Wall insulation
Insulating your walls could cut your heating costs considerably. Did you know solid walls let through twice as much heat as cavity walls do? The good news is they can both be insulated.
Choosing wall insulation:
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.
If you live in a house that has a non-traditional construction such as a concrete, steel or timber-framed building, insulating will be different. Find out more from the National Insulation Association.
Solid wall insulation
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.
Keeping the costs of installing solid wall insulation down
The costs we reference for installing solid wall insulation are for paying a company to come in, insulate your whole house in one go, fully redecorate and replace everything just as it was. Some people want exactly this, but it does cost a lot of money.
If you’re looking to spend less, it is advisable to insulate a wall when you are having other building or decorating work done. Fitting the insulation work in with your other home improvements not only saves money on the job, it also spreads the cost of the insulation as you improve your home’s rooms.
External insulation will also cost less if you do it when you’re having other work done to the outside. If you’re having a new roof, or painting the windows, or even having solar PV panels fitted, then you will probably have scaffolding up already, which can save a bit on the costs. If you have rendered walls with damaged render, or brick walls that need re-pointing, external insulation may not cost you much more than you would need to pay for the repairs.
Internal wall insulation is done by fitting rigid insulation boards to the wall, or by building a stud wall filled in with insulation material such as mineral wool fibre.
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.
Moisture movement and ventilation
In traditionally built properties with solid walls, it is recommended to use breathable (also known as vapour permeable) solid wall insulation materials as these allow continuous movement of air (vapour) and this helps reduce the possibility of moisture build up.
If you are planning on installing non-breathable (also known as vapour impermeable) solid wall insulation materials in a traditionally built property then we recommend you ask the installer what consideration needs to be given, if anything, to avoid the build-up of moisture in your home.
Remember to check with your installer that the installation is covered by the SWIGA guarantee which gives 25 years cover for defective materials, design or workmanship or by other appropriate guarantees such as Kinnell ECO Guarantee (which covers most of natural building technologies). Also check with your installer that the products/materials are BBA certified.
Cavity Wall Insulation
Up to a third of all heat in an uninsulated home escapes through the walls — which means you’re paying for warmth that simply disappears. Cavity wall insulation fills the gap between your home’s inner and outer walls, creating a barrier that prevents heat from escaping and stops cold air from getting in. The result is a warmer, more energy-efficient home that costs less to heat.
Installing cavity wall insulation is one of the most effective and affordable ways to reduce your energy costs. Most homeowners notice immediate savings on their heating bills and a more consistent, comfortable indoor temperature throughout the year.
But the benefits go beyond cost savings. A properly insulated home also helps lower your carbon footprint, reducing the amount of energy you need to stay warm — and that means fewer emissions released into the environment. Plus, maintaining a stable temperature can have a positive impact on your well-being, helping to prevent damp, reduce condensation, and create a healthier living space for you and your family.