What are my rights in delaying payment to builder?

[TrudyTrudy]

I have been having quite a bit of work done to my house by a building firm (replacement bathrooms,garage conversion,electrical work etc) I have signed a contract which states that the job would be completed in 18 days and that payment would be required on the completion of the full job. Unfortunately the job has overrun time wise and the en-suite will not be finished on time. The builder has said that he will return next week to complete the en-suite but he wants to be paid for all completed work now. I know that I am within my rights to withold payment until the full job is complete but I also wish to have time to check that the work has been done satisfactorly ie no leaks, loose fittings etc., as there have been many already! As I am not due to move into the property for another month or so I feel that I may not be able to check this out properly before it has been 'lived in'.
Could anyone tell me whether this extra 'check over time' would be considered reasonable by most builders?

[buildersmate]

If you have a contract that states payment will made on the completion of the works then, fine, withhold all payment until completion of the works is made. You will know that a high proportion of tradespeople are renown for not coming back in a timely manner once they have the majority of the payment, so your strategy is a good one.
However, once the work is complete, it is incumbent on you to check it there-and-then (i.e. within a couple of days) and pay up, unless you included a retention clause to cover this, which it seems you didn't. The second part of what you are asking is unreasonable and not allowed for in your contract. Tradespeople have cashflow issues, too.

[AlBags]

I think it is quite reasonable to pay by cheque when job is finished, so long as you look around and check work first. Get someone to check it properly, and if there are serious issues, contact him immediately and request a response. If no response, you could cancel the cheque, although he may pay to quiuck-clear it. Beware.
I don't blame you for being careful. Once bitten, twice shy!

[dothawkes31]

Don;t part with any payment until the work is complete, everything is legal and works properly, and then make sure you get a duplicated reciept and a copy of any snagging list.

[buildersmate]

What snagging list?
If you have a contract that states payment will be made on the completion of the works then, fine, withhold payment until completion of the works is made. So there won't be a snagging list of outstanding work.
It must be groundhog day.