External Wall Insulation

[Marakith]

Hello!

We're planning a big extension project at the moment, and whilst we've got the "drains up", as it were, we're looking to install a heat pump, solar, and external wall insulation. Our house is a solid brick wall house so it gets really cold in the winter.

We've got a couple of decent quotes in, but they offer 90mm EPS - I know there's potentially an option to go with Kingspan boards instead, but the costs seem significantly higher.

Has anyone done this sort of project before? Do you have any "gotchas" you can share that I should be looking out for?

Many thanks!

 

[Marakith]

I was thinking the same thing, went to EWI store in Chessington and had a loooooooooooooong chat with the guys who were very helpful.
They basically said get the Kingspan as the difference would be incredible, I ended up not getting EWI and went internal for the remaining walls of my house but from what they said definitely get the Kingspan

Thanks!

I've got insulated plasterboard in some rooms but not others. I just had a web-chat with the EWI store guys and the difference between the prices is significant for not a huge difference in performance. EPS 90mm is £8.94 per board for a uvalue of 0.3 and 70mm K5 board is £18.89 for a uvalue of 0.26. So I'll probably go EPS as the improvement over solid walls will still be huge.

 

[Marakith]

Thanks for all the responses. I'm definitely worried about the damp risk - relating to breathability of the boards/ render. If ventilation can mitigate this, then I'm down with that. I've also noticed some houses around my estate showing algae - and wondered if this was a problem with the render. I understood from the folk at EWIstore that their renders were biocidal and this shouldn't happen.