How Drawing Review Caught 5 Conflicts on a DFW Distribution Warehouse

A 500,000 Square Foot Tilt-Up Warehouse on North Texas Clay

An architect was finishing the drawings for a speculative distribution warehouse in Dallas-Fort Worth: about 500,000 square feet of slab, tilt-up concrete walls, high-piled storage, and more than 100 dock doors. The building had no tenant yet, so the leasing brochure promised it would suit a range of distribution users.

Warehouses look simple and carry a lot of separate packages. A panel engineer draws the tilt-up walls, a geotechnical engineer writes the soil recommendations, and the dock equipment, fire protection, and MEP drawings each come from someone else. North Texas adds expansive clay and long, hot summers.

Most of the expensive decisions on a tilt-up building get locked in early. The slab, the dock pits, and every opening in the panels are formed before the concrete is poured. The architect wanted the set checked before that happened.

Helonic Found a $500,000 to $2 Million Gap Between the Geotech Report and the Earthwork Spec

The architect uploaded the PDF set, the specifications, and the geotechnical report. Helonic compared the panel drawings, civil, structural, mechanical, plumbing, electrical, and fire protection sheets with each other, with the specs, and with the geotech recommendations.

The first finding was MEP openings missing from the tilt-up panels. Tilt-up panels are cast flat on the building slab and lifted into place, so every opening and embed has to be formed before the pour. The panel drawings, by a separate panel engineer, showed the dock door openings and structural embeds.

Mechanical showed wall louvers and exhaust fans for warehouse ventilation. Plumbing showed overflow scuppers and hose bibbs, electrical showed the service entrance conduits, and fire protection showed the fire department connection and riser penetrations. Many of those openings never made it onto the panel drawings, and others were shown at different locations than the MEP sheets.

The louvers mattered most. An unconditioned warehouse in a Texas summer depends on them, and the spec required a specific air change rate. Once panels are cast, every missing opening has to be saw-cut or cored through a structural panel, and the panel engineer has to confirm the rebar and lifting inserts are intact. Large louvers in the wrong place can need panel reinforcement or a redesign.

That was priced at $30,000 to $150,000 in the field, at $2,000 to $10,000 per opening plus engineering, with 1 to 3 weeks of delay. Fixed before the panels were cast, it was $1,000 to $3,000.

The second was subgrade treatment that did not match the geotech report. The geotechnical report said the North Texas clay under the site could swell several inches. To keep the slab from heaving, it recommended removing and moisture-conditioning the soil to 8 to 10 feet below the slab.

The earthwork spec section 31 23 00 and the civil grading plan in the bid documents called for 2 feet of select fill over compacted native soil. On 500,000 square feet of slab, the difference between 2 feet and 10 feet of soil treatment is an enormous quantity of earthwork, and it is often the single largest swing in a warehouse budget.

Found during earthwork, it is a change order of $500,000 to $2 million and a slip before the slab can be poured. Never found, the slab heaves and cracks over its first few years, on a floor that has to stay flat for forklifts and racking. That was priced at $1 million or more in slab repair, plus tenant disruption. Re-scoping the earthwork before bid was $5,000 to $15,000.

The third was a missing fire pump. Fire protection sheet FP-001 designed ESFR sprinklers for high-piled storage, which demand a large volume of water at high pressure. The hydraulic summary assumed the city main could supply it. Civil sheet C-401 showed an 8-inch fire line from the city main and noted the city's water flow test.

At the flow test's measured pressure, the city supply could not meet the ESFR demand plus the hose stream allowance. The building needed a fire pump. The site plan had no pump room, electrical had no fire pump feeder or dedicated service, and the fire protection drawings did not mention one.

A fire pump, its controller, the pump room, and a dedicated electrical feed are long-lead items, and the fire marshal will not approve occupancy without an adequate water supply. Found late, it can be the one item holding the certificate of occupancy for the whole building. That was priced at $250,000 to $600,000 for the pump, controller, room, feeder, and possibly a tank, with 8 to 20 weeks of delay. Fixed before construction, it was $5,000 to $15,000.

The fourth was roof collateral load short of what tenants were promised. The spec and the leasing brochure promised a building ready for distribution tenants, with room for hung conveyors, HVAC for conditioned areas, and heavier high-bay lighting. The structural general notes on S-001 designed the roof joists for a collateral load that covered only sprinklers, lights, and minimal ductwork.

The joists could not carry what the spec and the leasing materials said tenants could hang from the roof. The roof framing plan also did not identify which joists could take concentrated loads from future rooftop units or conveyors.

That surfaces when a tenant signs and their engineer checks the roof, usually against a tight move-in date. The fix is field-reinforcing joists across large areas of the building while the tenant waits, or losing the tenant to a competing building. That was priced at $100,000 to $500,000 with 4 to 10 weeks of fit-out delay. Fixed before construction, it was $2,000 to $10,000.

The fifth was dock pits and power that did not fit hydraulic levelers. The dock equipment spec section 11 13 19 called for hydraulic dock levelers with vehicle restraints at every door, each needing power for the pump, restraint, and controls. Structural sheet S-101 detailed the leveler pits at sizes copied from mechanical levelers on a previous project, and electrical sheet E-101 showed one convenience receptacle at each door.

Hydraulic levelers need different pit dimensions and capacities than mechanical ones, and each door needs a dedicated circuit for the leveler and restraint. Across more than 100 doors, the panelboards and feeders on the electrical drawings did not have the capacity.

Pits are formed when the slab is poured, so wrong sizes mean saw-cutting and re-forming the slab edge at every affected door, and adding circuits later means new panels and feeders along the whole dock wall. That was priced at $75,000 to $300,000, with pit rework at $1,000 to $3,000 per door plus circuits and panels, and 2 to 4 weeks of delay. Fixed before construction, it was $1,000 to $5,000.

See warehouse and logistics drawing review, Texas plan review requirements, Dallas plan check, tilt-up panel coordination, reading geotechnical reports, fire protection drawing review, loading dock coordination, fire and life safety checks, and the Dallas lab review.

$955,000 to $3.55 Million in Rework Fixed for $14,000 to $48,000

Helonic flagged all five before construction. The panel openings were caught before the panels were cast, and the earthwork gap before the bid.

Fixed at that stage, the five came to $14,000 to $48,000. Found in the field or at tenant fit-out, the same five were priced at $955,000 to $3.55 million.

The earthwork carried the largest swing, and the fire pump carried the longest delay. Either one alone was worth more than the review.

The earthwork spec, the roof joist design, and the dock pits each fell short of a document the project had already committed to. 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 what Helonic found across 1,000+ drawing reviews.

Expansive Clay, ESFR Water Supply, and Fire Pump Power on a DFW Warehouse

Texas has no statewide commercial building code, so each city adopts its own. Most Dallas-Fort Worth cities adopt the International Building Code with the regional amendments recommended by the North Central Texas Council of Governments.

The IBC requires foundations on expansive soils to be designed for the soil's volume change, or the expansive soil to be removed or stabilized. The geotechnical report sets how deep that treatment goes, which is why the earthwork spec has to carry the report's numbers.

ESFR sprinklers are designed under NFPA 13, and the water supply has to meet the sprinkler demand plus the hose stream allowance at the pressure the flow test measured. When the city main cannot, a fire pump installed under NFPA 20 makes up the difference.

Fire pump power falls under NEC Article 695, which requires a reliable source and limits how the feeder can be protected and disconnected. That is why a fire pump needs its own service or feeder shown on the electrical drawings.

Tilt-up panels are designed for the lift as well as the finished building, following guidance such as ACI 551. Openings change the panel's reinforcement and the location of lifting inserts, so they belong on the panel drawings before the pour.

“Our mechanical drawings had ventilation louvers in the tilt-up walls that never made it onto the panel drawings. Helonic caught every mismatch before the panels were cast. After the pour, each one is a saw-cut through a structural wall.”

DFW Distribution Warehouse Drawing Review: Questions and Answers