Reinforcement Placement Verification

Purpose

Reinforcement works by where it sits, not by how much came off the truck. Correct size, spacing and tonnage still behave like an unreinforced slab if the steel lies on the base, and nothing after the pour recovers it. The failures are quiet: mesh flat on the ground while the top of the panel opens; an inch of cover on an exposed slab that rusts and lifts a spall in year six; a lap shortened to use up a cut stick, so two bars never act as one; dowels fanned out of parallel so a joint locks instead of sliding and cracks the panel beside it. Each is invisible the moment concrete covers it, and each is an argument the shop loses, because the only evidence sits on the customer's side.

Scope

Covers placed reinforcement in cast-in-place residential and light commercial work - slabs on ground, footings, foundation walls, thickened edges, curbs and dowelled construction joints - from the last tie to the release of the steel for concrete.

It does not cover subgrade, base, forms, grade or joint layout, owned by the pre-pour checklist and subgrade verification SOP and already passing before this starts, nor dowels drilled into existing concrete, whose silica hazard routes to the silica dust control SOP, nor post-tensioned tendons, released only by the PT supplier. Where a special inspection is required, this record is what the crew hands that inspector, not a substitute for their sign-off.

Roles and responsibilities

Procedure

1. Read the drawing at the steel. On the pour, check the work order's five values against the reinforcing plan: bar size, grade, spacing each way, specified clear cover per face, lap length. Acceptance: all five match and are on the record; if the drawing is silent on lap, the figure comes from the engineer of record in writing. Wrong looks like a work order reading "rebar 16 on center" with no cover and no lap, which sends a placer to invent both; stop rule, measure nothing until the five values exist. Hazard: cap or bend over any vertical dowel a person could fall onto, per 29 CFR 1926.701(b) on construction sites.

2. Confirm the bar is the bar the drawing calls for. Read the rolled marks - mill, size, type, grade - on one bar per bundle and check size with a caliper on the plain barrel, because No. 4 and No. 5 look alike in a wet stack. Acceptance: marks recorded per bundle, matching the specified size and grade, with mill certificates where the specification calls for them. Wrong looks like Grade 40 delivered against a Grade 60 design, which the mark shows and the eye does not; stop rule, quarantine the bundle and call the supplier, and place a substitution only on the engineer's written approval. Hazard: bundles roll when banding is cut, so chock the bundle, stand clear of the roll direction, cut-resistant gloves on.

3. Check spacing across the mat, not at one bar. Measure center-to-center spacing at three locations in each direction, spread across the pour, and count total bars each way against the drawing. Acceptance: spacing within the ACI 117 tolerance your specification adopts and, more importantly, a bar COUNT at or above the drawing each way, because ACI 117 lets spacing move but does not permit the required number of bars to drop. Wrong looks like a mat that drifted wide and lost two bars at the far end; stop rule, add the missing bars first, since a drifted mat with the right count is a tolerance question and a short count is a design question. Hazard: an abrasive chop saw throws sparks and grinding particulate, so cut clear of the mat, form oil and curing blankets, with ANSI Z87.1 eye and face protection.

4. Verify laps by measurement. Measure the overlap at every top-mat splice and at a quarter of the splices elsewhere, and confirm splices are staggered rather than landing on one line. Acceptance: every lap at or above the drawing figure, converted from bar diameters to inches once on the record so nobody does arithmetic at each splice; a Class B tension lap under ACI 318 is 1.3 times the development length, near 40 to 50 bar diameters for common residential bar and mixes, but the drawing governs. Wrong looks like a short lap at the last splice of a run; stop rule, add a full-length lapper bar each side and re-tie, because touching bars are not a splice. Hazard: tie from a kneeling board with both hands free, since reaching into a tied mat pinches fingers between bar and chair.

5. Verify the support system before you verify cover. Walk the chairs and bolsters: specified height, bearing on a surface that will not punch, spaced so the bar does not deflect under a boot. Acceptance: support spacing per the bar support guidance your specification names, near 3 to 4 ft each way for No. 4 bar in flatwork with heavier bar spanning farther, and no sag when a crew member stands mid-span. Wrong looks like pointed chairs sinking into base compacted damp and since dried loose; stop rule, add supports until the stand test shows no sag, because the next step's reading means nothing if the steel moves underfoot. Hazard: nobody runs the stand test alone over an open trench or on an elevated deck.

6. Measure clear cover against both governing floors. Measure from the finished surface elevation, taken off the form top or screed string, to the top of the bar, at four points plus one per 400 sq ft, recording each location. Acceptance: every reading at or above the HIGHER of two floors - the ACI 318 cover minimum for that exposure, 1.5 in for No. 5 and smaller exposed to weather and 3 in cast against and permanently in contact with ground, and the drawing's specified cover less the ACI 117 minus tolerance, 3/8 in for a member of effective depth 8 in or less and never more than one third of the specified cover - with the governing floor written down. Wrong looks like a reading taken off the base instead of the finish elevation, which reads generous by exactly the amount the slab is thin; stop rule, re-chair and re-measure the failing point plus one each side, never averaging a failure against passing readings, because corrosion starts at the thinnest point. Hazard: keep the screed string taut and flagged so nobody walks into it at throat height.

7. Check dowels, edges and penetrations. Confirm joint dowels are the specified size and length, centered on the joint, parallel to the surface and to each other, greased or sleeved on one end only, and that thickened-edge, curb and penetration steel matches the drawing. Acceptance: alignment checked with a straightedge across four dowels, and no bar crossing an isolation joint. Wrong looks like a dowel basket run over by a skid steer, leaving dowels fanned, which locks the joint and cracks the panel beside it; stop rule, re-set and re-check. Hazard: dowel grease is a petroleum product, so read its SDS, wear the glove type it names, and keep the container off the steel where a spill kills bond.

8. Release the steel, or hold it, in writing. With every value recorded, the crew leader signs the release. Acceptance: no open item, any third-party inspection completed or scheduled ahead of concrete, release time entered. Wrong looks like a verbal "we are good" phoned in while two corners are still being re-chaired; stop rule, a hold is a hold, and the office calls the plant, not the crew leader mid-pour. Hazard: foot traffic continues on the mat after release, so walk boards, impalement caps and the exclusion of wheeled equipment stay in place through placement.

The record this produces

One verification record per pour, completed on site before release. Fields: job and pour identifier, date, crew leader; the five design values from step 1 and their source; rolled marks per bundle; measured spacing at three locations each way plus total bar count each way; measured lap at each top-mat splice with the drawing figure beside it; support type, height, spacing and stand-test result; every cover reading with its location, both governing floors and which one governed; dowel size, alignment and sleeve confirmation; two photographs with a tape in frame; and the release signature and time, or the hold with the failing value named.

It lands on the job record in the office, not a truck cab. The inspector spot-checks two recorded points instead of re-measuring the pour. The office reads it years later when a spall shows up and the question is whether the steel was where the design put it. The estimator reads it across jobs, because a shop that keeps finding cover short has a chair-ordering problem.

One pass, with a step that failed

A light commercial rear apron, 38 ft by 22 ft, 6 in slab on ground, No. 4 Grade 60 at 16 in on center each way, specified clear cover 2.0 in from the finished surface, drawing lap 25 in. Area is 38 x 22 = 836 sq ft, so step 6 needs 4 points plus 836/400 rounded up, which is 3 more: 7 minimum. The crew took 8.

Steps 1 through 4 passed. Marks on one bar per bundle read size 4, grade 60. Spacing measured 16.0, 16.25 and 15.75 in long and 16.0, 16.0 and 16.5 in short, with 17 bars long and 29 short, matching the drawing. Nine top-mat splices measured 25 to 27 in against the 25 in figure.

Step 6 failed. Cover read 2.0, 1.9, 2.1, 2.0, 1.75, 2.0, 1.0 and 1.9 in. Both floors went on the record: ACI 318 gives 1.5 in for No. 5 and smaller exposed to weather; ACI 117 gives 2.0 less 3/8, which is 1.625 in, with the one-third check at 0.67 in and therefore not binding. The higher floor, 1.625 in, governed. Seven of eight passed. The 1.0 in reading, 6 ft in from the north form beside a doorway, failed both floors, not only the tighter one.

The crew leader went back to step 5 rather than forward. Two chairs there had punched into base wetted for compaction and since dried loose, and the bar had dropped roughly an inch over about a 5 ft run. The fix was six more supports at 2 ft centers on plate-footed bolsters. The re-measured point read 1.95 in, and the two flanking points the stop rule requires read 2.0 and 1.9 in. Steps 7 and 8 then ran clean. Release signed at 15:40 for an 07:30 load.

What skipping step 6 buys is not a crack. It is 1.0 in of cover on a slab that takes deicing salt, putting the bar inside the chloride front years earlier than the design assumed, arriving as a rust stain and then a spall lifting along the bar line, in a doorway the customer uses daily.

When the site does not match the drawing

Supplier shorted the bar size: place nothing and get a written substitution, because a heavier bar at the same spacing changes cover and a lighter one changes the design. Another trade cut the mat for conduit: re-tie to the drawing, and where the penetration is not drawn, the engineer sets the trim steel. Someone pushes to pour over a hold: the hold stands, and the call names the failing value, its floor and a new date. Steel finished after the truck arrives: the load is turned.

References

• ACI 318, Building Code Requirements for Structural Concrete, cover by exposure and lap splice provisions, in the edition your building department has adopted. See related: the ACI 318 minimum cover for residential rebar card in this library.
• ACI 117, Specification for Tolerances for Concrete Construction and Materials, placement tolerance on cover and effective depth, in the edition your project specification adopts.
• CRSI bar support and placing guidance for support type, height and spacing.
• 29 CFR 1926.701(b), reinforcing steel impalement protection on construction sites.
• See related: the pre-pour checklist and subgrade verification SOP.