How does cavity wall insulation work

puddy

by that, I mean how does it get put in, does it mean a redecorate, what if you havent got cavities in your walls? (is that even possible)

i ask this as i am hoping to move, IF i ever manage to sell my property and want to put all the money saving stuff i can into a new house. we like older style houses, either from the 30s or victorian/edwardian houses, i would like to have everything in there, solar panels, loft and cavity wall insulation and a wood boiler stove for central heating and hot water.

but am confused about the wall insulation and the practicalities of it

Cardew

They drill small holes in the wall and inject in foam. This foam sets rather like the white packing material that is used for, say, a TV in box.

Older houses can have single(i.e. non cavity) walls

saver_sam

I had mine done back in the summer. took no more than a couple of hours and i have an end of terrace house so extra wall to be done. Didn't do loft as insulation is very thick and I have lots of 'junk' to clear out first! Mmm must get round to it.

shaven-monkey

The insulation is usually injected from the outside. If there is existing insulation in the cavity then it may have settled or become damp which will reduce its effectiveness and will require it being removed (quite expensive). Insulating material varies depending on tastes, application, date of installation and costs. Not sure if house surveys actually bother identifying what insulate was used when they say "cavity insulated" so caveat emptor.

In a house without cavity walls the rooms can be insulated internally by boxing the internal walls to create an interior cavity and insulation placed into that cavity. This will make the rooms with exterior walls smaller. Another option is to clad the house with insulation but this will require planning permission as it changes the appearance of the house and upsets neighbors who like the asthetic of a money pit.

twinklefish

They drill holes from the outside and inject it in. I did the B&Q insulation thing and when they came to survey they checked me out for cavity walls. Unfortunately I'm in a granite '50s end terrace and dont have the cavities.

Friends of mine have had a fancy new heating system put in that will allow them to add solar panels in the future. Something to do with two heating coils in the hot water tank. I think one that runs from the solar panels but if that's not producing enought heat, traditional heating methods kick in. They also have a wood burning stove but it's just used for heating a roomm, or the whole downstaris if they open doors. This is in a cottage type 1800s end terrace

Years ago I lived in the country and our hot water and heating ran from a back boiler behind a coal fire. (No mains gas) It was terrible and I would never have anything again like that. Put me off open fires for life that did!

mech_2

They drill 2 inch holes in the outside of the wall and fill the cavity from outside by blowing the insulation in through hoses. No redecorating needs to happen indoors. The holes are drilled at the join between bricks and then they make it good with a bit of mortar. It won't really show much. It will just mean some pairs of bricks have corners missing. Or if the walls are rendered you will have spots of mortar which you will need to paint over.

Victorian properties are very unlikely to have cavity walls. If you don't have cavities in the wall (or the cavity is 45mm or less) then they just can't do it. The only ways to insulate the walls then would be either to render it from the outside with exterior insulation, or insulate from inside the house involving replastering and redecorating and you'd lose a couple of inches of room space. Expensive either way. I think most people who don't have cavity walls just put up with uninsulated walls.

Forget about the solar panels, they aren't cost-effective IMO.