How Drawing Review Caught 5 Conflicts on a Dallas Life Science Lab

Five Lab Conflicts Between Structure, MEP, Code, and the Specs in Dallas

A general contractor was preparing to build a multi-story life science building in Dallas. The lab floors carried fume hoods, lab gases, acid waste, and emergency eyewashes and showers. The building sat on a structural slab over drilled piers, which is standard on North Texas expansive clay.

Lab buildings put more systems in the same space than almost any other building type. They also spread those systems across more documents: the code analysis, the life safety plans, the controls spec, the fume hood spec, and the casework spec all describe parts of the same room.

The GC wanted those documents reconciled before buyout, while a fix was still a drawing revision. Lab equipment lead times leave little room to fix anything later.

Helonic Found $100,000 to $400,000 in Lab Airflow Scope Gaps Before Buyout

The GC uploaded the PDF set and the specifications. Helonic compared the architectural sections, the structural framing, and the mechanical, plumbing, fire protection, and life safety drawings with each other, with the specs, and with the code analysis.

The first finding was the ceiling zone at the lab and office transition. The sections on A-301 showed 16'-0" floor to floor with a 10'-0" ceiling in the labs. W24 girders crossed that zone, leaving about 3'-6" of usable depth. Mechanical ran a 60x30 supply main and a 54x28 exhaust main through it, and with insulation and hangers the two ducts needed nearly all of that depth. Fire protection mains, a 4" acid waste line, lab gas piping for CO2, nitrogen, vacuum, and compressed air, and 24" cable tray all had to cross the same zone.

The acid waste line has to slope continuously, so it could not hop over the ducts. Each system was drawn on its own sheet at its own assumed elevation, so the stack-up only showed when the sections were overlaid. Lab exhaust duct is heavy gauge and often welded or coated, so it is expensive to remake. A field reroute also changes static pressure, which can push the exhaust fans out of their selection range.

The GC priced that conflict at $75,000 to $300,000 in the field for duct remake, beam penetrations, and fan reselection, with 3 to 6 weeks of delay. Fixed in preconstruction, it was $5,000 to $15,000.

The second was plumbing under a structural slab on expansive clay. North Texas clay can swell and shrink several inches. Following the geotechnical report, S-101 showed the slab suspended over void forms on drilled piers so it would not move with the soil. P-001 buried the sanitary, lab waste, and acid waste piping in the soil below it, with standard rigid connections up through the slab.

Pipe in the soil moves with the clay while the slab stays put, and that shears the connections at the penetrations. The plumbing spec and the geotechnical report called for the piping to hang from the underside of the slab, or for flexible connections and sleeves sized for the predicted movement. The drawings showed neither.

This one rarely fails during construction. It fails after occupancy, as cracked drain lines under a finished lab floor, and the repair means saw-cutting a structural slab in an operating lab. Acid waste leaking into the soil is also an environmental problem. The GC priced it at $3,000 to $10,000 in preconstruction, $40,000 to $150,000 before the pour, and $250,000 to more than $1 million after occupancy, plus lab downtime and remediation.

The third was hazardous material control areas on level 4. The code analysis on G-002 used IBC control areas so the labs could store flammable liquids and other hazardous materials without becoming an H occupancy. The life safety plans, LS-101 through LS-104, showed the same lab layout, the same control area count, and the same 1-hour fire barriers on every floor.

The IBC reduces both the number of control areas and the allowed quantities as floors go up, and it requires 2-hour fire barriers between control areas on the fourth floor and above. The level 4 plan showed 1-hour barriers. Mechanical ran ducts across those barriers with no fire dampers, and the architectural wall types did not match either.

A top-floor tenant that cannot store the chemicals its program assumes can walk away from the lease. Upgrading walls from 1-hour to 2-hour after framing means new rated assemblies, dampers, and penetration firestopping. The GC priced that at $50,000 to $200,000 in the field, with 2 to 6 weeks of delay and a possible hold on the floor's TCO. Fixed in preconstruction, it was $2,000 to $8,000.

The fourth was tempered water at the emergency eyewashes and safety showers. The plumbing plans connected each station to the domestic cold water line in the ceiling, and the fixture schedule listed standard combination units. The spec required ANSI Z358.1, which calls for tepid water, roughly 60°F to 100°F, for the full 15-minute flush.

In a Dallas summer, cold water in a ceiling plenum, near the roof, or entering from shallow site piping regularly runs above 100°F. The spec required a thermostatic mixing valve with cooling capability or a tempered water loop. The drawings showed neither, and a safety shower that delivers hot water to someone covered in a chemical is a real injury risk and an OSHA exposure.

A building this size typically has 15 to 40 stations. Adding tempered water after the ceilings close runs $2,000 to $5,000 per station plus the loop, which the GC priced at $40,000 to $150,000 and 2 to 4 weeks. Fixed in preconstruction, it was $1,000 to $3,000.

The fifth was lab airflow controls. Specs 23 09 00 and 23 36 00 called for venturi-type lab airflow valves on every fume hood and on the lab supply and exhaust, with fume hood monitors, sash position sensors, and room pressure offsets that keep the labs negative to the corridors. The mechanical schedule listed standard pressure-independent VAV boxes, and the electrical drawings showed no power at the fume hood monitors.

The scope was split three ways. The fume hood spec assumed the hood manufacturer would provide the monitors, and the controls spec assumed the controls contractor would. The mechanical sub was pricing a different kind of terminal unit altogether.

Lab airflow valves have long lead times, and the system has to pass fume hood certification and room pressurization testing before scientists can move in. The GC priced valve replacement, controls rework, and change orders between subs at $100,000 to $400,000 in the field, with 6 to 16 weeks for lead times and recommissioning. Fixed in preconstruction, it cost $0 to $3,000.

See life science and laboratory drawing review, Texas plan review requirements, laboratory construction drawing review, pharmaceutical cleanroom coordination, spec analysis, and the Houston hospital MEP review.

$305,000 to $1.2 Million in Field Rework Fixed for $11,000 to $39,000

Helonic flagged all five conflicts before buyout, while each one was still a drawing revision.

Fixed at that stage, the five came to $11,000 to $39,000. Found in the field, the GC priced the same five at $305,000 to $1.2 million, and the slab piping alone could pass $1 million if it failed under an occupied lab.

The airflow controls carried the largest schedule risk. Wrong terminal units found in the field mean a reorder on long lead times and a second round of commissioning, which the GC put at 6 to 16 weeks before scientists could move in.

The airflow controls and the eyewash water were drawings that did not carry what the specs required. Across 1,000+ drawing packages Helonic has reviewed, about 6 in 10 sets with specifications had at least one conflict between the drawings and the project manual. See submittal review time benchmarks.

IBC Control Areas, ANSI Z358.1, and ASHRAE 110 on a Dallas Lab Building

Dallas permits commercial buildings under the International Building Code with city amendments. Labs that store hazardous materials use the control area provisions in IBC Section 414 to stay out of a Group H occupancy.

Those provisions tighten with height. The first floor allows four control areas at the full maximum allowable quantity. Floors four through six allow two control areas per floor at 12.5% of that quantity, separated by 2-hour fire barriers. A lab program that assumes ground-floor quantities on level 4 will not pass.

OSHA 29 CFR 1910.151 requires drenching and flushing facilities wherever eyes or skin may be exposed to corrosive materials, and ANSI/ISEA Z358.1 sets how those facilities perform. It calls for tepid water for the full 15-minute flush. In North Texas, that usually means a cooling-capable mixing valve or a tempered water loop.

Lab ventilation follows ANSI/ASSP Z9.5, and fume hoods are tested to ASHRAE 110 before the lab is accepted. Both depend on the airflow valves and controls actually installed, which is why the wrong terminal units hold up occupancy as well as costing money.

Expansive clay has no single code section. The geotechnical report sets the expected movement, and the structural and plumbing drawings have to carry it. That is why the slab piping conflict sat between the geotechnical report, the plumbing spec, and P-001.

“Our lab airflow spec called for venturi valves and hood monitors; the mechanical schedule called for standard VAV boxes, and nobody was carrying power to the monitors. Helonic flagged it before buyout. With those lead times, finding it in the field would have pushed our lab commissioning by months.”

Dallas Life Science Lab Drawing Review: Questions and Answers