I haven't seen persnikety's famous spreadsheet but I built one that I have used to keep track of all my costs. We are in the middle of our build so it is not complete yet but I can share the process I used and I'm sure you can create your own that will work for you.

I started with a table that was in a packet I recieved from a potential lender that listed out all the different detail items they would need a breakdown of. I then separated it out into more detail in areas that I wanted to price separately.

After we had chosen to be our own GC but to hire a builder, etc. we sat down with him to get an idea on the rest of the costs. He gave us a fixed bid for his labor only. Than we got bids from 2 local lumberyards for detail items and then he filled in with some estimates for the remaining items. My columns across are for the builder's estimates, my original estimates, my adjusted estimates (these constantly change), the amount spent to date (updated each time we write a check), estimated amount left (this is a formula subtracting amount spent from adjusted estimate), and amount over/under (this is a formula subtracting my original estimate from my adjusted estimate). I then have separate tabs for all detail items that I price compared - lumberyard bids, plumbing fixtures, doors, windows, cabinets, appliances, etc.

Hope this helps and good luck with your build!