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Calculate the concrete volume needed for stairs and landings. Estimate materials, verify code compliance, and determine costs for your concrete stairway project.
Stairs: (W × R × H × N) / 2 / 46656
Landing: (L × W × T) / 46656
Where W = width, R = run, H = rise, N = steps, L = landing length, T = thickness (all in inches)
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Concrete stairs are a durable and permanent solution for exterior and interior applications. Understanding the key dimensions and terminology is essential for a successful project.
Total Rise: The vertical distance from bottom to top of the stairs.
Total Run: The horizontal distance the stairs cover.
Riser: The vertical height of each individual step.
Tread: The horizontal depth of each step where you place your foot.
The most comfortable stair dimensions follow the rule that two risers plus one tread should equal 24-25 inches (2R + T = 24-25).
Total rise: 84 inches (7 ft)
Target riser: 7 inches
Steps = 84 / 7 = 12 steps
Actual riser = 84 / 12 = 7.0"
If run = 110 inches:
Tread = 110 / 11 = 10.0"
Check: 2(7) + 10 = 24" ✓
Standard residential building code requirements for stairs (IRC R311.7):
| Dimension | Minimum | Maximum | Ideal |
|---|---|---|---|
| Riser Height | 4 inches | 7.75 inches | 7 inches |
| Tread Depth | 10 inches | - | 11 inches |
| Stair Width | 36 inches | - | 42-48 inches |
| Headroom | 80 inches (6'8") | - | 84 inches (7') |
| Landing Depth | 36 inches | - | 48 inches |
Note: Always check with local building codes as requirements may vary by jurisdiction.
The most comfortable ratio follows the formula 2R + T = 24-25 inches. For example, a 7-inch riser with an 11-inch tread (2×7 + 11 = 25) provides optimal comfort and safety.
Yes, all stairs must meet local building codes. Typical requirements include riser heights between 4-7.75 inches, tread depth minimum 10 inches, and width minimum 36 inches. Always check with your local building department before construction.
Build sturdy side stringers with cut-out steps, install riser boards, add rebar reinforcement, apply form release oil, pour concrete from bottom to top, and finish the treads. Forms must be well-braced as concrete is very heavy.
Wait at least 7 days before removing forms and using the stairs. Full strength develops after 28 days. Keep concrete moist during curing for best results.
Yes, setting steel posts in wet concrete provides the strongest attachment. Use flanged posts with the flange embedded in concrete, or set posts 4-6 inches deep. Ensure posts are properly aligned and braced while concrete cures.
Apply a broom finish while concrete is still workable, add grit to the surface before it sets, use stamped texture patterns, or install anti-slip tread strips after curing. Outdoor stairs especially need slip resistance.
Outdoor stairs need deeper footings below frost line, better drainage, slip-resistant finish, and often a shallower slope. Use air-entrained concrete in freeze-thaw climates for better durability.
Most jurisdictions require permits and inspections for concrete stairs, especially exterior stairs or those serving as main access. Inspections typically occur before concrete pour (rebar/forms check) and after completion.
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