Plasterboard and skim (walls and/or ceilings): calculator for UK builders
Answer the measurements this calculation needs and JobBosh works out the materials with wastage and pack rounding, the labour hours by role, the plant, the waste and the site needs - then prices them from your own figures, a supplier's quotation or a dated price you record. Free, no account needed to start.
What it works out
- Material: Plasterboard 12.5 mm (2400 x 1200 sheets); Dot-and-dab adhesive (25 kg); Finish plaster (25 kg); Scrim tape
- Labour: Fix plasterboard; Two-coat skim
- Waste: Plasterboard off-cuts and bags (segregated gypsum waste)
The questions it asks
| Question | Unit / choices | Required? | Help |
|---|---|---|---|
| Area to board and skim | m2 | required | Walls: perimeter x height less openings. Ceilings: length x width. |
| Surface | one of: walls, ceilings, both | optional - default walls (labelled assumed) | |
| Fixing method | one of: dot and dab, screw to studs, screw to battens | optional - default dot_and_dab (labelled assumed) | |
| Board thickness | one of: 9.5, 12.5, 15 | optional - default 12.5 (labelled assumed) | |
| Remove existing plaster / lath first? | yes / no | optional - default no (labelled assumed) | |
| Ceiling height | m | optional - default 2.4 (labelled assumed) |
The norms behind it, with their sources
Coverage, productivity and wastage defaults you can edit; each carries where it comes from and is shown as assumed until your own benchmark replaces it.
| Norm | Value | Source | Tier |
|---|---|---|---|
| Plasterboard sheet area (2400 x 1200) | 2.88 m2/sheet | standard sheet | assumed |
| Board cutting waste | 10 % | trade practice; 15 % on fiddly rooms | assumed |
| Dot-and-dab adhesive per m2 | 3 kg/m2 | typical manufacturer figure; 25 kg bags | assumed |
| Drywall screws per m2 | 20 nr/m2 | trade practice | assumed |
| Finish plaster per m2 at ~2 mm | 2.6 kg/m2 | typical manufacturer figure; 25 kg bags | assumed |
| Scrim tape per m2 | 1.2 m/m2 | trade practice | assumed |
| Fix boards per m2 (dot and dab) | 0.35 hr/m2 | trade practice | assumed |
| Two-coat skim per m2 | 0.3 hr/m2 | trade practice; ~3.5 m2/h | assumed |
| Hack off / strip existing per m2 | 0.25 hr/m2 | trade practice | assumed |
| Rubble from stripping plaster per m2 | 0.03 m3/m2 | trade practice | assumed |
A worked example
Answers used: Area to board and skim 20 m2; Surface walls; Fixing method dot and dab; Board thickness 12.5; Remove existing plaster / lath first? no; Ceiling height 2.4 m. These are the recipe's own quantities for those answers - the prices are yours, the supplier's or a quotation's, never a figure typed on a web page.
| Kind | Line | Quantity | How it is worked out |
|---|---|---|---|
| material | Plasterboard 12.5 mm (2400 x 1200 sheets) | 7.64 sheet 8 x sheet - 2400 x 1200 mm sheet = 2.88 m2 | 20 m2 / 2.88 m2 per sheet, +10 % cutting waste |
| material | Dot-and-dab adhesive (25 kg) | 60 kg 3 x bag - 25 kg bags | 20 m2 x 3 kg/m2 |
| material | Finish plaster (25 kg) | 54.6 kg 3 x bag - 25 kg bags | 20 m2 x 2.6 kg/m2 |
| material | Scrim tape | 24 m 1 x roll - 90 m rolls | 20 m2 x 1.2 m/m2 |
| labour | Fix plasterboard | 7 hr | 20 m2 x 0.35 h/m2 |
| labour | Two-coat skim | 6 hr | 20 m2 x 0.3 h/m2 |
| waste | Plasterboard off-cuts and bags (segregated gypsum waste) | 0.2 m3 | 20 m2 x 0.01 m3/m2 |
Labour on this example: about 13 hours across the roles; at your rates it becomes money.
Site questions this work raises: Protection and cleanliness, Utilities and welfare, Waste.
Plasterboard off-cuts are gypsum waste: segregate from general rubble (tips refuse mixed loads).
Then what
Price the lines from your crew rates and your material prices (each with its source and date), answer the site questions (parking, skip, welfare, power, water, protection), let JobBosh draft the supplier enquiries you approve, and issue a branded quotation your customer accepts on a secure link. Guest work is kept for 14 days; a free account keeps it for good.
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