Plasterboard
Plasterboard screws per board and per m²
- where
- number of support lines under one board
- board dimension across the studs or joists (mm)
- stud or joist centres (mm)
- screws along each support line
- board dimension along each support (mm)
- screw centres along each support (mm)
- screws per board
- screws per m²
- screws for the area
- area to board (m²)
- waste allowance (%)
Explain this equation
This counts drywall screws per board and per square metre when boards are fixed at the maximum screw centres, then scales up to your area. Use it to order screws for walls or ceilings.
nl is how many studs or joists a board crosses, including both edges. ns is how many screws go down each one at centres c, including one at each end. a and b are the board dimensions across and along the supports. Nb is screws per board and Nm screws per square metre.
Supports and screws are counted as fence posts: a 1200 mm board on 600 mm studs touches three studs, and 2400 mm at 300 mm centres takes nine screws. The 1,000,000 turns mm² into m². The screws total is rounded up.
Sense check: a wall board on 600 mm studs at 300 mm centres takes 27 screws, about 9 to 10 per m². A ceiling board across 400 mm joists at 230 mm centres takes about 49, roughly 17 per m².
Watch out: this is field fixing only. Add extra for 200 mm centres on external corners and 150 mm at ceiling board ends and perimeters.
Counts drywall screws for a board fixed to studs or joists at the British Gypsum maximum centres, then scales to your area.
Enter your values to see the result.
Good to know
British Gypsum and NHBC: screws at maximum 300 mm centres on walls and 230 mm on ceilings, closer (200 mm at external angles on walls, 150 mm at ceiling board ends and perimeters) where recommended; not less than 10 mm from bound edges and 13 mm from cut edges. Wall boards usually stand vertically, so the 1200 mm width crosses studs at 600 mm (3 lines). Ceiling boards usually run across joists, so enter a = 2400 mm across 400 mm joists and b = 1200 mm. The count includes both board edges, as each board is screwed along its own edge.
Common mistake
Using wall spacing (300 mm) on ceilings. Ceilings need 230 mm centres, roughly 70–80% more screws per m² once joist spacing is taken into account.
Limits
Field fixings only: add extra screws for closer perimeter spacing, noggings and external angles. Assumes every support line under the board is fixed.
Sources
- British Gypsum, BS sub-clauses (screws at max. 300 mm centres on walls, 230 mm on ceilings; 10 mm from bound edges, 13 mm from cut edges; dabs ≥ 20% contact)
- NHBC Standards 9.2.4 Dry lining (Table 7 screw centres; Table 9 adhesive dabs 50–75 mm × 250 mm at 300 mm centres, 3 rows per 1200 mm board for 12.5 mm)
- BS 8212:1995 Code of practice for dry lining and partitioning using gypsum plasterboard
Results are calculations from the published methods and manufacturer figures shown, and depend on the data you enter. Always follow the manufacturers’ system and product data, BS 8212, BS EN 13914 and Building Regulations. Coverage rates vary by product, background and thickness. Check prices, VAT and CIS rules with your own records and HMRC.