I have a question regarding joist sizing and spacing. I see there is already and old thread on this topic but it doesn't seem to work when I click on it. I'm going to build the shed out of Jack Sobon and Roger Schroeder's book 'Timber Frame Construction' and use it as a cabin. I want to increase the width of the cabin to 14'. The book recommends that you increase the size of the joists to do this but doesn't specify the size needed. Am I looking at 4"x8" joists? I'm assuming that spacing the 4"x6"'s at 16" o.c. won't solve the problem as it's joist sag that is the issue. Thanks.