Wall and ceiling finishes

9.2

9.2.4Dry lining

Dry lining shall provide an adequate substrate for the decorative finish. Issues to be taken into account include:

  1. installation
  2. vapour control
  3. detailing and support
  4. fixing.

Installation

Dry lining should:

  • not be started until the building is substantially weatherproofed
  • 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.

Table 4: Standards relevant to dry lining

BS EN 520‘Gypsum plasterboards. Definitions, requirements and test methods’
BS 8212‘Code of practice for dry lining and partitioning using gypsum plasterboard’.

Vapour control

Vapour control layers should be used to reduce the risk of interstitial condensation, and be installed in accordance with:

  • Chapter 6.2 ‘External timber framed walls’
  • Chapter 7.1 ‘Flat roofs and balconies’
  • Chapter 7.2 ‘Pitched roofs’
  • Chapter 7.10 'Light steel framing'.

Detailing and support

Support should be provided to plasterboard in accordance with Table 5.

Table 5: Frequency of support for plasterboard

Board thickness (mm)Maximum timber support centres (mm)Intermediate noggings requiredPerimeter noggings required
9.5400NoYes
450YesYes
12.5400NoYes
450NoYes
600YesYes
15600NoYes*

* unless floor joist manufacturer's or plasterboard manufacturer's guidance state that no perimeter noggings are required.

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 vapour control layers should be taped and sealed)
  • ceiling boards should be staggered to minimise any risk of cracking.

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 plasterboard nails or 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.

Nails or 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 6: Acceptable fixing centres and fixings

FixingLocation and spacingCoating
NailWalls and ceilings: approximately 150mm centres (eight per linear metre)Hot dip galvanised, zinc electroplated or sheradised steel
ScrewCeilings: approximately 230mm centres (eight per two linear metres)
Walls: approximately 300mm centres (five per linear metre)		Zinc electroplated or black phosphate (or to the board manufacturer’s recommendations)

Table 7: Acceptable fixing lengths

Board thickness (mm)Nail length (mm)Screw length (mm) into timberScrew length (mm) into steel
9.5303222
12.5403622
15403625

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 centers measured vertically, each dab should be 50 mm to 75 mm wide and approximately 250 mm long and in accordance with Table 8.

Table 8: Dabs according to board dimensions

Thickness of wall board (mm)Width of wall board (mm)Dabs per board (rows)
9.59003
9.512004
12.512003

Dry lining to receive ceramic wall tiling should be supported in accordance with Table 9 or the guidance given in BS 8212.

Table 9: Board fixing guidance for walls to receive ceramic tiles