Introduction
This case study is a hypothetical, illustrative example — a fictional project constructed to show how the estimating workflow, cost breakdown, and construction sequence from this guide cluster fit together on a realistic small stair. The numbers are worked realistically from the same formulas the Concrete Stair Calculator uses, but no real client, site, or contractor is involved.
The scenario: a homeowner replaces a rotting timber stair between a back patio and a raised porch with poured concrete steps — 7 risers, a small landing, bag-mixed over one weekend. Follow along to see every decision point, from the first tape measurement to the final inspection.
The Project (Hypothetical)
The fictional homeowner — let’s call her the owner — has a porch floor 1.2 m above a patio that will be repoured next year. The existing timber steps are rotting at the stringers. She wants concrete: permanent, low-maintenance, and broom-finished for wet-weather grip. Constraints: the work must pass a residential permit inspection, the patio’s future finished height is known (10 cm above current rough grade), and she has one free weekend plus a borrowed pickup.
Step 1: Measuring and Estimating
Following the estimating guide sequence, she measures the total rise from the porch floor to the planned patio finish: 120 cm. Three measurements across the width agree within 5 mm. The math:
- Riser count: 120 ÷ 18 = 6.67 → 7 risers; actual riser = 120 ÷ 7 = 17.14 cm (6.75 in)
- Tread depth chosen: 28 cm (11 in); the porch slab serves as the top tread, so 6 treads are formed: 6 × 28 = 168 cm (5.51 ft) of run
- Width: 1.2 m (3.94 ft) inside the forms
- Step volume: 7 × 1.2 × 0.28 × 0.1714 ÷ 2 = 0.2016 m³
- Landing at the base: 1.2 × 1.2 × 0.10 = 0.144 m³ (she adds a small landing because the patio won’t exist yet — the stair needs something to land on)
- Footings: two 1.4 × 0.3 × 0.6 m trenches below frost line = 0.504 m³
- Total geometric: 0.2016 + 0.144 + 0.504 = 0.85 m³; with 10% waste = 0.93 m³
She cross-checks in imperial: steps 7.11 ft³ + landing 5.09 ft³ + footings 17.8 ft³ = 30.0 ft³ = 1.11 yd³; metric 0.85 m³ = 1.11 yd³ ✓. Bag count: 0.93 m³ ÷ 0.017 = 54.7 → 55 eighty-pound bags.
Step 2: The Supply Decision
At 55 bags, she’s past the comfortable bag-mix zone (the cost guide puts the crossover near 30 bags). She calls two ready-mix suppliers: both quote ~$160/yd³ plus a $95 short-load fee for her 1.25 yd³ order — about $295 delivered. Fifty-five bags at $6.50 would be $358 plus a $75 mixer rental and a full day of mixing labor. Ready-mix wins on cost and consistency, so she books a morning delivery with a 2-hour unload window.
Lesson: the estimate reframed the project. What started as “a bag-mix weekend” became a ready-mix pour once the landing and footings were honestly included — exactly why extras get estimated separately.
Step 3: Permits and Prep
She submits a simple plan to the building department: stair location, 7 risers at 17.14 cm, 28 cm treads, 1.2 m width, 60 cm footing depth (local frost line: 45 cm), #4 dowels into the porch foundation, handrail on one side at 90 cm. Permit issued in a week. She excavates the footing trenches, compacts 12 cm of crushed stone in lifts, sets rebar on chairs, drills and epoxies dowels into the foundation, and passes the footing inspection on Friday morning — the pour is booked for Saturday.
Material spend (illustrative, typical US ranges): ready-mix $295, formwork lumber and plywood $110, rebar/dowels/tie wire $55, crushed stone $45, release agent and misc $30 — about $535 total, plus the permit fee.
Step 4: Forming and Pour Day
Saturday 7 a.m.: riser boards screwed to plywood cheek forms, staked every 50 cm with diagonal kickers, release agent applied, chamfer strips on the step edges, nosing setback of 2.5 cm marked on the side forms. Using the pour-day checklist, she verifies every item before the truck arrives at 9.
The pour follows the pro tips sequence: bottom step first, each tread filled to its riser board, spade worked along every riser face to prevent honeycombing, each tread screeded level before moving up. The landing and footings were poured first (they were inspected Friday). By 11:30 the truck is washed out; by early afternoon the treads are broom-finished after the bleed water leaves, control joints are tooled at the stair-to-landing junction, and the whole stair is covered in wet burlap under polyethylene.
Step 5: Curing and Inspection
She keeps the burlap wet for 7 days — the single highest-return effort in the project. Forms are stripped on day 3 (carefully, after the concrete has gained handling strength), revealing crisp chamfered edges with no honeycombing. On day 10, the handrail goes up: posts epoxy-anchored into sleeves she had the foresight to set during forming. The final inspection passes on the first visit: risers uniform at 17.1–17.2 cm, treads at 28 cm, rail at 90 cm, landing 1.2 × 1.2 m.
What Made It Work (and What Nearly Didn’t)
- Measuring to the planned patio height — not current grade — kept every riser uniform. This was the decision the whole project hinged on.
- Estimating the extras separately revealed the true 0.93 m³ scope and flipped the supply decision from bags to ready-mix, saving money and improving quality.
- The Friday footing inspection caught one trench 5 cm shallow — fixed in twenty minutes with a shovel, versus a failed pour.
- Near-miss: she almost skipped the release agent on “just the cheek forms.” The checklist caught it. Stripping would have been destructive without it.
- Near-miss: the truck arrived 40 minutes early while she was still setting the last kicker. Because materials were staged the night before, the delay cost nothing — a reminder that staging is part of the estimate’s logistics, not an afterthought.
Final Numbers (Illustrative)
| Item | Planned | Actual |
|---|---|---|
| Concrete volume ordered | 0.93 m³ (1.25 yd³) | 1.25 yd³ delivered; ~0.05 yd³ returned as washout buffer |
| Material cost | ~$535 | ~$560 (extra burlap + second tube of release agent) |
| Timeline | Permit 1 wk; prep Fri; pour Sat | As planned; inspection passed first visit |
| Waste used | 10% allowance | ~7% actual — forms were tight |
Related Guides
- Concrete Stair Complete Guide — the estimating walkthrough used in Step 1.
- Estimating Guide — the measuring sequence the project followed.
- Cost Guide — the bags-vs-ready-mix math from Step 2.
- Pro Tips — the pour-day techniques from Step 4.
- DIY vs Pro — how to decide if your project fits this profile.
- Pour-Day Checklist — the verification list that caught two near-misses.
Frequently Asked Questions
Is this case study based on a real project?
No. It is a hypothetical, illustrative example constructed to demonstrate the estimating workflow, cost logic, and construction sequence. The arithmetic is realistic and follows the same formulas as the calculator, but the people, site, and events are fictional.
How long did the hypothetical project take?
About a week for the permit, one day of prep and footing inspection, one pour day, and 7 days of curing — with the final inspection roughly two weeks after the pour. Real timelines vary with permit offices and weather.
Why did the example switch from bags to ready-mix?
Honestly estimating the extras (landing + footings) raised the total to 0.93 m³ — about 55 bags — past the ~30-bag crossover where ready-mix becomes cheaper and more consistent. The step volume alone (14 bags) would have been a bag pour.
What was the total illustrative cost?
About $560 in materials plus the permit fee, for a 7-riser stair with landing and frost-depth footings. Costs vary widely by region; see the cost guide for the pricing logic.
What nearly went wrong?
Two near-misses: almost skipping release agent on the cheek forms (caught by the checklist), and the truck arriving 40 minutes early (absorbed because materials were staged the night before).
Can I copy this project’s numbers for my stair?
Use the method, not the numbers. Your total rise, frost depth, and code requirements will differ. Run your own dimensions through the calculator and work the same sequence.
Get Your Number
Hypothetical or not, the workflow is the real takeaway: measure finished-to-finished, derive the riser count by rounding up, estimate every extra as its own shape, let the honest total choose your supply method, and verify everything twice — once on paper, once on site. Run your dimensions through the Concrete Stair Calculator and start your own version of Step 1.
Disclaimer: Calculator results are planning estimates based on the dimensions you enter. Actual concrete requirements vary with site conditions, formwork accuracy, and mix design. Verify volumes with your supplier and consult a licensed professional or your local building authority for structural or code-related decisions.
