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We’ve seen a house which we quite like but it’s got two of the things I’ve always steered away from, that’s render and external insulation to the oldest part of the solid wall property. I’m probably just a Luddite in thinking external wall insulation is a bad idea but just wanted to throw it at the hive mind for thoughts, pros, cons? Ta.
Interested to hear informed responses, but certainly in Switzerland it's very common place on new builds. Concrete structure, then about 30cm or so of external insulation blocks then the render.
I think it is relatively easy to knock holes in it (our neighbours did it with a garden umbrella on a windy day - oops!), but if the swiss do it I kind of assume it is 'gold standard'.
We have 70's/80's waterproof render on our single skin brick end terrace house and I'm fairly sure that its the main cause of the damp issues that we have. Having said that the house is built from some very soft/porus bricks which might make this a lot worse for us then something that used a better quality base material.
If were going to be be here in the longer term I'd strip it all off and try and work out a way of putting up some external insulation that still allowed the walls to breath properly to keep the damp down. Though I've no idea how I would do this.
We live in an old house (1899) made from porous bricks with single skin render. We have quite a few issues with damp and mould. Our neighbours had external insulation applied and now have no damp or mould issues. Their house also retains heat much better than ours.
It is rather easy to damage though. One of the corners of their house has had to have the topcoat reapplied a few times. Worth noting that it was an utter cowboy that did the work for them and they’ve still seen a relatively positive outcome. The only major downside was that the contractor didn’t use long enough fixings when it came to reattaching the drainpipes and gutters. That was interesting!
Quite a few houses near us have it, looks very good:
[url= https://live.staticflickr.com/7486/16190586106_9fe02c0704_c.jp g" target="_blank">https://live.staticflickr.com/7486/16190586106_9fe02c0704_c.jp g"/> [/img][/url][url= https://flic.kr/p/qEGZbj ]External Insulation[/url] by [url= https://www.flickr.com/photos/brf/ ]Ben Freeman[/url], on Flickr
[url= https://live.staticflickr.com/5470/17676765655_36bf85caa8_c.jp g" target="_blank">https://live.staticflickr.com/5470/17676765655_36bf85caa8_c.jp g"/> [/img][/url][url= https://flic.kr/p/sW33zD ]Brick and Render External Insulation[/url] by [url= https://www.flickr.com/photos/brf/ ]Ben Freeman[/url], on Flickr
We can't have it as our street is a conservation area.
From what I understand, if it's been done right there should be no issues. It's another barrier to the outside elements and the thick solid now internal wall will nicely retain the heat.
There are far more houses around the world that are solid wall, not cavity.
Ditto brick finish.
And Europe is dominated by solid wall and externally insulated properties. Again, far more than the UK has of cavity wall or brick finish.
Done well, it's far superior to brick and cavity.
I'd have it done tomorrow if we were allowed!
9" solid brick walls leak a lot of heat...
we have it as our brickwork facing the prevailing wind was deteriorating badly. we needed to render it and the chaps that quoted suggested insulated render for teh same price as normal render. we went for insulated as its better to have more insulation tan less. Its been decent over the last 6-7 yrs. probably needs a coat of pain and i dont worry about water every time it rains (from the brickwork anyway!)
its definatly helped keep the house warmer over winter.
The cost is the only thing stopping us from doing it.
Depends more on the overall assembly than just ext. insulation is good/bad.
Assuming it's permeable and water resistant (eg.mineral wool), if it's applied outside of a membrane/waterproof layer, then has a small cavity before the cladding, chances are it'll be fine (assuming a cavity, like the pic footflaps posted). Issues can arrise if a vapour resistant type of insulation is used, as it can potentially cause condensation on its inside face, next to the wall.
If it's a face sealed external insulation job (where they stick the sheets to structure, then make it watertight with coatings) I'd be wary. It assumes a perfect water barrier and if water gets in, there will be no cavity or vapour movement to dry it out.
Generally, external insulation is a good thing, as it can be continuous and keeps the mass of the structure within the envelope, which helps store heat and flatten out temperature swings. That said, there's a lot of ways to cock it up too.
If it’s a face sealed external insulation job (where they stick the sheets to structure, then make it watertight with coatings) I’d be wary. It assumes a perfect water barrier and if water gets in, there will be no cavity or vapour movement to dry it out.
Or is breathable, such as Pavatex and Baumit.
If the house is right location it would not put me off at all. Everything else can be changed if needed in due course.
Thanks for replies. It’s a nice house certainly and looks well finished. It’s external cladding insulation so I guess I need to find out what type it is. How does it get finished/sealed up on the gable? It looks to be a pvc edging or the like?
As with anything building related it's all in the details.
Seen & heard of many with issues around the reveals but this is poor workmanship, not an issue with EWI.