Advice/pointers required. I am in the process of knocking up some drawings for an extension onto back of the house. Initial thoughts was to use 73mm bricks so I could tooth into existing brickwork as opposed to 65mm bricks and extension profiles. Using 73mm bricks obviously means that beds of outer brick and inner blocks will not marry up and hence fixing of wall ties would be problamatic. I have seen other extensions built with 73mm bricks so am I missing something here (other than leave the wall ties out)