ACI 318 governs the design and detailing of structural concrete in the United States. At 600+ pages, it covers everything from material properties to seismic detailing, and plan reviewers know exactly where engineers cut corners. Most rejections are not design capacity failures. They are detailing and documentation omissions that make it impossible to verify the design from the drawings alone.
These are the eight findings that show up most frequently in concrete drawing reviews, with exact ACI 318-19 section references.
1. Development and lap splice lengths not shown or incorrect
Sections 25.4 and 25.5 require that reinforcement be developed or spliced to transfer forces between the steel and concrete. This is the single most common finding on concrete drawings. The errors take several forms:
| Error | Why it fails review |
|---|---|
| Lap splice lengths not shown on sections or details | Contractor has no basis for bar placement. Reviewer cannot verify adequacy. |
| Using a generic 40db for all bars | Development length depends on bar size, concrete strength, cover, spacing, coating, and lightweight factors (Section 25.4.2.3). A blanket value is almost always wrong for at least one condition. |
| Class B splices not identified where required | Section 25.5.2 requires Class B (1.3 x ld) when more than half the bars are spliced at the same location, which is the case in most slab and wall pours. |
| Missing top bar factor | Bars with more than 12 inches of concrete cast below them require a 1.3 factor (Section 25.4.2.4). Missed on beam top bars routinely. |
2. Concrete cover not specified or inconsistent
Section 20.5.1 and Table 20.5.1.3.1 specify minimum cover based on exposure, member type, and bar size. Reviewers check that the cover shown in sections matches the tabulated requirement and that it is consistent across the drawing set. Common problems:
Footings cast against earth require 3 inches. Formed surfaces exposed to weather require 1.5 inches for #5 bars and smaller, 2 inches for #6 and larger. Interior slabs require 0.75 inches. When the general notes say "1.5 inch cover unless noted otherwise" but the footing details show 2 inches, the reviewer flags the conflict.
3. Missing or inadequate seismic confinement in columns
For buildings in Seismic Design Category D, E, or F, Section 18.7.5 requires closely spaced transverse reinforcement (hoops) in the plastic hinge regions of special moment frame columns. The confinement zone extends from each joint face for a distance not less than the largest of: the column depth, one-sixth of the clear span, or 18 inches.
This also applies to intermediate moment frames (Section 18.4.3) with slightly relaxed limits. The reviewer will check that the column schedule distinguishes between confinement zone spacing and mid-height spacing.
4. Beam-column joint reinforcement omitted
Section 18.8 requires transverse reinforcement through the beam-column joint for special moment frames. Engineers sometimes detail the column confinement zones above and below the joint but leave the joint itself bare on the drawings. The joint shear check (Section 18.8.4) must be satisfied, and the required hoops must be shown on a joint detail.
For intermediate moment frames, Section 18.4.4.1 allows reduced joint reinforcement but still requires hoops through the joint at a maximum spacing of 8 inches.
5. Shear reinforcement spacing violations
Section 9.7.6.2.2 limits stirrup spacing in beams to the lesser of d/2 or 24 inches. When shear demand is high (Vs exceeds 4√f'c bwd), Section 9.7.6.2.2 cuts the limits in half: d/4 or 12 inches. Reviewers calculate the shear demand from the loading and check that the stirrup spacing on the beam schedules matches.
| Condition | Max spacing | Reference |
|---|---|---|
| Standard shear | d/2 or 24 in. | 9.7.6.2.2 |
| High shear (Vs > 4√f'c bw d) | d/4 or 12 in. | 9.7.6.2.2 |
| Torsion required | lesser of ph/8 or 12 in. | 9.7.6.3.3 |
| Seismic (special moment frame) | d/4, 8db, 24dtie, or 12 in. | 18.6.4.4 |
6. Shrinkage and temperature reinforcement missing in slabs
Section 24.4 requires minimum shrinkage and temperature reinforcement in structural slabs where flexural reinforcement runs in one direction only. The minimum ratio is 0.0018 for Grade 60 deformed bars (Table 24.4.3.2). This is frequently omitted on one-way slab details where the engineer focuses on the primary reinforcement and forgets the perpendicular direction.
7. Foundation-to-column dowel detailing incomplete
Section 16.3 covers the interface between a column and its footing. The longitudinal column bars must be developed into the footing (Section 16.3.5), and the footing must have adequate development length for the dowels. Common findings:
Hooked dowels are shown but the hook development length (Section 25.4.3) does not fit within the footing depth. Straight dowels are shown but the footing is too shallow for straight bar development. The detail shows dowels but does not specify the hook type (90-degree vs. 180-degree) or the extension beyond the hook.
8. Structural integrity reinforcement not addressed
Section 8.7 (cast-in-place) and Section 8.8 (precast) require structural integrity reinforcement to provide an alternate load path in case of localized failure. For cast-in-place construction, Section 8.7.4 requires at least two bottom bars to be continuous or spliced through the support in beams. For perimeter beams, top reinforcement must also be continuous.
How Callout helps
Callout reviews structural concrete drawings against ACI 318-19 alongside IBC, ASCE 7, and AISC 360 in a single pass. It flags missing development length tables, cover inconsistencies, confinement zone omissions, and spacing violations with exact section citations. Every finding includes a confidence rating so you know which items to verify first.