Introduction
This is a hypothetical, illustrative example — not a real project, real client, or real site. All dimensions, designs, and costs are invented to demonstrate the estimating method end to end. Your project’s numbers will differ; the procedure is what transfers.
The scenario: a single-story detached garage, 24 ft × 28 ft (7.3 m × 8.5 m), on a continuous strip footing. The structural drawings (hypothetical) call for a 24-in-wide × 12-in-deep footing with 3 #5 Grade 60 longitudinal bars (bottom), #4 cross bars at 24 in on center, 3-in cover, 40-diameter lap splices, and 20-ft sticks. The Foundation Rebar Calculator is the tool used throughout — here’s the full manual pass so every number is checkable. The step-by-step method is also documented in the estimating guide.
The (Hypothetical) Project
- Structure: 24 × 28 ft single-story garage, slab-on-grade inside the footing loop
- Footing: continuous strip, 24 in (610 mm) wide × 12 in (305 mm) deep, perimeter loop
- Longitudinal steel: 3 #5 Grade 60 bars, bottom of section
- Transverse steel: #4 cross bars at 24 in on center
- Cover: 3 in (75 mm) all soil-facing sides
- Lap splices: 40 × bar diameter; sticks 20 ft (6.1 m)
- Waste allowance: 10%
Step 1: Footing Runs
The perimeter is a closed rectangle, and the trap is measuring the outer perimeter: 2 × (24 + 28) = 104 ft double-counts the four corners. The correct method is four non-overlapping rectangles. Verify with areas: outer 28 × 24 = 672 ft²; inner opening (28 − 4) × (24 − 4) = 24 × 20 = 480 ft²; concrete area = 672 − 480 = 192 ft². As non-overlapping runs: two long runs of 28 × 2 ft = 112 ft², plus two short runs of (24 − 4) × 2 = 20 × 2 ft = 80 ft²; 112 + 80 = 192 ft² ✓. So the runs are 28, 28, 20, and 20 ft — 96 ft total (equivalently, the centerline perimeter: 2 × (26 + 22) = 96 ft).
Lesson demonstrated: outer perimeter (104 ft) vs non-overlapping runs (96 ft) is an 8% swing before a single bar is counted. Always split the plan into non-overlapping rectangles — the common mistakes guide covers this in detail.
Step 2: Longitudinal Steel
3 #5 bars × 96 ft = 288 ft raw. Unit weight: 25 ÷ 24 = 1.043 lb/ft.
Step 3: Lap Splices
Per run, per bar line: Run A (28 ft): 28 ÷ 20 = 1.4 → 2 sticks → 1 lap. Runs C/D (20 ft): exactly 1 stick → 0 laps. Total laps per line: 1 + 1 + 0 + 0 = 2 laps. Lap length = 40 × 5/8 in = 25 in = 2.083 ft. Lap steel = 3 lines × 2 laps × 2.083 ft = 12.5 ft.
Longitudinal total: 288 + 12.5 = 300.5 ft of #5 → 300.5 × 1.043 = 313.4 lb (142.2 kg).
Step 4: Transverse Steel
#4 cross bars at 24-in spacing, bar length = 24 − 2×3 = 18 in = 1.5 ft. Count per run with the +1 rule: Run A: (28×12) ÷ 24 = 14 intervals + 1 = 15 bars; Run B: 15 bars; Runs C/D: (20×12) ÷ 24 = 10 + 1 = 11 bars each. Total = 15 + 15 + 11 + 11 = 52 bars × 1.5 ft = 78 ft of #4. Weight: 78 × 0.668 = 52.1 lb (23.6 kg).
(Corner bars — four L-shaped #5 corner ties — add as a separate line: 4 bars × ~4 ft = 16 ft ≈ 16.7 lb. Included below.)
Step 5: Totals, Waste, and Order
| Item | Length | Weight |
|---|---|---|
| #5 longitudinal + laps | 300.5 ft | 313.4 lb (142.2 kg) |
| #5 corner bars (4) | 16.0 ft | 16.7 lb (7.6 kg) |
| #4 cross bars (52) | 78.0 ft | 52.1 lb (23.6 kg) |
| Subtotal | 394.5 ft | 382.2 lb (173.4 kg) |
| With 10% waste | — | 420.4 lb → 421 lb (191 kg) |
Stick order: #5: 316.5 ft ÷ 20 = 15.8 → 16 sticks (×1.10 ≈ 18 with waste). #4: 78 ÷ 20 = 3.9 → 4 sticks (×1.10 ≈ 5 with waste). Accessories: ~200 loop ties (16-gauge), ~40 dobies/chairs (every 4–5 ft under 96 ft of runs, both… single bottom layer: 96 ÷ 4.5 ≈ 22 positions — order 30), tie spinner.
Delivery and Site Logistics (Illustrative)
The order — 18 sticks of #5, 5 sticks of #4, plus accessories — weighs about 421 lb (191 kg) and includes 20-ft lengths. A flatbed or long-bed truck handles it; the hypothetical site needs a clear 25-ft straight path from the road to the storage spot. Bars go onto timber dunnage, not bare soil, and the bundle gets tarped if rain threatens before tying day. Two people unload in under half an hour. Because the whole order rides one truck, the single delivery charge from the budget above is the only freight cost — splitting this into two orders would have doubled it. This is the kind of logistics thinking the pro tips guide covers for real projects.
Illustrative Budget
At an illustrative $0.70/lb for black Grade 60 bar: 421 lb × $0.70 = $294.70 material; accessories ~$25; delivery ~$75; DIY tying $0 → ≈ $395 total. (Illustrative pricing — the cost guide explains the full budget method.)
What This Example Demonstrates
- The corner correction mattered: outer perimeter (104 ft) vs non-overlapping runs (96 ft) is an 8% swing before a single bar is counted.
- Laps were modest here (12.5 ft, ~4% of longitudinal) because runs were short relative to stick length — on long commercial runs they’d dominate.
- Transverse steel was 14% of total weight — the line item most often forgotten entirely.
- The whole estimate traces to a cut list — every piece above becomes one order line.
Remember: this project is fictional. Its value is the worked procedure — measure non-overlapping runs, count bars, add laps, count transverse steel with the +1, convert to weight, add waste — which is exactly what the calculator automates.
Related Guides
- Estimating Guide — step-by-step measurement and counting workflow.
- Complete Guide — the full guide to foundation rebar estimating.
- Cost Guide — pricing rebar by ton, size, and labor.
- Common Mistakes — the errors to audit your estimate against.
- Formula Explained — the math behind bar counts, laps, and weight.
Run Your Own Numbers
This garage is hypothetical, but your foundation isn’t. Take your actual footing dimensions, bar layout, and spacing to the Foundation Rebar Calculator and run the same seven steps — measure, count, lap, transverse, weigh, waste, check — against real drawings. The procedure scales from a garden shed to a full basement.
Open the Foundation Rebar Calculator
Disclaimer: This case study is a hypothetical illustration with invented dimensions, designs, and prices — not a real project. Calculator results are planning estimates based on the dimensions and layout you enter. Verify quantities with your supplier, have structural designs reviewed by a qualified engineer, and check your local building code before ordering or installing.
