Costed: Insulation - March/April 2014

Jonathan White, executive consultant in Gleeds’ R&D team, gives an overview of the costs associated with thermal insulation

A high standard of thermal insulation to buildings provides various benefits.

Most obviously, it reduces the rate of heat loss through the building fabric, cutting energy consumption and reducing  heating costs. It also increases internal surface temperatures, reducing the risk of condensation.

Among the many thermal insulating materials available, four types are most commonly used.

Mineral fibre is used to insulate empty lofts, under suspended timber floors and for stud walls.  For horizontal use the product comes in a roll form which can be laid loose between rafters.  For walls a more rigid batt enables vertical fixing.  

Rigid boards are used to line the inner skin of the building envelope.  It is important to avoid air gaps between the inner skin and the board for it to achieve maximum performance.

Loose fill material, made of cork granules, vermiculite, mineral wool or cellulose fibre, is used for lofts and is ideal for irregular spaces.

Cavity fill can be mineral or cellulose fibre or plastic granules, which is blown into the cavity after construction is completed.  Care must be taken to avoid the creation of voids resulting from obstructions in the cavity. This method of insulation can also be used effectively on existing buildings.

Any product’s thermal conductivity, or K-value, can be used to calculate the appropriate material and thickness to achieve the ­required performance.

The rates stated below represent a guide to insulation installation costs and are current at the first quarter, 2014 (vat is excluded).  They have been derived from Gleeds’ cost database supported by published material, and reflect rates typically submitted through competitive tenders. No allowance is made for sundry costs or related preliminaries costs.