Installing wall insulation will significantly reduce heat loss, with 35% of an uninsulated building’s heat loss occurring through the walls. As the external walls make up the majority of the building envelope and are directly exposed to the colder external temperatures, it is essential to insulate the walls using high performance insulation materials, such as PIR insulation boards, in order to combat this heat loss.

Cavity walls are where the external wall is constructed of two masonry walls with a gap, or cavity, between the two structures, which are tied together by metal ties. The cavity is where the insulation is installed in this type of wall, and there are a number of installation methods depending on the wall construction.

Solid wall construction, which is commonly found in older buildings, will allow more heat loss than cavity wall construction. In retrofit projects, adding internal insulation to the external solid wall will result in the most significant reduction in heat loss and a vast improvement in the comfort levels of the building. Internal wall insulation on solid walls can be fixed using battens or dabs.

PIR insulation boards are among the most commonly used wall insulation materials due to their excellent thermal properties and ease of fitting and handling. Wall insulation boards like Mannok Therm Wall / MW and Mannok Therm Cavity / MC Insulation are specifically designed to suit wall applications and boast excellent thermal conductivity of 0.022w/mK.

Mannok IsoShield is a superior full fill insulation product which is designed for cavity wall applications. This full fill insulation board is easy to cut and fit, with exceptional thermal properties, and can reduce cavity width and build cost without compromising on the thermal performance of the building.

The rigid insulation boards are faced on both sides with a low emissivity composite foil facing. This feature increases the thermal resistance of an unventilated cavity adjacent to the insulation, reducing the rate of heat loss through the wall and subsequently reducing the overall U-value of the wall.

Thermal bridging in wall construction can also occur at the key wall to floor and wall to roof junctions and where fixings are used.

The selection and specification of appropriate fixings are key considerations in achieving efficient wall insulation systems. Designers must consider both the thermal and mechanical performance of the fixings. To combat thermal bridging at the key wall junctions, designers should ensure there are no breaks in the insulation, which in some cases will require the wall insulation boards to extend beyond the junction.

PIR insulation boards boast good dimensional tolerances, which enables the insulation to be butted tightly together to form a continuous layer of insulation, whether you are using the straight edge insulation boards, or the profiled tongue and groove edged boards.

This continuous layer of insulation is important to ensure no thermal bridging occurs through gaps in the insulation, and the rigid, well-fitting design of wall insulation boards ensures this can be easily avoided.