A service call is simple. You show up, fix the problem, collect payment. A whole-house repipe is a different animal. It can run several days, require a lot of material purchased upfront, tie up multiple techs, and produce a large invoice at the very end. If you wait until completion to bill, you have effectively loaned your customer the entire cost of the job.
Picture a $12,000 repipe. You buy $3,500 in materials the week before the job. Two techs work for four days, which costs you payroll and burden for roughly 64 hours. Add truck costs, permits, and drywall coordination. By the time the job is done, you may have $7,000 or more out the door and nothing in. If the customer pays net 15 or takes a few weeks, you are carrying that cost on your own cash. A few of those at once can put a real dent in a small shop. These figures are examples, but the pattern is common.
The fix is to bill in stages that match the work. A common structure is a deposit when the contract is signed, a second payment when materials are delivered or rough-in is complete, and the balance upon final completion and inspection. The exact percentages vary. Many contractors use something along the lines of a third at signing, a third at rough-in, and the remainder at finish, but you should choose what fits your job size and customer base.
Write the milestones into the contract or proposal, so the customer knows from day one when payments are due and what triggers them. Vague terms invite delayed payments. Clear milestones tied to visible progress rarely cause arguments.
Here is where job costing earns its keep. If you only compare the final total to the estimate, you learn whether the job made money but not why. Break the job into phases, such as demo and access, rough-in, connections and testing, and cleanup or restoration coordination. Record the hours and materials for each phase.
After a few jobs you will start seeing patterns. Maybe access and demo consistently run over because older homes surprise you. Maybe rough-in goes faster than you estimate. Those insights let you tighten estimates where you are leaving money and stay competitive where you have room. Without phase data, you are guessing.
Old houses hide problems. Corroded fittings, unexpected framing, and code upgrades pop up mid-job. Each of these is a change in scope, and each should be documented and approved before the work proceeds, ideally with a short written change order that states the added cost. Verbal approvals tend to evaporate when the final invoice shows up higher than expected.
Record each change order as its own line in your job costing so you can see the original estimate, the approved additions, and the actual cost side by side.
When the final payment arrives, take a few minutes to compare actual hours and materials against the estimate and against what you billed. Note what was off and why. This habit feeds directly into better estimates, and it ties into the way supply house purchases are tracked, which we cover in supply house accounts and material markup.
Large plumbing jobs should not be financed by the plumber. Bill in stages tied to real milestones, cost the job by phase, document every change order, and review the results afterward. You will get paid faster, estimate more accurately, and sleep better during multi-day jobs.
911 Bookkeepers works with plumbing and trades contractors across the Baton Rouge metro and surrounding parishes, setting up job costing that matches how larger projects really run.
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