Hold on to your money until it has been completely earned by the person you have hired to do a job. Even under critical emergency conditions, complete, good quality repairs must be done or damage and deterioration will appear at a future date. Strengthen the patches and wait patiently until you can be sure of a good job. Then, start with a clear, complete contract.
Contracts are the best way to handle matters. A contract is a promise or set of promises for which the law gives a remedy in case of breach, or the law in some way recognizes their performance as a duty.
Signatures of parties making the agreement and the date are essential. If money or other considerations change hands before the entire contract is completed, signed receipts should also change hands.