External Walls: Internally applied flexible insulated linings

Description

Flexible latex foam thermal lining with resilient glass fibre mat facing which can be applied to internal surface of walls, normally to combat surface condensation and mould growth. Thickness 10 mm.

Unit cost of installation

£2,200

Bulk cost of installation

Data not available

Indicative cost and carbon saving

The above data assume a resulting U value for the wall of 1.58 W/m²K, and a foam thickness of 10 mm.

Maintenance

None normally required.

Lifetime

The lining itself will have a lifetime similar to other linings such as plasterboard. Lifetime of the system will depend to a certain extent on the quality of workmanship, preparation etc.

Technical suitability

Compressibility may mean that difficulties may be encountered when fixing some items to walls. Application of latex foam liner will be less disruptive to tenants than 'normal' internal insulation, but it is not as cost effective - payback times will be longer for 10mm latex foam, and savings on fuel bills lower compared to internal insulation. The thinner (5mm) products are intended only as a measure to combat condensation. This technology would however need to be used in conjunction with other insulation methods to achieve the requirements of current building regulations.

Detailing around external door and window frames can be difficult and if not dealt with effectively can lead to a lowering of surface temperature adjacent to the window or door frame and a consequent increased risk of condensation in those areas (although generally flexible thermal linings greatly reduces the risk of surface condensation). A similar situation can occur where internal separating walls and floors meet external walls. To avoid the problem the insulation should be returned for a short distance along the separating wall, and on the underside of solid intermediate floors. The upper faces of solid floors are more difficult to treat, and may benefit from the addition of composites to provide a floating floor (see floor insulation). Suspended floors can be insulated near the wall with fibrous insulation, but it would be difficult to incorporate a vapour barrier in this situation.

Care needs to be exercised to ensure that air bricks are not blocked, and internal fixtures and fittings (radiators, electrical sockets, skirting boards etc.) may need to be removed prior to installing the lining and subsequently re-fixed. The lining should ideally extend behind the skirting boards to within 5mm of floor to avoid cold bridges behind the skirting. Any penetrating or rising dampness should be dealt with before treating the walls.

Because the lining is applied internally some of the thermal mass of the structure is isolated from the internal atmosphere. This will tend to increase the responsiveness of the heating system, but also slightly increase fluctuations in indoor temperatures over a complete daily heating cycle.

Potential concerns with fuel poor

No specific issues.

Ancillary benefits

Linings are relatively thin (5 - 10mm thick), so there will be a much lower reduction of useable floor space compared to internal insulation and can be used in conjunction with standard internal insulation when the greater thickness of the latter presents a problem.

The thinner (5mm) versions are intended mainly to combat condensation and mould growth, which will have beneficial impact on occupants health.

Trigger points for work

Remedial works to combat condensation. Redecoration works.

(N.B. Building Regulations Approval is required in England & Wales whenever any thermal element is renovated, and a U-value of 0.35W/m²K would normally be required. However a lesser standard may be acceptable if it is not technically or functionally possible to achieve this U-value).

Technical Guidance Available

National Insulation Association (NIA) 01428 654011 http://www.nationalinsulationassociation.org.uk/