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	External cladding
	Solid blockwork wall
	Polyfoam Linerboard
	Plaster adhesive dabs

Polyfoam Linerboard is a laminate of Polyfoam high performance, 100% ozone friendly, extruded polystyrene, rigid board insulation and 9.5mm tapered edge plasterboard.

 

New or existing masonry solid walls, lined internally with Polyfoam Linerboard. Polyfoam Linerboards can be fixed with adhesive, plaster adhesive dabs or mechanically fixed. Where dabs or adhesive are used, secondary mechanical fixings are needed to secure the plasterboard in case of fire.

 

Before fitting the dry lining, the ceiling lining should be in place. The surface to be lined should be clean and dry with all wallpaper and loose plaster removed. If heavy fixtures, such as wash basins, are to be fixed to the wall, timber battens should be provided to accept the fixings. Holes for services should be cut before fixing the board. To accommodate services or obstructions on the wall, cut away the insulation to the depth of the obstruction. Boards can be either cut or sawn. When cutting the boards, use a sharp knife to cut through the insulation and score the board. The score is then snapped open to give a clean edge.

Adhesive fixing

Where the walls are even with a sound plaster finish, Polyfoam Linerboard can be fixed directly with plaster or cement based adhesives. The adhesive is applied in vertical bands at the board edge and down the centre of the board. Bands of adhesive should also be applied around openings, service penetrations and at the junctions with ceilings and floors. This is to reduce air infiltration.

Plaster adhesive dabs

Where the wall is uneven, such as unplastered blockwork, the boards should be fixed by means of plaster adhesive dabs. Again, there should be a continuous band of plaster adhesive around the perimeter of each wall area to minimise air infiltration. Offer the board to the wall and adjust with a footlifter as necessary. Insert packing strips at the base. Tap the board to align with pre-determined guidelines and adjacent boards. A neat and close line should be achieved at the wall/ceiling junction. Fill any gap at the base with proprietary bonding compound or sealant. When fixing Polyfoam Linerboard with adhesive or dabs, secondary mechanical fixings are required. Two fixings are recommended at the top of each board, 25mm in from the edge. The fixings should penetrate at least 35mm into a solid background. All PVC insulated electrical cables should be run in trunking or conduit behind the dry lining to avoid direct contact with the insulation.

 

The insulation element of Polyfoam Linerboard has a thermal conductivity of 0.030 W/mK and the plasterboard has a thermal conductivity of 0.19 W/mK. The table below gives U-values for typical constructions.

Typical U-values (W/m²K) for solid masonry walls dry lined with Polyfoam Linerboard

Polyfoam Linerboard thickness (mm)	U-value (W/m2K) for 215mm Solid masonry wall of:
	Dense block (λ=1.13)	Medium block (λ=0.51)	Lightweight aggregate (λ=0.34)	Standard aircrete (λ=0.16)	Lightweight aircrete (λ=0.11)	Brick (λ=0.77)
72.5/9.5	0.34	0.32	0.30	0.26	0.23	0.33
45.5/9.5	0.48	0.44	0.41	0.33	0.29	0.46
36/9.5	0.57	0.51	0.46	0.37	0.32	0.54
30.5/9.5	0.63	0.56	0.51	0.40	0.34	0.60

Note: The U-values have been calculated to BS EN ISO 6946: 1997 and assume a 19mm sand cement render external finish.

Fire performance

Polyfoam Linerboard consists of a 9.5mm plasterboard which offers excellent fire performance as a facing material and Polyfoam insulation which contains a flame retardant to inhibit localised ignition. When installed on dabs the secondary fixings at the top of each board will ensure the integrity of the application during evacuation in case of fire.

 

The rigidity of the Polyfoam board behind the plasterboard will offer an excellent support to the finished internal lining and assist in the resistance of impact damage, helping to prolong its service life.

Moisture resistance

Walls should be sound and weatherproof before applying a thermal plasterboard laminate. Damp walls could have a detrimental effect on insulation and adhesive performance. When lining internal walls in refurbishment projects the existing wall is often in a state of disrepair, which can mean dampness. The Polyfoam insulation backing to the plasterboard is resistant to moisture absorption and can offer the best peace of mind solution for an application where, as outlined above any potential moisture ingress is a concern. If in any doubt about adhesive use mechanical fixings.