How Drawing Review Caught 5 Conflicts on an Omaha Grocery Store

A Prototype Grocery Store Built in Omaha From Another Region's Details

A general contractor was building a grocery store in Omaha for a national retailer. The design started from the retailer's prototype, a set of drawings and details reused store after store, adapted by a local design team for the site.

Grocery work comes in more packages than most buildings. The retailer issues its own fixture plan and owner-furnished equipment package, and those change during design. The prototype details were written for another region, and the civil, plumbing, and electrical drawings were drawn locally.

The slab pour was one of the first milestones, and everything under it had to match the store's final layout. The GC wanted the set checked before that pour.

Helonic Caught a Revised Fixture Plan a Week Before the Slab Pour

The GC uploaded the PDF set, the specifications, the fixture plan, and the retailer's vendor package. Helonic compared the drawings with each other, with the specs, and with the retailer's latest documents.

The first finding was under-slab rough-in that followed an old fixture plan. The retailer's fixture plan located the refrigerated cases, meat and deli prep, and floor drains. Plumbing sheet P-001 and electrical sheet E-001 showed the refrigeration piping trenches, indirect waste drains, and conduit to those case locations under the slab.

The retailer had issued a revised fixture plan that moved a run of dairy cases and swapped two aisles. The plumbing and electrical under-slab drawings still followed the old one. Floor sinks for indirect waste ended up in the middle of an aisle, and refrigeration trenches missed the new case locations by several feet.

Under-slab work is buried by the pour. Found after it, every miss means saw-cutting, trenching, and re-pouring a sales floor that is also the finished surface customers walk on. The GC priced it at $50,000 to $200,000 to saw-cut, trench, re-pour, and refinish, with 2 to 4 weeks of delay. Fixed before construction, it was $2,000 to $5,000.

The second was prototype footings and roof details that did not fit Omaha. The prototype structural details on S-501 showed perimeter footings 24 inches below grade. Omaha's frost depth is about 42 inches. The locally adapted general notes said 42 inches, but the typical details copied from the prototype still said 24, and footings that shallow can heave in winter.

The prototype roof plan placed rooftop units on standard 14-inch curbs near a step where the stockroom roof is taller than the sales floor. Snow drifts against that step far deeper than the base snow load. The prototype did not account for drift load on the joists near the step, and 14-inch curbs would be buried by drifts, blocking airflow and letting snowmelt in at the curbs.

The prototype was correct for the region it was drawn for, which is why nobody questioned it. Found in the field, footings formed at the wrong depth have to be dug out and re-poured, joists need reinforcement or replacement, and curbs have to be rebuilt. The GC priced it at $40,000 to $175,000 with 1 to 4 weeks of delay. Fixed before construction, it was $2,000 to $8,000.

The third was owner-furnished equipment that did not match the circuits. The spec section 01 64 00 and a responsibility matrix on the G-sheets said the retailer furnished the refrigeration racks, ovens, POS equipment, security cameras, and signage, and the GC installed and connected them. The electrical drawings sized circuits from the prototype's equipment data.

The retailer's current vendor package for this store used a different refrigeration rack, a larger bakery oven, and new self-checkout lanes. Their voltages, amperages, and locations did not match the electrical drawings. The responsibility matrix and the spec also disagreed on who provided the refrigeration piping between the racks and the cases.

Owner-furnished equipment usually arrives late. Finding the mismatch when it lands means new circuits, new breakers, sometimes a larger panel, and a scramble right before opening, and the piping gap becomes a change order and a dispute. The GC priced it at $30,000 to $150,000 with 1 to 3 weeks of delay, usually right before opening. Fixed before construction, it was $1,000 to $3,000.

The fourth was parking grades too steep for accessible stalls. The site plan on C-101 and the architectural site details showed accessible parking stalls, access aisles, and an accessible route to the entrance. The grading plan on C-201 sloped the parking field toward inlets.

Accessible stalls and aisles cannot exceed about 2% slope in any direction, and the accessible route has its own running and cross slope limits. The grading plan, drawn to move water off a large parking field, put 3% to 4% slopes through the accessible stalls and sloped the entrance walk past the cross slope limit.

Once paving is placed, the only fix is tearing it out and regrading, and retail parking lots are one of the most common targets of accessibility lawsuits. The GC priced it at $20,000 to $80,000 to remove and replace paving and regrade. Found after opening, the rework costs about the same, plus legal exposure. Fixed before construction, it was $1,000 to $3,000.

The fifth was a roof with no overflow drainage. The roof plan on A-401 showed a large low-slope roof inside a parapet with interior roof drains, and plumbing sheet P-201 sized the primary drains and leaders.

Roofs where a parapet can trap water need secondary drainage, either overflow drains or scuppers through the parapet, sized for the design storm. Plumbing showed primary drains only, and architectural showed no scuppers. In Omaha, snow and ice can block the primary drains, which is when overflow matters most. The structural design may also assume a maximum ponding depth that only holds if the overflows sit at a specific height.

Without secondary drainage, a blocked drain in a heavy storm can load the roof past its design. Adding scuppers after the parapet and roof are finished means cutting masonry or panels and re-flashing, and adding overflow drains means new interior piping over the finished sales floor. The GC priced it at $25,000 to $100,000 with 1 to 2 weeks of delay. Fixed before construction, it was $1,000 to $3,000.

See retail construction drawing review, Omaha plan check, owner-furnished equipment coordination, roofing detail failures, plumbing coordination, revision comparison, and the Dallas lab review.

$165,000 to $705,000 in Field Rework Fixed for $7,000 to $22,000

Helonic caught the fixture plan mismatch a week before the slab pour, while the under-slab layout was still a drawing revision.

Fixed before construction, the five came to $7,000 to $22,000. Found in the field, the GC priced the same five at $165,000 to $705,000.

The under-slab finding carried the hardest deadline. After the pour, the only fix runs through the finished sales floor.

The fixture plan, the vendor package, and the prototype details each came from a different source than the local drawings. 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.

Omaha Frost Depth, ASCE 7 Snow Drift, and Accessible Parking Slopes

Omaha permits commercial buildings under the International Building Code as adopted and amended by the city. The IBC requires footings to extend below the frost line unless they are protected from frost, and the local frost depth is about 42 inches.

Snow loads come from ASCE 7, which the IBC references. Where a higher roof sits next to a lower one, ASCE 7 requires the lower roof to carry a drift surcharge on top of the base snow load. A prototype drawn for a warmer region can carry a step in the roof without that drift.

The IBC requires secondary drains or scuppers wherever the roof edge extends above the roof and would trap water. ASCE 7 rain loads assume the primary drains are blocked, so the roof structure is designed for water up to the secondary drainage plus the depth flowing over it.

Accessible parking spaces and access aisles cannot slope more than 1:48, about 2%, in any direction under the 2010 ADA Standards. Accessible routes are limited to a 1:20 running slope and a 1:48 cross slope. Steeper running slopes have to be designed as ramps.

Owner-furnished equipment is connected under the National Electrical Code, and circuit sizes follow the nameplate of the equipment actually delivered. When the vendor package changes, the circuits have to change with it.

“The retailer moved the dairy cases on the latest fixture plan, but our under-slab plumbing and conduit still followed the old one. Helonic caught it a week before the slab pour. After the pour, that's a saw-cut through a brand new sales floor.”

Omaha Grocery Store Drawing Review: Questions and Answers