How Drawing Review Caught 847 Issues on a Bay Area Tower

847 Issues Across 340 Sheets on a 24-Story Tower

A mid-size general contractor was coordinating a 24-story mixed-use tower: ground-floor retail, six levels of parking, and 18 floors of residential above. The set was 340 sheets across architectural, structural, mechanical, electrical, plumbing, and fire protection, produced by four design firms.

Preconstruction was spending three weeks on each review cycle. Coordination meetings kept finding the same conflicts: HVAC ducts through structural beams, electrical panels behind plumbing risers, and architectural details that did not match the structural sections.

Permit was close, and two more revision cycles were still expected. The team needed a shorter review without dropping sheets.

Helonic Listed 312 Structure-MEP Conflicts in About an Hour

They uploaded all 340 sheets and ran one multi-discipline check. Helonic read the set in about an hour. A manual pass of the same scope had been taking about three weeks.

The report listed 847 issues. The ones that cost money were 312 conflicts between structure and MEP and 346 mismatches between architectural details and structural sections. Code notes were the smaller remainder.

The critical items went into Procore as RFIs, each tagged to the design firm that owned the sheet, with the sheet reference already attached.

See mixed-use construction drawing review, California plan check requirements, mixed-use vertical stacking coordination, seismic bracing coordination, 2D clash detection, and the New York office building review.

$320,000 in Rework Avoided Before the Next Submittal

The team confirmed 94% of the 847 findings as real coordination problems. The other 6% were low-confidence items they dismissed.

They put the avoided rework at $320,000, mostly MEP routes that would have meant field changes to structural penetrations.

Instead of sending RFIs out over several weeks, they issued 127 in one batch. Design responses came back faster, and the permit date held.

This tower was typical. Across 1,000+ drawing packages Helonic has reviewed, about 8 in 10 had at least one coordination conflict between disciplines. See how often construction projects go over budget.

California Building Code and Seismic Rules Behind the 312 Structure-MEP Conflicts

Bay Area towers are permitted under the California Building Code, Title 24 Part 2. It adopts the International Building Code with state amendments, and cities such as San Francisco and Oakland add their own local amendments.

Most of the Bay Area sits in a high seismic design category under ASCE 7, which the CBC references for loads. That raises the cost of a duct through a beam. A field opening in a beam that is part of the lateral system needs the engineer of record to check it, and some locations cannot be opened at all.

Duct and pipe routing falls under the California Mechanical Code and the California Plumbing Code, which are based on the UMC and the UPC. Those codes set clearances and supports. The structural drawings set where a penetration may go. The 312 conflicts sat where those two sets of documents disagreed.

A mixed-use tower also stacks three uses: retail, parking, and residential. Each change of use is a place where the structure changes and the MEP routes have to change with it.

“We used to spend three weeks passing redlines between disciplines. Helonic gave us the cross-discipline list in half a day, and the Procore push saved the project engineers from typing each RFI by hand.”

Bay Area Mixed-Use Drawing Review: Questions and Answers