I have an old deck that I am planning on refinishing. The ledger, post and joists are all in good shape but the floor and railing are all going to be replaced. One issue I have is that the existing ledger does not have any metal flashing on it. How can install flashing without replacing the whole ledger. The house is clap siding and there is a sliding patio door where the flashing would come in contact with. Any advice would be appreciated.