I think if we asked 5 different contractors, we might come up with 5 different answers. There is not a hard and fast standard, but I am compelled to share the fixture allowance policy that was a success for my company. Over time, I felt that helping the client describe what the fixture looked like early on was a great help.
If we were doing a lav faucet, we’d specify the following: Widespread lav faucet, polished nickel, 12” o.c. With a cast brass housing, pop up and overflow to match, and white porcelain cross handles. [Allow $400 our cost]
We put our material markup on the 400 and we were free to show them our invoice. Overages and underages were calculated without markups to avoid confusion. Overhead and profit numbers were never mentioned. Most of the time, we could give them back a refund. That, they really liked!***[C/T,NARI]