Home Insulation Methods and Advice

Glass fibre

Where joists run at even widths, glass-fibre matting can be laid between or over the joists. This can be cut with household scissors. Protective gloves should be worn as minute glass-fibre particles may irritate the skin.

Rolls of insulant matting are made in various lengths and, when laid, should be 25mm at least wider than the space between joists so that no part of the ceiling is left exposed.

When laying the matting over joists, use lm wide matting and overlap the edges by at least 75mm. Drape the matting over the end of the joists to prevent draughts getting underneath.

Loose fill

Expanded polystyrene, mineral wool, vermiculite and cork are obtainable as loose-fill materials in particle or in pellet form.

These are poured between joists to a depth of about 50mm. As the material is poured, it should be raked level with a timber template cut to the depth and width of the joist space. Do not compress the material.

The ends of the joists can be sealed with building paper but do not block any air vents as this may cause condensation. Once laid, loose-fill material is quite stable.

Mineral wool

Mineral wool is available in semi-rigid slabs which can be laid between joists. The depth of insulation depends on the type of home heating you have.

The more heat produced in the house, the more is lost through the roof space, and, therefore, the greater depth of insulation needed.

Foil-backed lining

The second method is to insulate the gaps between rafters. Attach foil-backed insulating felt or bitumen-backed paper between the rafters. Apart from cutting down on heat loss, this will help to keep the roof area clean. Slabs of expanded polystyrene can be placed between the rafters.


It is important to realise that if you insulate the floor of the roof space you then create a much colder roof area. The warm air from the house is no longer rising to fill the space.

Therefore, it is important to lag all pipework and plumbing services located in the loft. Pipe coverings are made to fit standard pipe sizes.

They are either rigid, of glass fibre, cork, mineral wool or expanded plastic, or flexible, of synthetic rubber, expanded polystyrene or foamed polyurethane. These ‘sleeves’ fit round the pipework.

Each section should be overlapped, taking care that joints and entry points to the storage cistern are covered.

Such lagging materials can be cut with scissors and secured at intervals with tape or string.

Cisterns and hot-water cylinders should be insulated. Lagging sets consist of panels of expanded polystyrene, compressed in-sulant board or glass-fibre jackets.

Another method of insulating a cistern is to construct a case of chipboard, leaving a 50mm-70mm gap round the sides and at the top, filling the space with loose-fill insulant material.

Do not put insulant materials under the cold-water storage cistern. The trickle of heat from below will avoid freezing when the outside temperatures fall.

Any pipes positioned between the joists can be covered with loose-fill material or matting.

10. November 2011 by admin
Categories: Featured, Handyman Tips | Tags: , , , , , , , , , | Comments Off on Home Insulation Methods and Advice


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