How Drawing Review Caught $310K on a New York Office Building

A 14-Story Office Tower Where Door, Slab, Beam, and Ceiling Drawings Disagreed

A general contractor was preparing to build a 14-story office building in New York. The structure was concrete with post-tensioned slabs and steel framing at the core. The floors were set up for open office tenants, with furniture power, a dense ceiling, and card access at every tenant entry. The drawing set ran 213 pages.

Most of the risk sat in the typical floor. A conflict drawn once on a typical plan gets built on every level, so one miss turns into the same field fix 14 times.

The contractor wanted those conflicts settled with the design team before buyout, while a fix was still a drawing revision.

Helonic Found $110,000 in Door Conflicts and $80,000 in PT Slab Penetrations

The contractor uploaded the full 213-page PDF set, the door hardware schedule, and the specifications. Helonic compared each discipline's plans with the structural notes and the schedules, and flagged places where two or more documents gave different answers for the same element.

The most expensive finding was the tenant entry doors. The hardware schedule called for electric strikes. The security drawings showed maglocks at the same doors, and maglocks bring their own egress requirements: a request-to-exit device and release on fire alarm. The electrical plans showed no power at any of those doors. Three documents gave three answers, and the contractor priced sorting it out in the field at about $110,000.

The second was core drilling through the post-tensioned slabs. The structural notes prohibited coring without GPR scanning and approval from the engineer of record. The plumbing plans showed floor drains and risers, and the electrical plans showed floor boxes for the open office furniture. The structural sheets showed no sleeve locations for any of them. Scanning and relocating every penetration after the pour was estimated at about $80,000, and a cut tendon would have cost far more.

The third was ductwork through beam webs. The mechanical plans ran a round supply duct through steel beams near the core. The structural drawings showed no web openings there, and where they did, the openings sat near the beam ends or went past the size limits in the structural general notes. Each crossing needed reinforcing plates or a reroute, about $60,000.

The fourth was the reflected ceiling plan. The architectural RCP set light fixtures on a grid. The mechanical plans put linear slot diffusers on the same lines as the linear lights, and the sprinkler spacing landed heads on light fixtures. Audio-visual and fire alarm speakers had nowhere left to go. Each conflict was small, but there were hundreds per floor, about $60,000 in total.

Helonic also flagged that the typical floor plenum did not work. The main duct, sprinkler branches, and light fixtures were drawn into a space under the beams that came up several inches short. The contractor did not price that one separately, because it was resolved with the engineers before anything was bought.

See commercial construction drawing review, New York plan review requirements, above-ceiling coordination, tenant improvement coordination, penetration analysis, and the Bay Area tower review.

$310,000 Across 4 Issues, Resolved With the Engineers Before Buyout

The contractor sent each finding to the design team as an RFI, with the sheets and the conflicting values marked.

The door hardware, security, and electrical drawings were brought to one locking scheme with power and egress devices shown at every tenant entry. The structural sheets picked up sleeve locations for the floor drains, risers, and floor boxes.

The beam penetrations were moved, resized, or reinforced within the structural limits. The RCP was recoordinated so lights, diffusers, sprinklers, and speakers each had a place, and the plenum was reworked on the typical floor.

These four were among many issues Helonic found on the set. Together they came to $310,000 in field rework: $110,000 for the door hardware, $80,000 for the slab penetrations, $60,000 for the beam openings, and $60,000 for the ceiling.

Seven disciplines plus a hardware schedule put this set toward the dense end. Across 1,000+ drawing packages Helonic has reviewed, sets with nine disciplines carried about 1.7 times the issue density of sets with four or fewer. See what Helonic found across 1,000+ drawing reviews.

Egress Locking Rules, ACI 318, and AISC Web Openings on a 14-Story Office

In New York City, buildings are permitted under the New York City Building Code. Elsewhere in the state, the governing code is the state Uniform Code, based on the International Building Code. Both regulate electrically locked egress doors.

A maglock on an egress door needs a release on the egress side, release on fire alarm, and release on loss of power. That is why the lock choice had to show up on three documents at once: the hardware schedule, the security drawings, and the electrical plans.

Post-tensioned slabs follow ACI 318, and the structural notes on this job prohibited coring without GPR scanning and the engineer's approval. A sleeve placed before the pour is the only penetration that needs neither.

Openings in steel beam webs are designed under AISC guidance, Design Guide 2 for steel and composite beams with web openings. Size and location limits keep openings away from beam ends, which is where several of these ducts crossed.

“Helonic caught that our typical floor plenum didn't work: the main duct, sprinkler branches and light fixtures were drawn into 26 inches under the beams with about 8 inches too little room. On a 14-story building, that would have been the same field fix 14 times. We resolved it with the engineers before buyout.”

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