External Wall Insulation

If your home was built before 1920, there is a strong likelihood that the outside walls will be solid rather than cavity walls.

Unlike cavity walls (that consist of two layers with a small gap or ‘cavity’ between them), solid walls have no such gap, which means they let more heat through. Solid walls can be insulated either from the inside or the outside.

Internal wall insulation involves either fitting rigid insulation boards to the wall or building a stud wall filled in with mineral wool fibre.

Although this method tends to be slightly cheaper than external wall insulation (EWI), it’s worth bearing in mind that the thickness of the insulation is around 100mm so it will slightly reduce the floor area of the rooms in which it’s applied.

Skirting boards, door frames and external fittings need to be removed prior to installing internal wall insulation, and any problems with penetrating or rising damp need to be addressed first.

External wall insulation involves fixing a layer of insulation material to the wall, which is then covered with a special type of render or cladding. The finish can be smooth, textured, painted, tiled, panelled, pebble-dashed, or finished with brick slips.

This method can be applied without causing any disruption to the household, and, unlike internal wall insulation, won’t reduce the floor area of your home. It will not only renew the appearance of outer walls, but also improves weatherproofing and sound resistance, fills cracks and gaps in the brickwork (reducing drafts), reduces condensation on internal walls and can help prevent damp.

External wall insulation requires good access to outer walls, and is not recommended if the outer walls are structurally unsound and cannot be repaired.


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