Wall Insulation

Insulating your solid walls could cut your heating costs considerably, because solid walls let through twice as much heat as cavity walls do. The good news is they can be insulated.

If your home was built before 1919, its external walls are probably solid rather than cavity walls. Cavity walls are made of two layers with a small gap or ‘cavity’ between them. Solid walls have no gap, so they let more heat through.

Another way to tell is by measuring the width of the wall. Look at an external wall window or door and if the brick wall is less than 260mm, then it is likely a solid wall, while if it is greater, it is probably a cavity wall. Find out about insulating your cavity wall.

Solid walls can be insulated – either from the inside or the outside. This will cost more than insulating a standard cavity wall, but the savings on your heating bills will be bigger too.

Internal wall insulation:

• is generally cheaper to install than external wall insulation
• will slightly reduce the floor area of any rooms in which it is applied (the thickness of the insulation is around 100mm)
• is disruptive, but can be done room by room
• requires skirting boards, door frames and external fittings to be removed and reattached
• can make it hard to fix heavy items to inside walls – although special fixings are available
• needs any problems with penetrating or rising damp to be fixed first.

External wall insulation:

• can be applied without disruption to the household
• does not reduce the floor area of your home
• renews the appearance of outer walls
• improves weatherproofing and sound resistance.
• fills cracks and gaps in the brickwork, which will reduce draughts
• increases the life of your walls by protecting the brickwork
• reduces condensation on internal walls and can help prevent damp (but will not solve rising or penetration damp)
• is best installed at the same time as external refurbishment work to reduce the cost
• may need planning permission - check with your local council
• requires good access to the outer walls
• is not recommended if the outer walls are structurally unsound and cannot be repaired.