I understand that joists should not be built into the inner aircrete skin, and that where denser material is used as a padstone for joist hangers, extra insulation is required (I guess a bit of celotex instead of the glass fibre batts). But, what is the usual padstone for the joist hangers ? A single clay brick ? Also, anyone know the minimum height you can cut an aircrete block (e.g. to align joist hangers vertically) and still maintain stuctural integrity of the block. Thanks, Simon.