- I don't think it's super common in the US - it's a high-tech product that quickly loses its legolike value if quality controls get sloppy (you have to spend hours sanding down each row or switch to mortar) - it's just walls, you still need a system for building foundations, floors, ceilings and roofs.
AAC floor and roof panels do exist.
My impression is that ICF is a lot more common in my area than AAC, though it's still not super common compared to, say, stick frame construction. I'd guess that's probably because with AAC you'd need to add additional insulation, whereas with ICF you wouldn't -- but maybe there are other reasons.
Northwest AAC claims even higher values: "[f]or example, the R-value of a typical <...> 12-inch wall is R-29", so either I'm converting the wrong values or the measurement standards are very different across the countries. Xella (Hebel) claims their blocks are warmer than standard blocks, but 50% more sounds like too much.
