Floor, wall & ceiling finishes
Gypsum board ceiling installation
Choosing between concealed-grid and lay-in ceilings, the seven-step concealed ceiling sequence from levels, hangers and grid to jointing and painting, and acceptance criteria.
In this article
Gypsum board ceilings conceal building services and finish the offices, meeting rooms, corridors and service areas of a factory. World Steel installs two main types: concealed-grid ceilings (the frame is entirely hidden above the boards) and lay-in ceilings (exposed grid with drop-in tiles), once the services above the ceiling have been installed, commissioned and accepted.
Choosing the ceiling type
| Type | Features | Suitable for |
|---|---|---|
| Lay-in | Part of the grid is visible; pre-painted or PVC-faced tiles drop into the grid; economical and easy to open for maintenance above; less refined appearance. | Corridors, technical areas, large spaces that need frequent access. |
| Concealed grid | Frame fully hidden, giving a seamless surface like a painted concrete soffit; refined appearance; higher cost and harder access to services. | Lobbies, meeting rooms, executive offices. |
Preparation
- Detailed shop drawings of the frame, ceiling levels, steps, cove light slots and access panels, approved by the supervising consultant.
- All services and equipment above the ceiling accepted; ceiling levels marked and the handover of levels recorded.
- Toilet ceilings are installed after wall tiling.
- Tools: hammer, tape measure, pliers, rivet gun, laser, chalk line, spirit level, screw gun, concrete drill, threaded-rod cutter, saw, screwdrivers; PPE and working-at-height measures.
Concealed-grid ceiling sequence
| Step | Work | Control |
|---|---|---|
| 1. Ceiling level | Transfer the +1.00 m datum onto the walls with a laser; measure up to mark the ceiling level and chalk a line between the marks. | A continuous line round the room. |
| 2. Wall angle, hangers | Fix the wall angle with nails at 20–25 cm. Drill into the concrete beams and slab at no more than 90 cm; set anchors and screw in threaded rods cut to length. | Turn the rods with pliers, never by bending them. |
| 3. Hanging the grid | Hang the main channels on the rods with nuts above and below (washer before each nut); join channel ends with self-drilling screws; clip in the cross channels at right angles and rivet the joints. | Channel spacing as designed, clear of lights and air diffusers. |
| 4. Levelling | String lines between the wall angles lengthways, crossways and diagonally; adjust the nuts to bring the grid into plane; rivet the cross channels to the wall angle. | Positions of cut-outs and hung equipment; any cut cross channel must be strengthened. |
| 5. Boarding | Hold the board tight to the cross channels and screw at 20–25 cm; stagger the boards, gaps no more than 3 mm; fill the screw heads with jointing compound. | Screw heads just below the board face, no bumps or dents. |
| 6. Jointing | Tape the joints between boards and between board and wall with mesh tape; press the compound in firmly, several passes in one direction. Use mesh corner beads at steps, partitions and arrises. | Accept the joints before skimming the whole ceiling. |
| 7. Skim and paint | After at least 24 hours: a thin first skim, then a second when dry, then sand; paint as for walls. | No ridges at the joints. |
Lay-in ceilings
The sequence is similar, except that steel wire replaces threaded rod because the ceiling is much lighter, and there is no screwing: once the powder-coated grid is assembled, the tiles are dropped into it.
Acceptance criteria
- Levels and dimensions as designed; ceiling level deviation no more than 2 mm.
- Flat, smooth surface with no roughness, ripples, paint build-up, runs or cracks; even colour with no brush or roller marks.
- Ceiling–wall junctions even in colour, crisp and free of cracks; cove slots and steps flat and square with sharp arrises.
- Vertical board faces no more than 3 mm out of true.
- Access panels tight, flush and in the same paint colour; gap round the panel no more than 2 mm.
- Gaps between ceiling boards less than 1 mm.
Common mistakes
| Mistake | Remedy |
|---|---|
| No vertical stiffeners at bulkhead faces | Accept the frame carefully before boarding |
| Services set out wrongly, ceiling patched | Cut openings only against the M&E contractor's signed set-out; patch properly and tape the joints |
| Screws standing proud of the board | Set the screw gun depth; heads just below the face |
| No tape at junctions | Tape everywhere and accept before skimming |
| Ceiling pieced together from small offcuts | Take down and refit; stagger adjacent boards by at least one cross channel, board length across the cross channels |
| Screws too far apart | No more than 20 cm at edges, 30 cm elsewhere |
| Ceiling paint on fittings and walls | Cut in with a brush at junctions |
Reference standards
The edition in force when the contract is signed applies.
- TCVN 8256:2009 Gypsum boards – Specifications
- TCVN 8257:2009 Gypsum boards – Test methods
- TCVN 5674:1992 Finishing works in construction – Execution and acceptance
