How much is too much upfront?
I was speaking to an old friend who told me he had been ripped of buy a builder. He paid 90% upfront! Right then I thought where is the incentive for the builder to complete the job? I can’t think of any reason why labour should be paid in advance. My thoughts are that small jobs should be paid after a job is done. Last year I needed a plasterer. One came round and quoted me £1200 but the sticking point was he wanted £800 upfront, needless to say I didn’t use him. Any established builder will have an account with the builder’s merchants so there is no need to pay such a high percentage up front.
I can understand on very big jobs paying money each week as parts are being completed but that is at your discretion. Whatever you do, before you agree have everything in writing as a formal contract. Don’t be tempted for cash in hand work to save money. It could cost you double in the long run. Also do an online search of the builder. See if he has any bad reviews.