How Drawing Review Caught a Pipe Stack Clash on a Miami Custom Home

5 Cross-Discipline Errors on a Miami Home With No BIM Team

A custom home builder was getting ready to build a single-family residence in the Miami area. The design came from several consultants, each delivering their own PDF sheets. There was no BIM team on the job, so nobody was building a federated model or running clash detection.

There was also no formal QA/QC process. Coordination between the plumbing and electrical sheets depended on someone noticing a conflict by eye while flipping between sheets. On a one-off custom home, that someone is usually the project manager, who is also running the schedule and the subs.

Custom homes don't repeat. There is no prototype that has already been built once, so every wall, chase, and equipment location is being coordinated for the first time.

Helonic Found a $20,000 Stack and Subpanel Clash in One Wall

The builder uploaded the full PDF set. Helonic read the plumbing, electrical, structural, and architectural sheets together and compared where each discipline put its equipment and routes.

The finding that mattered most was a main plumbing stack drawn in the same wall as an electrical subpanel and its trunk feeder. The plumbing plan and the electrical plan each worked on their own. Overlaid, the stack and the panel could not both be there.

Moving the stack was not a one-sheet fix. The plumber had to route the main through a completely different set of walls, which changed the branch runs to the fixtures it served and the framing those walls needed to carry the pipe.

The same run listed four other items a custom home can't absorb. Each one sat between two consultants' sheets, which is where a set with no formal QA/QC lets things through.

Impact window and door sizes. The window and door schedule listed impact-rated units at sizes that did not match the rough openings drawn on the elevations. In the High-Velocity Hurricane Zone, each unit has to be a product with its own Miami-Dade approval, and that approval covers specific sizes and anchoring. A unit ordered to the schedule would not fit the opening, and one built to the opening might not match anything that has an approval. Impact products are made to order, so the error shows up weeks after the order, when the opening is already framed. Estimated cost if found in the field: about $18,000 in reordered units and lost time.

Finished floor elevation. The architectural sheets set the finished floor at one elevation, and the site plan for the flood zone called for a different one. That number drives the slab, the stem walls, the door thresholds, the driveway slope, and how many steps lead to the entry. If it is wrong, the fix is not an edit to a note. It changes the pour and the grading, and it can hold up the permit until the flood-zone documents agree with the plans. Estimated cost if found after the slab work started: about $25,000 in rework to the pour and grading, plus the delay.

Beam over an open room. A beam on the structural sheets landed on a wall that the architectural plan showed as open great room. Either the wall exists and the room is not open, or the room is open and the beam has no support below it. The load path had two answers depending on which discipline you read. The builder had to decide which was intended before framing, because a column or a bearing wall in the middle of a great room changes the design. Estimated cost if found after framing: about $12,000 to re-engineer the support and reframe.

Pool equipment pad. The pool equipment pad appeared on the site plan, but its slab was not on the structural sheets and its power was not on the electrical sheets. The pump, heater, and controls still need a circuit, a disconnect, bonding, and ground-fault protection. Without them on the drawings, the pool sub and the electrician each assume the other has it, and the pad gets sorted out in the field after the main electrical work is done. Estimated cost as a field change: about $6,000 for the slab, the circuit, and a second trip from the electrician.

See custom residential drawing review, Florida plan review requirements, hurricane-resistant construction drawings, what clash detection does not catch, 2D clash detection, and the Boston campus building review.

$80,000+ in Change Orders Stopped on Paper

The builder had the designers move the stack and re-route the plumbing before any wall was framed. They priced the field version of that same change at more than $20,000: opening finished walls, re-running pipe, moving the panel or the trunk line, and paying for re-inspection and the days lost.

Added to the stack, the four other findings bring the estimate to more than $80,000 in change orders: $20,000 for the stack, $18,000 for the impact windows and doors, $25,000 for the floor elevation, $12,000 for the beam, and $6,000 for the pool pad.

The other four findings went back to the design team as RFIs with the sheet references already attached. The window schedule was corrected to match the openings, the floor elevation was reconciled with the flood-zone plan, the beam and the great room were settled before framing, and the pool pad got its slab and its circuit on the drawings.

Without a BIM team, the builder still had a cross-discipline check on the set. The review took the place of the QA/QC pass the project never had.

A set with no BIM team and no QA/QC is where these conflicts survive. Across 1,000+ drawing packages Helonic has reviewed, about 8 in 10 had at least one coordination conflict between disciplines. See what Helonic found across 1,000+ drawing reviews.

Florida Building Code HVHZ and Flood Rules Behind $43,000 of the Findings

Miami-Dade and Broward counties are the High-Velocity Hurricane Zone under the Florida Building Code. In the HVHZ, every impact window and door needs product approval, usually a Miami-Dade Notice of Acceptance, for the size and anchoring installed.

That is why the window schedule mismatch carried $18,000. An approval covers specific sizes. A unit ordered to the schedule that does not fit the framed opening cannot be trimmed to fit, so it gets reordered, and impact products are made to order.

The finished floor elevation comes from the flood zone on the FEMA flood map and the local floodplain rules, which often require freeboard above the base flood elevation. The architectural sheets and the site plan have to agree before the permit and the elevation certificate will. That mismatch carried the other $25,000.

The pool equipment pad falls under NEC Article 680, which covers pool pumps, heaters, bonding, and ground-fault protection. Those circuits have to be on the electrical sheets for the electrician to price and the inspector to check.

“We had no BIM team and nobody doing QA/QC. The plumbing stack and the subpanel were in the same wall, and I would have found that with the walls framed. Moving it then is a $20,000 problem. On paper it was a markup.”

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