Can You Insulate Narrow Cavity Walls?

Question: Can You Insulate Narrow Cavity Walls?

For some years now, companies such as ours have been offering free retro-fitting of cavity wall insulation as part of a government effort to reduce the country’s carbon emissions. Normally this is done by drilling a few small holes into the walls of a house and blowing rockwool insulation into the cavity. This can be done if the cavity is wider than 50mm. But what if your walls have narrow cavities? Is there an alternative? What is the minimum depth that you can have cavity wall insulation?

‘Hard to treat’ cavity wall insulation

Cavity walls that are too narrow to insulate are classed as ‘hard to treat’. Conventional rockwool insulation can’t be used in narrow cavities as it has a tendency to get caught on wall ties and lose bits of mortar, and it’s difficult to blow it into small awkward spaces. In the past, the best thing to do with hard to treat walls was to install external wall insulation (EWI) — which is available for free to certain people.

Despite the fact that it is free to the homeowner or tenant, EWI is still expensive for the people who fund it. Keen to find a cheaper alternative, insulation companies have developed a new type of insulation material that can be used in narrow cavity walls.

Go Greena are now pleased to be able to offer hard to treat cavity wall insulation. Hard to treat insulation uses a special type of micro-bead. The beads are injected into the walls and can flow freely into the smallest of spaces. This means that homes that previously couldn’t have cavity wall insulation now can. The best part — as long as you meet the criteria, you can have it done for free (more info here).

How hard to treat insulation works

What is the minimum depth for cavity wall insulation?

A cavity wall is classed as ‘narrow’ if the gap is between 40–49mm. Standard cavity walls are 50mm or wider, and can be treated with conventional rockwool insulation. Both types of cavity wall insulation are available for free to certain households.

How do I know if I have narrow cavity walls?

One of our trained energy surveyors can drill a small hole in your wall and inspect your cavities. They can determine the depth of the cavity and whether or not it is already insulated. This is a free service, and there is no-obligation. You can arrange a free energy survey here.

More Information