Ah, that ol’ staple of Irish construction – the blockwork cavity wall.
Still very much in use and prevalent and even still being used in certified Passivhaus construction.
Let’s have a little look back in history to see where we’ve come in what is a relatively short time…
Here’s one of the first cavity walls I’d have experience of in the UK with a brick & block cavity wall; zero insulation in cavity. Interesting too for just the 2″ of quilt at ceiling level.
Skip forward to when we were building our house in 2004 and current standard was 100mm cavity with 40mm Aerobord in cavity: u value = 0.49 W/m2K.
We thought we were doing well with 60mm high density insulation within a 100mm cavity; u value = 0.27W/m2K
We did this house in 2007 with additional internal drylining, u value = 0.19 W/m2K (first airtight construction we did btw with pro clima airtightness membrane on battens with airtightness test):
We then did this house in 2008 with a 150mm cavity, u value = 0.20 W/m2K ( pro clima airtightnesss tapes/membranes on masonry openings & ceilings )
Special thanks to Donal Gilroy at gilroyenergy.ie for the airtightness tests (photo is of his blower door assembly)
And this year we’ve been working on the first wider cavity walls at 200mm and beyond (u value = 0.16 W/m2K) which throws up all sorts of problems structurally and finishing in relation to cills, lintels, dpc’s…
As I’ve said before, I still believe we need to move away from the ubiquitous cavity wall; it’s reached it’s limit and we still need to go further. This can only be done with an adequately trained work force and a knowledgeable client base.
For further reading Joseph Little has written some excellent papers on this topic HERE