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    Insulating the loft

    Insulation is the first line of defence in the fight against high energy bills, for around half the heat lost in a typical home escapes through the walls and the roof. It is estimated that around 25% of heat is lost through an un-insulated loft, costing the average household £155 per year. And although the sparrows perched on your roof will have warm feet, they won’t be contributing towards your heating bills.

    Image supplied by North Cornwall District Council

    Image supplied by

    Fortunately, a number of easy to install loft insulation materials are available to remedy this problem. These will either come in the form of rolls of blanket insulation or in bags of loose-fill insulation, both of which are laid between the joists.

    Blanket insulation is made from mineral wool and is available in large rolls. Although an effective insulation material it can cause skin irritation and care should be taken when laying this material. Today there are a number of alternatives to mineral wool including sheep’s wool and recycled plastic bottles. This highlights the growing demand for building materials that are ecologically friendly as well as providing a cost effective solution.

    Loose fill insulation comes in bags and is poured between the ceiling joists. The most common type of loose-fill insulation is vermiculite granules (a crushed igneous rock); other materials used for this form of insulation are cork granules, mineral wool and cellulose fibre.

    Whatever insulation material you choose it is crucial to lay it at the correct thickness to achieve maximum thermal efficiency. The Energy Saving Trust – a non-profit organisation set up to promote the efficient use of energy – recommends a thickness of 270mm for all loft insulation.

    Many homeowners already with loft insulation may find it has been laid at a thickness well short of this figure. One reason for this is that in the past it was considered adequate to install insulation to the top of the ceiling joists, which would achieve a thickness of 100mm to 150mm.

    If the blanket insulation in your loft is not the correct thickness, simply add another layer or layers of insulation until the recommended thickness of 270mm is achieved. Shallow ceiling joists, however, present a different problem if loose fill insulation has not been installed to the correct depth. To create the required depth of 270mm it will be necessary to fix lengths of timber to the top of the joists. Once again this is not a difficult job and well within the capabilities of anyone with even limited DIY experience.

    Next: Cavity wall insulation