What is solid wall insulation?
Solid wall insulation is a process whereby fixed heat-retentive walls or boards are applied to either the interior or exterior walls of your home to help prevent heat escaping. It's estimated that twice as much energy escapes through solid walls compared to cavity walls, and savings in the region of £455* can be made on annual fuel bills upon installation.
How do I check if my home has solid walls?
Most properties built before 1920 have solid external walls, according to the Energy Saving Trust. Heat passes through solid material at a faster speed than through a gap - so solid walls lose heat more quickly than cavity walls.
You can also measure the width of the wall to check. If the brick wall measures less than 260mm, it's likely to be a solid wall.
How to insulate solid walls
It's more complicated to insulate solid walls than cavity walls. This must be done from the inside or outside, as you cannot simply fill a cavity with a material that will stop heat escaping.
If the work is done internally, rigid insulation boards will be fitted to the walls. Alternatively, a 'stud' wall may be built and filled in with mineral wool fibre.
Externally, a layer of insulation material will be fixed to the wall, and covered with a special type of plaster or cladding.
The option you pick depends on your budget, and your property. Bear in mind there is likely to be some disruption while the work is done. It may be easier and cheaper to get walls insulated while making other big home improvements, such as fitting a new kitchen.
How much does it cost?
External solid wall insulation is typically more expensive than insulating from inside.
The total cost of paying a company to install external solid wall insulation ranges from £8,000 to £22,000, according to the Energy Saving Trust. Internal insulation costs from about £3,500 to £14,500.
The reason for the price difference is the amount of work required. Also, external wall insulation has the advantage of being applied without disruption to the household, and doesn't reduce the floor area of your home.
How much will I save?
Installing external or internal wall insulation will slash a typical detached household's annual bill by around £455 a year. The bill for a flat would be cut by around £145 a year. So it can take decades to recoup the sum spent, but if you plan to stay in your home for a long time this could be worthwhile.
Is any help available towards the cost?
Local authorities and energy providers may offer some assistance with the cost.
Make sure the work complies with current Building Regulations, and discuss this with the installer.
Can I get solid wall insulation as a tenant?
Landlords used to be able to claim cash of up to £1,500 towards energy efficiency improvements using the Landlord's Energy Saving Allowance.
This enabled tenants to cut their heating bills by hundreds of pounds a year. But this was scrapped in April 2015. However, tenants can request consent to install energy efficiency measures themselves. Of course, shelling out thousands for a short or medium-term rental property is unlikely to prove appealing.
However, from April 2018 rented properties must be brought up to an E rating at least on an Energy Performance Certificate (EPC). So you can demand the landlord install measures to improve energy efficiency such as wall insulation if this isn't the case.
*Figure according to the Energy Saving Trust.