Do I have to pay the final bill while snags are outstanding?

The end of a build is a trade the contract already anticipates: the builder wants the account settled, you want the work finished, and the honest position sits in the middle. Paying everything with a promise attached converts your last leverage into goodwill; refusing everything over a modest list is the other unfairness, and it sours a settlement that was close. The commercial answer is to price the gap: put a fair cost against every unfinished or defective item, hold that - and only that - from the account, say so in writing with the priced list attached, and release line by line as fixes are evidenced. That position is difficult to argue with precisely because it is fair. Where settlement wording needs legal force - full and final, disputed sums - that is a solicitor's ground, and the close-out says exactly when to take it there.