Even in homes with flat roofs, there’s likely to be at least some semblance of crawlspace between the roof and the ceiling of the living area beneath it. You may find, after donning a facemask and putting fresh batteries in your flashlight, that your attic is surprisingly spacious. Or you may find nothing but insulation between the ceiling joists, and little room to maneuver. A quick visual inspection is a good first step; an architect can confirm your suspicions later.