Curious! EXTERNAL insulation on a victorian semi...

[Aethelfleda]

I was remided of this by the "internal insulation" thread that's just popped up...

There's a house localy that we wall past on the school run. Nice Victorian semi- well, it probably was, until someone grew very old and frail there, let it completely go, and by the time they died/moved into a home (don't know which) it had been neglected for I'm guessing about 30 years. We're talking lots of external brick crumbling, rotten window sills and lintels, garden a mess of weeds/broken up path. Leaky looking gutters etc.
So someone has bought it, taken down all ceilings and replastered, put in (twitch) halogen lights, is building a porch on the front, etc.

The weird bit I am curious about: rather than insulating the walls on the inside (I think it's too old for cavity walls) they have clad the entire outside with polystyrene blocks, and covered it over with what looks like render, and painted it. That's it! So it's now brick/polystyrene/render!
Is this usual practice? How the heck does the building "breathe"? More to the point, when they market it to an unsuspecting buyer, how would the buyer know what's under that render (ie lots of crumbly looking bricks?)

It does look very smart! But is it usual to do that sort of thing, has anyone heard of it before?
(I have no intention of buying it, we already have a house, just like to know stuff and this seems so weird!...)

It is a perfectly respectable method, popular in other parts of Europe. I would have thought you need planning permission, as it drastically changes the appearance of a house. There is usually a fibre cement board and/or plastic or stainless mesh bolted to the wall before rendering.

The ground floor needs something more substantial than the ordinary boards and render as if will crack when people or bicycles bump into it.

A Victorian semi will look horrible.

Thanks pigletjohn, it just looked so weird when it was all going on, and seemed to me to be hiding a multitide of sins underneath!.... It does look very much like a professional refurber rather than a DIYer job, there's not lights on in the evenings if we go past so I don't think the owners are living there, I was just really surprised that polystyrene with a bit of render over the top would be a long enough lasting "outer coat" for a building. I suppose non-UK buildings are more likely to be non-standard brick construction, maybe that's why it's seen more in Europe. It's not really to my taste but hey, I live in a newish build so have no basis upon which to get sniffy!

Anyone know if houses clad in polystyrene get damp problems?

The walls will be warmer, so less prone to surface or interstital condensation. There is very little ventilation through solid walls, and the evaporation from the outer surface is just rain that made it wet earlier, which the layers will prevent.

The residents will still have to ventilate away the water vapour from breathing, cooking and showering, and if they drape wet washing around, their home will be very humid.

If the house does get moist, it is pretty certain to be because they have cut ventilation by removing draughty old doors and windows, and fitting hideous plastic ones that they keep firmly shut.

that's what a relative did. basically they created a cavity by putting rods on the wall and glueing polystyrene blocks onto those.
cavity means that the old wall can breathe.
house has a lovely feel to it, no damp issues. very expensive and messy though. different country, so they had to put on insulation or they wouldn't be allowed to sell or rent out.