Cavity wall insulation makes your home easier to heat by preventing heat loss through the walls, cutting your costs and environmental impact. However not every home will need to have cavity wall insulation, either because it has already been installed or because your home is built using a different wall construction.The frequently asked questions below provide information on cavity wall insulation and what Lewisham Homes is doing to provide this where needed.
How can I tell if I’ve got cavity or solid walls?
Properties were only built using a cavity wall method from the 1930’s, so if you live in an older property then you will have solid walls and therefore cavity wall insulation will not be suitable for your home.
If you are unsure how old your home is, you can also tell by looking at the walls whether they are cavity or solid walls.
Cavity walls are about 10 1/2" to 12' (270mm - 300mm) thick overall and you can measure this at a door opening.In addition, all the bricks visible on the outside of the wall are laid long ways, except at corners and openings, so you won’t be able to see the short end of the brick on the wall.
In solid walls on the other hand, the bricks are placed lengthways and head-on, so you can see both the long and short sides of the bricks.The walls are usually a little over 9" (225mm) thick, although in larger properties the walls can be 13 1/2" (330mm) thick.
How are cavity walls insulated?
Small holes of about 22mm-25mm in diameter are drilled in a pre-determined pattern.Cavity barriers are then installed to prevent the fill entering the cavities of adjacent properties.Air vents that cross the cavity are then protected.The fill material is then injected into the wall cavity.Quality checks are conducted on the fill material to ensure the cavity has been properly filled.
How are the holes filled?
The holes used to inject the insulation are filled with matching mortar and are barely noticeable, if at all.
I live in a flat that is part of a larger building – can I get my flat insulated?
Cavity wall insulation must be installed in the whole building; it’s not possible to just insulate a small part of it.This is why Lewisham Homes have surveyed all of the blocks of flats to see whether they do need insulating or not.
I think my home does need cavity wall insulation, what should I do next?
Lewisham Homes is putting together a programme of works to install cavity wall insulation.This webpage will be updated with information on the programme of homes that are scheduled to have cavity wall insulation done, so you can check back to get an update.
