but if they want a itemized bill then they will pay for every screw and bolt that I use.
As contractors, we know we always carry forward items from one job to another, so a job prior paid for the handful of screws you are using in the present job. And the present job is paying for the leftover piece of window flashing that will be used on the next job. And that job...
But an interesting thought:
For such itemization of minutiae as the customer desires, where exactly does consumables come in, like sanding paper, saw blades, safety glasses, ear plugs, screwgun bits, buckets, compressor oil, etc. ?
Or are these items something we as contractors are just supposed to eat?
I've done some time/material jobs where the cust wanted to purchase the items themselves--for a variety of reasons. So sometimes they get cheap garbage, and/or not enough, or the exact amount. All this results in my time lost which translates to them into higher labor costs/charges
or the reduction in our price as we then have to work fewer hours per (that) day (week). Our fixed costs are the same, fuel is the same going/coming, etc. but if we only work 6 hours instead of 8, we got paid 20% less for that day--yet our fixed costs were the same for that day.
And if the job takes longer, not only are we making less money and even losing money, we are missing out on actually making what money we should be making by doing other jobs for our 'standard rate'. This is the "opportunity cost" we (sometimes) pay by working for people/businesses that short/fight/haggle/cheapskate us.