See above, more is better, I would go more than they suggest which makes a thick and strong foam that hangs around for minutes.
Agreed - I followed the letter but just wasn't enough. I did the 2" it said, and filled the rest up, so close to a 1-4 ratio, think it needs to be 1-3 at most
You only live around the corner housey, you need to show me the R8 before you bin it!