Cavity wall insulation – jargon and FAQ

Cavity wall insulation is one of those things that seems daunting. Engineers, fitters and inspectors all seem to speak the language and have all of the knowledge, and it can be difficult to get your head around exactly what they are talking about. So we’re looking at some of the jargon and some of the frequently asked questions about what goes on when you get your cavity walls insulated.

What is a cavity wall, do I have one?

A cavity wall is a wall that has a gap between two layers of brick. You may remember from school that heat travels better through solids because the particles are closer together, so the air in the cavity helps to stop the heat loss compared to walls that are solid. Most homes built after 1920 have cavity walls, and those built before 1982 were built without insulation in them (and some built after then due to some companies not updating their regulations). The Department of Energy and Climate Change (DECC) say that if your walls are at least 250mm (10 inches) thick, then it is likely that it is a cavity wall.

Foam, wool, bead?

Foam, wool and bead are the different types of materials that cavity walls can be insulated with. We already did a post explaining the differences and the different pros and cons of each material. You can find that here.

What is extraction?

It is exactly what it sounds like – we use an industrial vacuum cleaner to suck out all of that old insulation. We may do it if you have an unsuitable material for your property, if your insulation wasn’t installed properly, or if it has developed a defect such as it is now full of water or damp. Badly insulated cavity walls are often worse than having no insulation at all, so an extraction is the best way forward.

What is a drill pattern?

Unfortunately, we can’t just drill one hole in your wall and go from there, you’d end up with all sorts of problems from uneven distribution, and so multiple holes are required. But it’s not just drilling willy-nilly, each different material has a recommended drilling pattern from the designer of the material – to ensure the best distribution; protecting you against cold spots and possible damp problems from uneven insulation.

What’s my guarantee?

Each cavity wall insulation comes with an insurance backed guarantee – which means that we install your insulation and then it insured against defects for a minimum of 25 years, as long as you don’t deliberately damage it. This guarantee will cover extraction and refitting if it was installed improperly and causes problems. Refer to your guarantee paperwork in the first instance.

What are the different kinds of funding? CSCO, Green Deal?

Yes, CSCO and Green Deal can be used towards the cost of having your cavity walls insulated. CSCO stands for Carbon Saving Community Obligation, which means that the big six energy companies have been placed under an obligation to help reduce heat loss in certain low income communities. Green Deal allows you to borrow the future energy savings that you’ll make by having improvements installed to pay for the initial installation. Click here to learn more about CSCO funding, and here to learn more about Green Deal funding.

Yeah, but I bet it’ll take forever

A cavity wall insulation job looks like it will take forever. There are all sorts of machines for the installation, drills for the walls, cement to cover the holes afterwards, and it does seem like you wouldn’t have the time for it to be done. But you’d be surprised.

Extraction tends to take a full day for a standard sized, 3 bedroom property, because it is a complicated process. But even that probably isn’t as long as you would think it would take. Installation times for insulation depend on the material; but should take a few hours at most as long as you don’t have an unusually large house. More specific figures are found in our spotlight on the different materials.