Hi. I initially designed the wall to be double 12mm ply/OSB on the exterior totaling 24mm but now found out that timber is a thermal "weak spot" in terms of insulation so figured it would be better to add exterior insulation to the building wedged between the ply/OSB? Here's what I got: So the timber is build on a single skin brick layer. There is already overhang on the inside of about 20mm. Am thinking of splitting those 2 12mm sheets and wedging insulation board in between. Complete with the battens and render cladding this would leave a pretty big overhang. Layers would go like this: Would the bricks and concrete slab and timber framework be able to take the weight of this overhang? That piece of "wood" you see in the top pic would be screwed to the base of the timber framework so the Celotex and plywood can rest on it without putting too much pressure on the edge of the brick. Also the framework studs are 400mm spaced and will be filled with acoustic rock wool which isn't as thermally good, hence the added external PIR boards idea. Yes posted on DIYnot with no replies so giving OCUK a try lol Thanks.