Dry Lining Insulation

Internal insulation (commonly referred to as 'dry-lining walls') involves fixing insulation to the inner surfaces of your external walls and covering it with a vapour barrier layer and plasterboard or, alternatively, composite boards of plasterboard backed with insulation and incorporating a vapour barrier.

Types of insulation material used include expanded polystyrene, fibreglass and polyurethane boards. Polyurethane tends to be more expensive, but its thermal performance is better than polystyrene or fibreglass, so a 25 mm (1 inch) thickness of polyurethane will have roughly the same insulating performance as a 38 mm (1.5 inch) thickness of polystyrene.

Condensation that may occur on the walls is prevented by installing a vapour barrier on the warm i.e. room side of the insulation. Composite boards for internal insulation generally incorporate a vapour barrier. It is important that the vapour barrier be well sealed at wall, floor, ceiling, door and window junctions, around light switches and at all other breaks in the insulation.

Homeowners availing of any wall insulation grants under the Home Energy Savings scheme should aim to achieve a U-value of 0.27 W/m K or better (i.e. lower).