What to expect during flat roof installation: Property protection and coverage using plywood and tarps. Removal of ALL old roofing material. Repair and replacement of rotten boards/plywood decking underneath the flat roof if needed. Re-nailing and re-securing of roof deck. This will help enhance the look of the roof by providing a flat surface to install the new material to and minimize the chance of premature cracking to roofing material. Inspect roof decking for adequate slope for drainage and advise homeowner if repairs are needed.