Twas wondering if anyone can help. I've been looking at insulation batts for walls. Researching on the net, R2 cost about $3.80/ M² and R2.5 is double at about $7.60 /M². They are the same depth at 90mm, one is denser I assume. I'm in Sydney, near the coast but not on it and I was wondering is it worth the the extra cost, which is not going to break the bank but I can think of other things that I would like to spend it on if it is only a negligible difference? It will be in a brick veneer, wrapped with double glazed windows. For the all external walls it is about $900 or $1800 for the R2.5. I was thinking that the 2.5 might be a bit stiffer and maybe they wouldn't slump as easily over time in between the studs giving better long term results.
Thanks for any input.
Bruce