Hi there,
Usually when you have a large amount of construction work done you would create a JCT contract with your contractor or builder, which would include the agreed snagging timescale, usually 6 or 12 months, depending on the nature of the works carried out. Another acceptable clause in the contract would be to hold back a retention (5% of the overall cost of the job), half of which to be paid on the primary defects snag at the end of the project and the other half to be released after the 6 or 12 month snag. This leaves a budget to pay someone else to do the snag If the contractor does not come back to complete.
Hope this helps