"CPS bids are won by 1.2% on average. When your labor pricing is right to the hour per MCAA unit and your takeoff is accurate on fixture rough-in and copper waste DWV, you can tighten margin without giving up protection. We went from 14% to 29% on CPS and the Cook County suburban districts. That's not luck. That's finally bidding the job instead of guessing it."
Stonebridge Plumbing & Mechanical was founded in 1998 by Michael Brennan and three fellow UA Local 130 journeymen who had spent the prior decade at a large Chicago mechanical house. They built the company around Illinois Plumbing License Law (225 ILCS 320) compliance and union wage discipline, and they've stayed tightly in that lane for 27 years. Today Stonebridge runs 180 employees out of a yard on the Southwest Side and a fabrication facility in Bedford Park, with full Illinois plumbing contractor licensure and a second mechanical division handling HVAC piping on combined scopes.
About 48% of Stonebridge's revenue is K-12: Chicago Public Schools capital plan work, plus suburban Cook County districts (District 214, CCSD 15, Elmhurst D205, and roughly a dozen smaller districts). The remainder is municipal, healthcare, and mid-market commercial. Every project Stonebridge touches is prevailing-wage, which means the bid-vs-win math is ruthlessly mechanical: the company that prices hours accurately wins.
Prevailing-wage plumbing bidding is not a margin fight — it's a labor-accuracy fight. The MCAA Labor Estimating Manual is the industry reference for productivity units: 0.8 hours to install a 1-1/2" copper DWV fitting, 1.4 hours for a standard water closet rough-in, and so on. Those units assume normal conditions. CPS buildings are anything but normal — cast-iron stack rehabs, lead-joint removals, 100-year-old masonry chases. Stonebridge's estimators were applying MCAA base units and then guessing at condition modifiers, which put their labor hours ±12% off actual build on any given school.
The second drag was fixture takeoff accuracy. A typical CPS renovation involves 120–180 plumbing fixtures across 4–6 floors, plus kitchen equipment rough-ins and gang-style group shower work. Counting fixtures off P-sheets is high-volume, error-prone, and exactly the kind of repetitive task that wears estimators out by 11 AM on bid day. Stonebridge tracked a 5–7% fixture count error rate on manual takeoffs — always under-counted, because estimators skip-ahead past symbols that "look the same."
The third, compounding issue was per-IPC-2021 (Illinois amended) compliance review. Every fixture rough-in has to reconcile against IPC 2021 water supply fixture units (WSFU) and drainage fixture units (DFU) for supply line and stack sizing. Late-stage design revisions that added two restrooms to a renovation floor plate routinely cascaded into main-stack upsizes that Stonebridge missed at bid, turning into uncompensated scope at build. Michael estimated those misses at roughly $41,000 per school.
Stonebridge piloted Pilrs in February 2025 on three parallel bids: a CPS elementary stack rehab, an Elmhurst D205 middle school HVAC piping scope, and a District 214 high school locker room renovation. Michael ran the bids through Pilrs and also had his chief estimator build conventional takeoffs. On fixture counts, Pilrs was inside 0.8% of verified counts — and caught 14 fixtures the chief had missed across the three packages. On copper DWV LF, Pilrs was 3.1% higher than manual; the delta resolved when Stonebridge cross-checked isometric sheets the chief hadn't opened.
The bigger unlock was MCAA-unit-level labor pricing. Pilrs applies MCAA Labor Estimating Manual units by fixture type and condition modifiers keyed to Stonebridge's prior-project actuals database, so labor hours come out with condition-adjusted MCAA units already applied rather than needing a second pass. The chief estimator now spends his time on bid strategy and margin calls rather than fixture counting. Three junior estimators who had been doing production takeoff were promoted to bid leads on mid-market commercial packages.
Production rollout completed May 2025. All K-12 and municipal bids run through Pilrs first; healthcare and commercial followed by September.
Fixture, rough-in, and fitting quantities come out mapped to MCAA Labor Estimating Manual units with condition modifiers.
Per-floor fixture unit totals reconcile against IPC 2021 supply and drainage sizing before the bid leaves the shop.
Exports push directly into Trimble AutoBid Mechanical with UA Local 130 wage rates and benefit structure preserved.
The win-rate number is the one Michael's board tracks. Jumping from 14% to 29% on K-12 bids across a 48-bid sample in 2025 added $6.4M of secured revenue against roughly the same volume of submitted bids. More importantly, the labor-variance number — how far Stonebridge's bid hours landed from field-actual hours — tightened from ±12% to less than 1%. On prevailing-wage work that variance is the difference between a profitable job and one that bleeds margin quietly across a six-month build.
IPC stack-sizing cascades stopped being a source of unrecovered scope. Pilrs flags every WSFU or DFU change that would push a stack size up one step, and surfaces that change before the bid ships. Stonebridge has tracked three schools through mid-build in 2025 where late-design restroom additions would have historically caused stack-resize change orders; all three were caught and priced correctly at bid.
Upload a plan set and see the same labor accuracy Stonebridge unlocked on prevailing-wage K-12 work. 14-day trial, no credit card required.