Hi Andrew

I didn't have an engineer who was familiar with ICF and that was a big and expensive mistake. I eventually got the name of an engineer who had worked on ICF and got them to have a chat with our engineer after which our engineer removed 1/3 of the steel reinforcement originally specified. Other works had already been done by then, also we feel massively over-engineered. Ask the ICF company for names.

We didn't use ledger boards. We used block and beam for the first floor and again with hindsight I wouldn't do it. Firstly it needed a crane for a few hours to lift the beams, cost £900, and secondly it provides a thermal bridge from the inside of the house to the midway point of the ICF concrete core. (Not so bad if you put extra insulation on the outside walls.)

For the second floor we used metal joist hangers cast into the ICF - much less of a bridge. The timber joists and Weyroc floor was much simpler and cheaper to install. Good thing we did use Weyroc flooring as it was exposed to the elements most of the winter.

RobinB