You don't see it often, but one of the toughest estimating tasks on a takeoff is accurately calculating rough openings for flankers on a full-length bay window. When the plans call for a walkout bay, you'd better get the flanker sizes right or you'll have two returned windows in the warehouse. This Excel spreadsheet, developed by Mentor, Ohio-based North Coast Wood Products, does the work for you. You can make unlimited copies for use within your company only. Requires MS Excel 97 or higher.