Mud and Screws Are Eating Your Overhead
Joint compound, tape, screws, corner bead, blades, caulk, and plastic come off a revolving supply house account on one monthly statement with no job written on any line.
Most trades buy material by the job, where one delivery and one PO match one number in job cost. Interiors runs a daily drip of consumables plus a stocking operation that moves tons of board vertically before production even starts, and neither one looks like a job purchase when the paperwork comes in. The stocking hours in particular disappear into field wages with no installed quantity to measure them against.
The size of it
Two to four percent of contract value drifts out of job cost and into overhead. Every job reads slightly better than the truth while overhead reads bloated, so you cut the wrong line and then bid the next job off unit costs missing their true consumable and stocking load.
The foreman buys off the truck at the local supplier all week, picking up compound, tape, screws, corner bead, blades, sanding media, caulk, masking, plastic sheeting, and drop cloths. One statement comes in at month end with no job reference on the line items, so the whole thing posts to overhead. Separately, board gets boom-trucked into the building and rough-carried to the floors before a single sheet is hung, which is real labor and real rental spent ahead of any billable installed quantity. Both costs are incurred before the first pay application on that area.
Three moves, in order
Step 05: Software and bookkeeping alignment
Live job costs inside thirty seconds, with the bookkeeping cadence that keeps them true.
What else costs interiors contractors money
The same mechanism in other trades
What interiors owners ask
Supply house account charges never get assigned to a job?
Joint compound, tape, screws, corner bead, blades, caulk, and plastic come off a revolving supply house account on one monthly statement with no job written on any line.
What does it cost?
Two to four percent of contract value drifts out of job cost and into overhead. Every job reads slightly better than the truth while overhead reads bloated, so you cut the wrong line and then bid the next job off unit costs missing their true consumable and stocking load.
What do I do first?
Make the supply house require a job number at the counter and on the truck, and have them print it on every line of the monthly statement.
What are interiors contractors supposed to be making?
Interiors runs 19% gross margin, 13% overhead and 6% net profit before taxes at $1M–$5M. The all-trade average is 7%, so this trade sits 1 points below it. The CFOS target is 10%.
Which part of the system fixes it?
The step is number 05, software and bookkeeping alignment. Live job costs inside thirty seconds, with the bookkeeping cadence that keeps them true. It comes from chapter 5 of CONTROL: The Construction Financial Operating System.
Josh Luebker ran commercial construction projects before he ran the numbers behind them, on data centres, military bases, hospitals, and high-rises. He wrote CONTROL: The Construction Financial Operating System, which is an eight-step framework for commercial subcontractors, and it publishes on October 1, 2026. He is a master electrician who moved into the office and kept the field vocabulary.
Sulphur Prairie Operations LLC maintains the benchmark reference behind these figures. Every edition is reconciled against the newest CFMA survey release before it publishes here. Where a figure changes between editions, the older edition keeps its year in the title so a citation to it stays correct.