My code (that is right MY CODE!... not yours ) states "bay windows, box windows, and chimneys" may encroach into the required setback no more than 24 inches. Working with a builder on a plan and he has a bathroom pop out that is 24 inches by 12 feet. I had to reject the site plan as it is not a bay or box window. I have always used the test that if there is floor space without foundation support, it has to meet the setback. I know we can get into a nice discussion of what really constitutes a bay window or box window and we can even throw in bow windows. While we are at it, can we try to define what constitutes a porch? Patio? Deck?...another time. The builder's argument, which I feel has merit, is what does it matter what is on the inside of the wall? You have a projection into the setback. Who cares if it is a window or cantilevered floor space? I've drafted a code to allow any projection up to 24 inches by 10 feet to be permitted, no more than one per elevation, and no more than two per dwelling. What is your SOP?