9.2.4 Dry lining
Dry lining shall provide an adequate substrate for the decorative finish. Issues to be taken into account include:
- installation
- air and vapour control (AVCL)
- detailing and support
- fixing.
Installation#
Dry lining should:
- not be started until the building is substantially weatherproofed
- not be started until structural timber components are at a moisture content of 20% or less
- be programmed so that finishes are applied as soon as possible after completion
- provide performance in accordance with Building Regulations where it contributes to fire resistance
- ensure that gap sealing is specified where necessary to prevent draughts.
- be appropriate for the application, eg be moisture resistant to walls and ceilings in bathrooms and ensuites.
Table 4: Standards relevant to dry lining
| BS EN 520 | ‘Gypsum plasterboards. Definitions, requirements and test methods’ |
| BS 8000-8 | 'Workmanship on construction sites. Design and installation of dry lining systems – Code of practice’ |
Air and vapour control (AVCL)#
Air and vapour control layers should be used to reduce the risk of interstitial condensation and enhance air tightness, and be installed in accordance with:
- Chapter 6.2 ‘External timber framed walls’
- Chapter 6.10 'Light steel framing'
- Chapter 7.1 ‘Flat roofs and balconies’
- Chapter 7.2 ‘Pitched roofs’.
Detailing and support#
Support should be provided to plasterboard walls and ceilings in accordance with Tables 5 and 6. Where walls are to receive ceramic tiling, additional support may be required, see Table 10.
Table 5: Frequency of support for plasterboard to walls
| Board thickness (mm) | Maximum timber support centres (mm) |
|---|---|
| 9.5 | 450 |
| 12.5, 15 & 19 | 600 |
Table 6: Frequency of support for plasterboard to ceilings
| Board thickness (mm) | Maximum timber support centres (mm) | Intermediate noggings required(1) | Perimeter noggings required(1) |
|---|---|---|---|
| 9.5 | 400 | No | Yes |
| 450 | Yes | Yes | |
| 12.5 & 15 | 400 | No | Yes |
| 450 | No | Yes | |
| 600 | Yes | Yes | |
| 19 | 600 | No | No |
Notes
1. Alternatively, the spacing of studs and joists, the requirements for intermediate and perimeter noggings, and any additional support battens should be in accordance with the plasterboard or system manufacturer's installation instructions or fire test evidence, or applicable industry guidance documents.
When fixing boards:
- damaged boards should not be used
- they should be fixed face side out, appropriate for plastering or directly applied finishes
- cut edges should finish over a support or nogging (though are permitted, where necessary, at perimeters)
- there should be adequate support for light points, socket outlets and other service installations
- openings for services and electrical outlets should be accurately cut (gaps in the air and vapour control layers should be taped and sealed)
- ceiling boards should be staggered to minimise any risk of cracking
- where metal resilient bars are installed to ceilings, additional resilient bar perimeter noggings should be installed in accordance with the manufacturer’s installation instructions and/or supporting fire test evidence.
Joints between boards should be neatly formed, flush, and suitably finished:
- with scrim tape or paper tape, where boards are to be plastered
- with tape, and filled, where boards are not to be plastered (tapered edge boards should be used for directly applied finishes), or
- as recommended by the manufacturer.
Where double layers of plasterboard are used, they should:
- be positioned so joints are staggered between layers
- have the first layer fully fixed and have all cut edges supported
- have the second layer supported on all edges with noggings provided to suit.
Dry lining should be:
- completely taped and filled at board joints and at the abutments to ceilings and internal walls
- finished to an appropriate standard and in accordance with Chapter 9.1 ‘A consistent approach to finishes’.
Fixing#
Plasterboard should be fixed to:
- timber using dry wall screws
- metal using dry wall screws, or
- masonry using adhesive dabs.
Where insulated dry lining is used, nailable plugs should be specified in accordance with the manufacturer’s recommendations, and at a minimum of two per board.
Screws should not project above the board surface and should be:
- 10mm minimum from paper-bound edges
- 13mm minimum from cut ends of boards
- 6mm minimum from edges of timber members.
Table 7: Acceptable fixing centres
| Fixing | Location and spacing | Coating |
|---|---|---|
| Screw | Ceilings: approximately 230mm centres (eight per two linear metres) within the field of the plasterboard, and 150mm at plasterboard ends and ceiling perimeters Walls: approximately 300mm centres (five per linear metre), and 200mm on external corners and around openings | Zinc electroplated or black phosphate (or to the board manufacturer’s recommendations) |
Table 8: Acceptable fixing lengths
| Board thickness (mm) | Screw length (mm) into timber | Screw length (mm) into steel |
|---|---|---|
| 9.5 | 35 | 25 |
| 12.5 | 38 | 25 |
| 15 | 40 | 25 |
| 2 x 12.5 | 50 | 35 |
| 2 x 15 | 60 | 40 |
| 1 x 12.5 & 1 x 19 | 57 | 42 |
Where walls or ceilings require fire resistance, fixings should be installed in accordance with the plasterboard or system manufacturer’s fire test evidence.
Where dry lining is fixed with adhesive dabs, it should be:
- securely fixed and filled at external and internal corners, including door and window openings
- filled with jointing compound where required, at gaps around service points, electric sockets, light switches, etc.
- installed with a continuous ribbon of adhesive to the perimeter of external walls, and around openings and services, to prevent air infiltration.
Adhesive dabs should be at 300mm centres measured vertically, each dab should be 50 mm to 75 mm wide and approximately 250 mm long and in accordance with Table 9.
Table 9: Dabs according to board dimensions
| Thickness of wall board (mm) | Width of wall board (mm) | Vertical rows of dabs per board |
|---|---|---|
| 9.5 | 1200 | 4 |
| 12.5 | 1200 | 3 |
| 15.0 | 1200 | 3 |
Dry lining to receive ceramic wall tiling should be supported in accordance with Table 10 or the guidance given in BS 8000-8.
Table 10: Board fixing guidance for walls to receive ceramic tiles
Last updated: 2nd January 2024