Is the issue is from the previous paint prep??? If the deck was peeling when you touched it in the past it is from the previous paint prep. If this is the case simply explain all was done in the past cleaning application to prevent future peeling. More less it doesn't matter how many coats you put on the deck it will still fail of due to the first. The only true way to cure the issue is to strip all the old layers off chemicially or by abrasives. This will be very expensive, with respect to time and chemicials. This will be a learning experence for yourself and others. Treat the customer with all your cham and explain where they stand. Good luck !!
DAFF
