Should I get this cavity wall insulation?

[BrokenFoot]

We had a company called Insul8 knock on the door last week offering free cavity wall and loft insulation.

We have already had our loft insulation done but I didn't think we had cavity walls. They checked by drilling holes in the pointing and inserting a camera. They said we do have them.

They have booked in to come on Monday to do the job. When I told my DH about it he was very suspicious. They seemed genuine enough, seemed to know what they were talking about.

The one thing I'm uncertain about is that they said by law they have to install a vent in the living room as we have a wood burning stove. The vent is quite a large (prob 6 or 7 inches diameter) hole and would only have a grill over it on each side so would be very draughty.

Our house is an old Victorian house. After doing a bit of googling it seems this insulation can cause damp/mould in some old houses due to reducing ventilation.

They are going to use a product called polypearl.

Anyone have any opinions on whether we should go ahead with this? We do have a v draughty, cold house and need all the help we can get to warm it up!

I'm very surprised that a Victorian house has cavity walls. But your DH is right to be wary. Old buildings are designed to breathe. I wouldn't do this personally as you could cause damp.

You would need a vent for the wood burner as well, it's a building regulations requirement.

I'd also personally never use a company who cold called, but that's me.

It's almost 100% certain that you don't have cavity walls and these people sound like scammers. In what way is the treatment free? Please unbook them. The draughts are likely to be coming through windows/doors/chimneys rather than through walls so, even if they were able to insulate them, it would make very little difference.

lala there are govt grants available for cavity wall and loft insulation. It is free. British Gas did ours about three years ago and it has made a difference.

You can often tell whether there is a cavity by the thickness of the walls around door frames. PigletJohn knows these things.

I do think in a Victorian property cavity walls are unlikely and that could be where the scam is - could the house be Edwardian instead?

A few Victorian houses have cavity walls or something comparable. It i rare. Measure the thickness of your walls at a door or window opening. It will usually be about 9" plus plaster, or 13" plus plaster. A large old house may be more, especially if it is more than 2 stories. Victorian lime plaster may be more than an inch thick.

Generally, avoid doorknocking canvassers. They probably get paid per appointment made, the doorstepper may have no idea of the suitability of your home.

Try BG. Even if you are not a customer they often provide free or subsidised energy-saving measures as part of their legal obligation. They are obliged to put aside about 12% of their gas sales. They are obliged to rectify any work they do which turns out to be defective or unsuitable, and they are now very reluctant to install where the house is unsuitable.

I have never heard of the doorstepping company you mention. Your local council or electricity supplier may also have a scheme.

Personally I would cancel the appointment, because the company might register you as their customer to prevent anyone else approaching you.

p.s.

Polypearl sounds like they are going to pour expanded polystyrene beads into your walls. These have a bad reputation because they can settle into gaps under windowsills, and pour out of any holes during building work or e.g. replacing windows. Some modern versions include a glue that make them set into a solid block, which should be better.

If the installation is scheduled for Monday you have little time to cancel. I doubt you have cancellation rights if the salesman called in response to an agreed appointment.

As far as I know you only need a vent fora fire more than 5 kw

I was going to say what Ruhr said - pretty sure you don't need a vent unless your woodburner is above 5kW -especially in an older less air tight property.
I wouldn't use a company like this either - cancel them. There are mixed reports on cavity wall insulation - shouldn't be done to exposed walls etc can cause damp - cavities were used for a reason - to stop water coming through walls!
It should also be guaranteed for 25? or maybe 30yrs....and if you find you need some comeback- you don't want to find they have 'gone bust' (and probably operating under a new name! Problem I had with my badly installed so warped double glazing - done by a previous owner it was still well within the 10 yr guarantee - sadly the installation company had 'disappeared'...guarantee was useless)

You can get it done free by big companies like British gas - and I would use one of those - you should be able to get them back if there are any problems...
Remember - if it does cause problems and especially if it is the set stuff think about how difficult it will be get it out again ... (at least there is some chance of them being able to suck the fibreglass stuff/loose beads out again from smallish holes)....

Thanks all, think you've convinced me. It was only Thursday I think that they called around so even though it would be short notice to cancel I will try. I have a mobile number for them.
The wood burner is 7kw so the vent would be needed.
They said it comes with a guarantee by an external regulator who inspects their work but I agree you never know how secure that is.

I shouldn't say this ...but I have 7Kw and no vent...it was a last minute change of plan (was having a smaller one but liked the design of the larger one...)

It is in a large room in an older house, I have a CO monitor - whilst not strictly in line with building regs I'm not worried about it...

No I wouldn't be worried about it either as there are plenty of draughts in our house! But they said they're heavily inspected so they would have to install it to cover their back which I understand. Pretty sure I'm going to cancel anyway, and carry on embracing several layers of clothing!!

Tips for reducing draughts in older houses - check your floor boards and use masking tape to seal the joins if there are any gaps for draughts. Draught excluder on windows and doors. Have really thick curtains up at the windows and consider a curtain behind any doors to the house.

Check when you had the loft insulation done as the recommendations for depth changed and you may be able to have more added for free.

Also remember that reducing the flow of air may cause damp so it is a balancing act between reducing draughts enough but not too much

Avoid. Victorian won’t likely have cavities and yes, insulation can be a problem. Look at www.cavitech-uk.com/blog/how-weather-affects-our-homes-and-cavity-wall-insulation/ for more info.