I am worrying too much about a project. I designed a light framed construction (wood) building and the 2nd floor contained gypcrete floors over the top of 3/4" decking. I understand that all diaphragms are semi-rigid even if plywood or metal roof deck is used, but one could argue that gypcrete makes it absolutely rigid. I've already submitted the job with a flexible diaphragm analysis, but thought I'd get a discussion going.