions, dampen surfaces, apply the bonding coat, and set screed dots and strips by level before any plaster goes on. Supervisors and engineers check flatness, plumb and corners while the work is in progress, not only at the end. We follow the engineering drawings for opening sizes and service positions, use approved materials and keep to safe site practice.
Before finishing begins we walk the rooms with the owner and share photos of the stage. See Plastering, the next stage on Interior Finishing, and the full sequence on How we build. At the end of the project, our interior finishing handover checklist takes over.
Quick acceptance checklist
- Services complete and chases filled before plastering.
- Mesh at every block-to-concrete junction.
- Flat under the straightedge and under raking light.
- Walls plumb, corners square and straight.
- No hollow spots, no continuous cracks.
- Openings to size, boxes flush.
- Regular water spraying in the first days.
If your villa is at or approaching the plaster stage and you want it done properly, or want what has been done reviewed, contact us to arrange a site visit and an itemised quotation.
Frequently asked questions
How can I tell if plaster is flat?
Hold a long straightedge against the wall in several directions and look at the gap underneath, then shine a strong light along the wall from the side. Gaps should be small and even, within what the specification allows.
Are hairline cracks in plaster serious?
Usually they are surface shrinkage cracks from fast drying or poor curing, and they are treated before painting. Continuous, diagonal or widening cracks need an engineer to establish the cause.
What does a hollow sound in plaster mean?
It means the plaster has lost its bond with the block or concrete behind it. Hollow areas should be cut out and replastered before finishing, because they can crack or fall later.
How long should new plaster be kept wet?
It should be sprayed several times a day for the first few days. This matters most in the Riyadh summer and on sun- and wind-exposed facades, where plaster dries too quickly and cracks.
