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FREE WASTE GUIDE FOR DRYLINING CONTRACTORS

Drywall screw lengths: which plasterboard screw to use

A drywall screw needs to be long enough to go through all the board and at least 10mm into metal framing, or at least 25mm into timber. That's the rule on British Gypsum's screw data sheets. Knauf and Siniat both work to 10mm into metal, and Siniat also gives 25mm into timber.

The figures below are British Gypsum's, with Knauf and Siniat in brackets where they differ. Always check the system specification for the wall or ceiling you're building.

Screw length for metal studs

Add the total board thickness to 10mm, then round up to the next length you can buy. With British Gypsum Drywall Screws:

Board

Minimum length

British Gypsum screw

1 x 12.5mm

1 x 15mm

2 x 12.5mm

12.5mm + 15mm

2 x 15mm

22.5mm

25mm

35mm

37.5mm

40mm

25mm

25mm

35mm

40mm

40mm

On double-layer walls, fix the inner layer with the short screw and the outer layer with the longer one, through both boards into the stud.

Merchants may also stock drywall screws in 32mm, 38mm and 42mm, which are Siniat's sizes too. The same rule applies: with those lengths, 2 x 12.5mm and 12.5mm + 15mm take 38mm, and 2 x 15mm takes 42mm.

Board thicknesses are covered in plasterboard thickness and sizes.

Screw length for timber

Board

Minimum length

1 x 12.5mm

37.5mm

Into timber the rule is the board plus at least 25mm. British Gypsum's 25mm Drywall Screw is for metal only. Its 35mm and longer Drywall Screws are made for metal or timber.

1 x 15mm

2 x 12.5mm

2 x 15mm

40mm

50mm

55mm

Siniat uses a coarse-thread High Thread screw for timber, and a fine-thread screw for metal.

Self-tapping or self-drilling: match the screw to the steel

  • Standard studs and track (under 0.8mm steel): British Gypsum Drywall Screws. They're black phosphate coated with a sharp self-tapping point. A standard 70 S 50 stud is 0.5mm steel, so this is the screw for most metal stud partitions. (Siniat calls this its Self-Tapping Drywall Screw.)

  • Heavier framing (0.8mm and over): British Gypsum Jack-Point Screws, which have a self-drilling tip and are zinc plated. They're also the screw for Gypframe I Studs 0.6mm thick or more. Jack-Point lengths are 25, 35, 41 and 60mm. (Siniat's Self-Drilling Drywall Screw covers 0.8mm to 2.5mm.)

  • Metal to metal: 13mm wafer head screws. The low head sits flat, so the board goes on without bumps. British Gypsum makes a Wafer Head Drywall Screw for steel under 0.8mm and a Wafer Head Jack-Point for 0.8mm and over (Siniat makes 12mm and 13mm wafer heads). British Gypsum uses them to splice studs and to fix the channel at door openings.

Special boards need their own screws

  • Gyproc Habito: British Gypsum High Performance Screws (Siniat uses its Performance screws for LaDura, Megadeco and Universal Board).

  • Rigidur H: Rigidur Screws, 30mm and 40mm.

  • Glasroc X sheathing on SFS: Glasroc X Screws, 25mm, for steel up to 2.5mm.

  • Glasroc F FireCase: FireCase Screws, made for board-to-board fixing.

  • Wet areas: Siniat makes ceramic-coated Wet Area screws for wet areas and external use.

Where the screws go

  • Edges: at least 10mm in from a paper-bound edge and 13mm from a cut edge, and at least 3mm in from the edge of the metal profile (Siniat).

  • Centres on partitions: 300mm, closing to 200mm at external angles (Knauf and Siniat also work to 300mm).

  • Centres on ceilings: 230mm across the field of the board and 150mm at board ends (Siniat also uses 150mm at the perimeter and cut edges).

  • Encasements: 150mm centres.

  • Centres can change with the system, so check the specification for the one you're building.

  • Depth: drive the head just below the board surface, then spot it with jointing compound (Siniat).

  • Resilient bar: screw into the bar only. A screw that touches the stud behind it carries sound straight through (British Gypsum and Siniat). In British Gypsum's GypWall Single Frame Enhanced, screws must not go into the web of the stud either.

Ordering screws

Box sizes change with length. British Gypsum's 25mm Drywall Screws come in boxes of 1,000, the 50mm in 500s and the 90mm in 250s. Collated screws generally come in strips of 50 for autofeed guns (Siniat boxes hold 500 or 1,000, depending on the screw). Check the box quantity before you work out how many boxes to order, and add your waste allowance. Our free Drylining Waste Guide gives the figure for screws and fixings.

For the board itself, see how many sheets of plasterboard do I need.

Get the free Drylining Waste Guide

Waste allowances for plasterboard, metal stud, track, insulation, screws and fixings, jointing compound and tape, plus five rules for ordering.

Common questions

What size screws for 12.5mm plasterboard?

Use 25mm screws into metal studs. 12.5mm of board plus 10mm into the steel needs 22.5mm. Into timber you need at least 37.5mm, so 38mm or 40mm depending on the brand.

Are 32mm or 38mm screws OK for plasterboard?

A 32mm screw works for one layer of 12.5mm or 15mm board on metal. A 38mm screw covers 2 x 12.5mm and 12.5mm + 15mm on metal. For 2 x 15mm you need at least 40mm, so a 38mm screw is too short.

What screws do you use for metal studs?

Use self-tapping drywall screws for standard studs and track under 0.8mm thick, and self-drilling screws (British Gypsum calls them Jack-Point) for heavier steel 0.8mm and over.

What length screw for double-layer plasterboard?

The inner layer takes the single-layer screw, usually 25mm. The outer layer needs both boards plus 10mm: 35mm for 2 x 12.5mm and 40mm for 2 x 15mm with British Gypsum screws.

Figures are from manufacturers' published information and are for guidance. Screw type, length and centres depend on the system, the board and the fire and acoustic requirements. Always build to the specification and the manufacturer's current literature.

Can you use the same screws in timber and metal?

British Gypsum's Drywall Screws from 35mm up are rated for both. Siniat uses fine thread for metal and coarse thread for timber. Check the length either way: timber needs 25mm of grip against 10mm for metal.

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Sources

  • British Gypsum product data sheets: Drywall Screws (25 to 120mm), Jack-Point Screws, Wafer Head Drywall and Jack-Point Screws, High Performance Screws, Rigidur Screws, Glasroc X Screws, Glasroc F FireCase Screws (18 January 2024; Glasroc X 22 May 2025)

  • British Gypsum Technical Support FAQ: What are the screw fixing centres for partitions, ceilings and encasements?

  • British Gypsum White Book: GypWall Single Frame Enhanced and resilient bar construction details (2026)

  • Knauf Partitions Manual and Knauf Drywall Manual: Installation Procedures

  • Siniat Drywall Manual, annexes (v1.1.0, July 2022): screw selection guide and GTEC Drywall Screws

  • Siniat technical datasheet: GTEC Drywall Screws (2020)