Home Insulation: Floors and Roofs


Floors are of two types: suspended floors, timber-boarded floors laid on joists, or solid concrete laid on to a waterproof membrane. In some very old properties the floor may be laid directly on to subsoil.

A suspended floor has a ‘U’ value as high as 2.71 and can be a considerable area of heat loss. There must, of course, be underfloor ventilation to combat timber decay, but draughts blow up through badly fitting floorboards and gaps between the skirting and floorboards.

If you have to lift floorboards to fit central-heating pipe runs or electrical wiring, a quilt of 13mm insulating material or aluminium foil-backed paper can be laid across the joists to provide an insulant layer.

The entire floor may be covered with hardboard if floorboards are unlikely to be lifted frequently. This not only excludes draughts but provides the necessary first base needed for many floor coverings.

Any gap between skirting and floorboards may be filled with a piece of quadrant fixed firmly to the floor-not to the skirting board as there may be floor movement.

Large gaps between boards can be filled with thin pieces of wood or with a proprietary cellulose filler mixed with a little PVA adhesive. This can be rubbed down when dry and stained to match the boards.

Even folded pieces of newspaper pushed between gaps in floorboards will cut draughts and improve insulation.

Solid floors have a lower ‘U’ value-0-20. Additional comfort can be gained by careful choice of carpeting. Use the best-quality underlay and the thickest carpet you can afford or, possibly, one of the newer foam-backed vinyl floor coverings.

‘U’ values

These are the ‘U’ values of various types of floors:

• Wood floors on joists: 2.71 to 1.42

• Parquet or lino over floorboards on joists: 1.42

• Thermoplastic tiles on concrete: 1.13

• Wood blocks on concrete: 0.85

Roof space

There are two ways of insulating the loft space. You can either insulate between the joists on the floor of the roof space or between the rafters on the ceiling of the area.

Unless you wish to use the loft space as a work room or it is to be converted for extra living space, the easier method is to lay insulant material between the joists.

Polystyrene, slab or granulated, vermiculite fill, eel-grass, mineral wool, glass fibre, felted wool or vegetable fibre and cork, compressed in slab form or in particles can be used.

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


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