I don't know whether this payment request is fair
The builder's figure has arrived, but you cannot see how it relates to the work now standing on site.
What's happening?
A payment request is not just a bill: it is a claim for the value of work completed, materials properly on site and any agreed changes. Unless those parts are separated and checked against the contract and the build itself, the total is difficult to test. Paying it does not make the underlying work easier to measure later.
The practical question is what the work is worth today, rather than whether the request sounds reasonable. A running tracker gives each request a place beside the work, the amount paid so far and the balance still to be earned; an independent check can put a reasoned figure behind the payment decision.
The solution
Put each request beside the work and the running account before money leaves the build.
If you would rather it were done for you, Valuation & Payment Checking is the service that does it.