Exterior insulation of house

[Alan Zoff]

In theory, this seems straightforward enough.

You screw plastic spacers to the outside wall (plastic to avoid heat transfer). The spacers also act as supports/retainers for standard insulation boards that are then stacked to form a complete covering, leaving you with a warm but vulnerable exterior. Mesh is then screwed or clipped to the spacers and the mesh is rendered to provide a firm, weather-proof covering. You then paint it as with any rendered finish. Job done. (Obviously, there will be quite a few fiddly bits, notably corners, windows and doors.) It has the advantage that the interior of the property is not disturbed.

It seems ideal for our French house which has lousy insulation - twin-brick walls (the hard red bricks with holes) with no cavity to insulate. The house has panelling and lots of other fiddly stuff on the inside faces of the outer walls so it is not practical to make a false inner wall and insulate from inside. The house roof also has a huge overhang on all sides so would easily "lose" the extra thickness of the external insulation. The walls have a rendered finish at present that needs repainting so now seems a good time to tackle the insulation project and just paint that.

From what I have read, this method tends to be used on large projects by specialist contractors - e.g. new builds, renovation of blocks of flats by councils, etc. But I can't find anyone who has used it on a privately-owned domestic property.

Has anyway on the Forum tried or seen something similar? It seems to me that it ought to be well within the capabilities of a half-decent builder, if not a DIY project. And apart from the spacers, the materials would seem to be pretty standard stuff and therefore widely available.

  

[Albert the InfoGipsy]

You could try asking here:

http://www.greenbuildingforum.co.uk/newforum/

It's UK based but full of people with knowledge about stuff like insulation. Exterior insulation is generally reckoned to be a good idea where it's feasible. My only reservation would be how to get the detailing right around windows & doors to avoid the wind whistling between the insulation & the wall.

[Alan Zoff]

Thanks Albert.

I agree about care needed around windows and doors. I had in mind finishing off all corners by bending the mesh round the ends of the insulation and locking it into beading similar to that used for plastering. If the beading is screwed to the wall before the whole lot is rendered over, that will hopefully produce a good seal all round. Just needs some nifty application of the render to leave a tidy finish and to make sure water runs off correctly.

As I said, it sounds fairly straightforward in theory....

[Gluestick]

A chum of mine has had his new villa in Southern Spain exterior insulated just last year.

Workdone by a German company. He had it done to reflect heat in the Summer etc and preserve heat in the Winter and apparently it is working extremely well.

I gather it's some form of system-building  with the sheets pre-formed. Might be worth doing a web search using German as one of the search fields?

Edit: In fact there is quite a bit here:

http://www.google.co.uk/search?hl=en&q=Exterior+Wall+Insulation+Getrman+System&meta=

 

[Alan Zoff]

Thanks for info. Any idea how much your chum paid or was it "lost" in overall cost of villa?

I have had no luck getting even ball-park estimates from suppliers I have approached. They seem to lose interest rapidly when I say it's for one house off the beaten track in central France.... I imagine it will cost an arm and a leg to get a specialist team of contractors to travel to Auvergne do it, hence my looking at possibility of a DIY, or at least own-spec, option.

[Gluestick]

No idea, I'm afraid, Alan. Can't contect him easily at present, either, as he is currently "Wintering" in Spain.

I don't think it was dreadfully expensive, or he would have been sounding off!

In your own case, I agree: can't be too hard a DIY job. However, might pay you to buy the materials cut to rough size from one of the manufacturers?

Then it's only really the edge finishing that would be demanding.

 

[billyo]

Had a quote from a company last year that worked out a 83 euros a metre, once I picked myelf off the floor I found a decent sized exterior finishing shop and had a word, you can do it yourself for less than half that, but the guy I talked to said that to do the crepi yourself would be a catastrophy as its special, and no company I talked to would do only the crepi part as they didnt want the responsebility of me not sticking the polystyrene or mesh on properly and having the crepi crack at a later date

 

Billyo

[Alan Zoff]

Thanks Billyo.

That's a good point about the render as it no doubt has to be more flexible than the stuff used straight onto a brick wall to allow for movement of the insulation. I will investigate further to make sure I get the proper stuff. I have employed a good local tradesman for plastering work and I am sure I can persuade him to spread it on neatly for me after I have done the hidden part.