On a tenant upfit the plumbing is rarely the largest cost and frequently the reason the certificate of occupancy slips. It appears three separate times, and every one of them is on another trade's critical path.
Before the bid: the site walk
Existing conditions decide the price. Where the stacks are, what the slab is and what is in it, whether the water service has capacity, and whether the existing assemblies are compliant. A bid produced from drawings alone on an existing building is a bid that will change.
Where it slips: nobody cameras the existing waste, and the condition of the line becomes a change order at rough-in.
Phase 1 — Underground (if there is one)
Typically 3–7 days, and it must complete before the slab pour.
Waste and vent below slab, water service in, set out exactly to plan, pressure tested and inspected before concrete covers it. This is the least forgiving phase on the whole job.
Where it slips: the inspection is not booked far enough ahead and the pour waits on it.
Phase 2 — Rough-in
Typically 1–3 weeks, after framing and before drywall.
Supply, DWV and gas through the framing, fixture carriers set, everything pressure tested and inspected. Drywall cannot start until this passes.
Where it slips: the equipment schedule changes after rough-in has started. A different dish machine or a relocated hand sink is a cheap change on paper and an expensive one in a stud wall.
Phase 3 — Trim-out
Typically 3–7 days, after finishes.
Fixtures, water heater, equipment connections, final test and final inspection.
Where it slips: fixture lead times. This is the single most common cause of a late CO on the jobs we work, and it is entirely visible at bid stage if anyone checks.
The three things that actually keep it on schedule
- Book inspections early. Inspector availability is not something anyone can compress on the day.
- Lock the equipment schedule before rough-in. Every change after that point is in a wall.
- Order long-lead fixtures at bid award. Not at trim. A specialty fixture with a fourteen-week lead will hold up a completed building.
What a good bid gives you
Durations against each phase, not just a lump sum. Fixture allowances itemised separately. Permit and inspection responsibilities in writing. And any existing-condition code items called out before you sign.