Alternative to Thermalite building blocks?
We are building a single storey extension and our plasterer is insisting that we don’t use thermalites on the outside as the render will crack. He’s a good plasterer with lots of experience and I trust what he says. Concrete blocks will do, but they have low thermal properties. Is there an alternative that will give better thermal values but won’t draw all the moisture out of the render or crack it due to the expanding properties of the blocks?
I didn't find the right solution from the Internet.