The thickness of shower-door glass varies from 3/16ths of an inch to 3/8ths of an inch. Three-sixteenths is the most common thickness. Shower-door glass may be tempered -- which when broken, will shatter immediately into many tiny, but safe pieces -- or safety glass, which is held together by a center layer of plastic, the same kind of glass used in automobiles. Aluminum door frames are more common and cheaper than brass ones. Whatever type of door you choose, you must recaulk the inside frame where it meets the shower walls once a year, or you might end up with a leaky door and a destroyed bathroom floor. And that's the On The House tip for today.