Next door semi is installing polystyrene external insulation - thoughts, please?

[GlomOfNit]

I live in a semi, built early 20's as council housing, long since sold into private ownership. It's single-skin bricks with stucco render which I have to say we didn't really realise or think about when we bought it 13 years back. The external walls of all the houses along this road get very cold and you do get black mould if you're not really careful with furniture, bleach etc.

Next door's semi is still owned by the council (local housing assoc, anyway) and so are half a dozen others in this row. They are all having what looks like external cladding put on - grey slabs of polystyrene with white vents (I assume that's what they are) in them. Being attached straight onto the external stucco render that all the houses have.

I hadn't heard of this sort of insulation and initially a bit alarmed at health implications (polystyrene is not necessarily a great substance, and I wonder if it'll off-gas, plus there's bits of it floating round outside like snow at the moment!) but more at fire safety. Surely this is fire-safe though? The builder installing it told me it would be covered by some sort of render 'on a mesh' which would help it be fire-safe...

There's going to be a considerable step-down from the front of next door's property to ours when it's done, as the slabs look about 10cm thick, and that's before the render.

We have damp and mould issues (I know council-owned next door does) and I assume this is being done on the council-owned houses to improve fuel efficiency and make their houses healthier to live in. Is this just the way this is done nowdays? Are there any drawbacks? And are there likely to be any effects of having this done next door but not having it done ourselves? (I don't think we can afford this, or not at present. Lucky council tenants, eh?)

Don't flame me! (the polystyrene will go up, for a start ) I just hadn't come across this method.

(I'm a bit pissed off that the local housing association didn't tell other interested parties (eg house owners next door) about this work before it started, not least because it might have been something some of us would have considered getting done ourselves and we might have been able to pay into it somehow and get it done at the same time....?)

Polystyrene is normally blown with CO2 so even it does outgas the risk is effectively zero.

Again the risks are absolutely minimal, it is presumably only two stories so there should be little or no chimney effect.

That should be fire risks but I can't edit - presumably because of the thanks.

We had this done and has made the house much nicer. A shame they didn't see if you wanted "in" - my guess is they are doing it under some kind of grant funded scheme specifically for social housing and probably to a deadline.

However depending on your circumstances it might be possible to get some financial help to do your own. See if your council can link you to an energy advice service - most areas have them.

I wouldn't imagine there would be any health risks. I live in a similar property, also with freezing cold walls and badly insulated, lime plaster, single bricks etc. and would wonder if it would affect the breathability of the walls, making them more prone to damp. But I'm not an expert.

I can't see there are any risks. In the ideal world you'd have been able to be involved to but most HAs are so chronically underfunded they don't even have the admin resource to go about arranging anything else.