Plastering a loft conversion involves more complexity than standard room plastering — there are angled ceilings, knee walls, dormer cheeks and stud walls to deal with, plus restricted access. Here is what to budget.
Loft Conversion Plastering Costs
| Conversion type | Plasterboard & skim cost |
|---|---|
| Small Velux loft room (20–30m²) | £1,500–£2,500 |
| Dormer conversion (35–50m²) | £2,500–£4,000 |
| Hip-to-gable conversion (50–70m²) | £3,500–£5,500 |
| Mansard conversion (70m²+) | £5,000–£8,000+ |
Why Is Loft Plastering More Expensive?
Several factors increase the cost compared to standard rooms:
- Angled ceilings — cutting and fitting plasterboard to follow roof pitches takes longer than straight walls
- Restricted access — materials need to be carried up multiple flights of stairs
- More boarding area — sloping ceilings have more surface area than the equivalent flat ceiling below
- Multiple wall types — stud walls, dormer cheeks, knee walls and ridge points all meet in unusual ways
What Specification Does Loft Plastering Need?
12.5mm standard plasterboard is typically used throughout. Where the loft is directly under roof tiles, 15mm vapour-check plasterboard with a vapour barrier is recommended. Fire-rated board may be required on the party wall for semi-detached and terraced properties.
Timing in the Build Programme
Plastering typically follows insulation installation, first-fix electrics and plumbing. The plasterer works before second fix (sockets, lights, flooring). Build in 4–6 weeks drying time before second fix and decoration.
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