Has anyone had cavity wall insulation on a Victorian house?

[onlyconnect]

We're due to have it free through a government grant but having read stories about damp and condensation I'm starting to worry about it. Ours is a late Victorian detached house and we've been told it's suitable.
Has anyone had cavity wall insulation on a similar property who can tell me how it went please?

Told by who, the people being paid to install it ?

Surely your Victorian house will have solid stone walls and no cavity,,,

Second the "told by who" - in theory we have cavity walls, but the gap is very small and the bricks are way too fragile. I know this because we've knocked some of them down. The guy who tried to sell us cavity wall insulation before that was sure it would be ok. It would not have been.

Most Victorian properties aren't suitable because they're solid wall. Occasionally you'll get an anomaly but rarely. Edwardian will occasionally have cavity and anything from 1930 onwards.

It needs to have a 50mm cavity for it to be suitable. Some firms will say 40mm is fine. I would disagree. Did the surveyor leave you any paperwork?

(Ex cavity wall surveyor)

I'll look for paperwork but I don't think he left anything with any actual info on it. We're not paying but I take it that someone is, and yes it's the people doing it who have said it's suitable.
Thank you for your replies. I'm going to look into it further.

i wasn't aware victorian houses had cavity walls...!!...from 1960's yes.

Our place is 1920s. It has had it done, but it wasn't a great idea according to our surveyor; it also made a hell of a mess w.r.t. the brickwork, which has very narrow pointing so it knackered the corners of the bricks. And from access we got doing other work, a lot of it has just disappeared- touch it and it goes to nothing, like dry white froth which turns to dust at the slightest touch.
We have thought of having it done to the upper extension part (1970s) but aren't too sure about even that- we'd have to have it done from inside just for starters, I'm whatsitted if I'll let them drill through roughcast, given the horlicks the previous lot made of the lower bare brick parts.
It was great on our old 1960s house. But here, on the 1920s bits, I don't think so.

@earsup

i wasn't aware victorian houses had cavity walls...!!...from 1960's yes.

Ours is 1920s and has cavity walls- just rather narrower than modern cavities.

I wouldn't do it.
If there is a cavity and I very much doubt there is it is there for a reason. If you fill it with insulation you can create a problems including damp penetration.
Also the cavity needs to be wide enough, and Victorian properties were not constructed like that.

I remember seeing one (rather large and impressive) late Victorian house during demolition, it had a cavity wall made with a 9" and a 4" leaf. Very unusual AFAIK.

More common in smaller, economical houses is rat-trap bond, which used bricks on edge and has a small, incomplete, irregular cavity which I don't believe is suitable for CWI. The header bricks bridge the cavity so there is not a damp-resisting isolation.

Perhaps you have an early cavity wall. Can you measure the thickness, at a door or window opening?

it would be wise to inspect the inside of the cavity with an endoscope as there may be builders rubble in it. I don't know what sort of wall ties might have been used. Perhaps wrought iron.

The major companies (especially when working on contract via councils and energy companies on subsidised schemes) are very cautious, because they can be compelled to remove the CWI if they install it in an unsuitable building, at their own expense.

@PigletJohn

I remember seeing one (rather large and impressive) late Victorian house during demolition, it had a cavity wall made with a 9" and a 4" leaf. Very unusual AFAIK.

More common in smaller, economical houses is rat-trap bond, which used bricks on edge and has a small, incomplete, irregular cavity which I don't believe is suitable for CWI. The header bricks bridge the cavity so there is not a damp-resisting isolation.

Perhaps you have an early cavity wall. Can you measure the thickness, at a door or window opening?

it would be wise to inspect the inside of the cavity with an endoscope as there may be builders rubble in it. I don't know what sort of wall ties might have been used. Perhaps wrought iron.

The major companies (especially when working on contract via councils and energy companies on subsidised schemes) are very cautious, because they can be compelled to remove the CWI if they install it in an unsuitable building, at their own expense.

Our 1920s house has thundering great wall ties. I liberated one from a bit of wall that had been taken out (which I replaced using modern ties). The one I liberated I have been using as a tool for all sorts of jobs. It's iron, very chunky, was slightly rusted, and you could still knock 6" nails in with it, no trouble. I used it for levering bricks into the right position in my mortar when putting new bricks in the brickwork when filing holes made by removing pipes, etc.. It's fast becoming one of my favourite tools. I can also confirm there was bricklayer's mortar waste in the cavity (from a 1970s upwards extension) and a nice pile of original black ash mortar dust at the bottom of the cavities, which we cleared out to stop damp creeping up the cavity. It's amazing what turns up in cavities. And for my money, in most areas of wall in older houses the best thing to have in the cavities is what they're designed for- i.e., nothing.

Thank you everyone. I've cancelled it.

@onlyconnect

Thank you everyone. I've cancelled it.

Most of this house is lime plaster, but the kitchen we have had to have drywalled. We did it with proper battening, not dot-and-dab, so that added another air gap for ventilation, and then used an insulated plasterboard on top. It feels a lot warmer even now when it's not cold out, and the cavity remains intact and empty except where we got access to a section that was bone dry and fitted cavity batt. We'll do the same when we remove the dot-and-dab mess on the diner part of the same room. You do lose a good few cm on the room if you do it the way we did, but in this case, it was worth it. And we only did it on the outer walls, of course.

@onlyconnect

Thank you everyone. I've cancelled it.

I think you have made a good decision. My friend had CWI in her Victorian terrace and it has caused terrible damp problems where there are bridges between the walls.

You've made a wise decision. I used to work in the business and it is very unusual to have cavities big enough to insulate in Victorian houses. If you look at the way the bricks have been laid,it would tell you. All long ways= should be a cavity wall,long ways and headers= no cavity wall. I think you've saved yourself a lot of effort and trouble by cancelling,and I find it very susy that any reputable company would consider trying to insulate a house built without proper cavities.

We’ve lived in our 1920 house for ten years, previous owner had it cavity wall filled. Like others have said, it has destroyed the corners of bricks. No dampnissues to date though.
She also had it underpinned and never told us

Our house was built in 1904 and the previous owner put cavity wall insulation in. It’s been a nightmare and has cause all sorts of water ingress issues where anything has touched the outside in the rain. When we do our upcoming big renovation most of it will be coming out.
I think houses like this need to breathe, and luckily I’m a stick a jumper on and turn the heating off sort!

My house was completed in 1899 (end of Victorian era) and it has quite sizable cavity walls.
In these rare cases it's better to see if there's access via the loft and poke fibreglass insulation down it. Rip the fibreglass apart first so it's thin and breathable.

One problem with having nothing in the cavity on old houses is that the air inside the cavity is the same temperature as outside, when cold it makes the inside wall cold. Warm air inside/cold wall inside means it’s more prone to condensation.

We had a 1903 semi with cavity walls. Got the free cavity wall insulation. It was fine, for several years, until the pointing on the brickwork started failing (just age). Needed redoing but we never got round to it. Heavy rainy winter and the damp bridged the cavity and we had constant damp on a wall in the hall.

Be very careful.

Hi, I hope you don't mind me jumping on your post. I'm about to buy a victorian end terrace house with an epc certicate of F. I'm looking for ways to improve it and wondered if you figured out a way to get cavity wall insulation?

We have a 1930s semi. It has cavity walls, but with a small cavity only (maybe 40-50mm?). In theory it has had cavity wall insulation fitted, but we removed a five meter section of wall for an extension and found precious little.

On the up side, we haven't noticed any issues with damp, but that's probably because there's almost no actual insulation anyway!!

Air is a great insulator, I would not have cavity wall insulation on any house, as soon as you create a single skin wall, you also risk having the dew point (condensation) within the wall which leads to damp and mould. My neighbour has spent thousands having his cavity wall insulated removed because of the damp problem. Also air bricks are there for a reason, to conduct the damp away , keep them open .

An end of terrace, with a blank or mostly blank sidewall, is one of the few cases where external wall insulation is worth considering .

If the wall is rendered, painted or has unsightly cheap brickwork you will not spoil the look of the house.

Are you sure it has a cavity?