Stair Calculator: Design and Execution

Calculate exact stair measurements: tread, riser, slope and materials. Apply Blondel's law and avoid construction errors.

Riser -- cm
Tread -- cm
Slope -- º
Actual Run -- cm

Layout and Execution

Step Concrete Height (cm) Finished Height (cm) Run (cm)

Material Estimate

Total Concrete:
0.00 m³
Cement (bags/25kg): 0
Sand Required: 0 L
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Frequently Asked Questions

What is Blondel's law?

It is a formula that establishes that for a staircase to be comfortable, the sum of two risers and one tread should be between 62 and 64 cm (2R + T = 63). This law is based on average human step length and ensures that climbing or descending is safe and comfortable.

What is the maximum height of a step?

In residential buildings, 18-19 cm is recommended. For public spaces, the maximum is typically 17.5 cm according to standards. Higher risers are tiring and potentially dangerous, especially for children and elderly people.

How do I calculate if space is limited?

If horizontal space is limited, you must increase the number of steps (reducing riser height) or accept a steeper slope, though less comfortable. The calculator helps you find the optimal balance.

What does concrete volume calculation include?

The total concrete volume is calculated considering the steps plus the inclined slab (the sloped plane supporting the steps). Ignoring this volume would result in insufficient concrete orders.

Why is cumulative layout important?

Measuring each step separately generates cumulative errors. Cumulative layout ensures all steps have exactly the same height, avoiding hazards and improving usage comfort.

# Staircase Design Geometry: Blondel's Law

The comfort of a staircase depends on human step length. When you climb or descend stairs, your body expects a predictable rhythm. Blondel's law establishes that 2 risers + 1 tread = 62-64 cm is the standard ensuring maximum comfort and safety.

# Structural Control and Materials

For professional execution, it is vital to account for the concrete slab (the inclined plane supporting the steps). Ignoring this volume would result in insufficient concrete orders and defective construction. The calculator automatically integrates this calculation.

# Layout and Marking: Cumulative Error

In construction, the greatest enemy is millimetre-level error. If you measure each step separately, the sum of small errors can leave the last step 5 cm higher or lower than the first. Cumulative layout prevents this problem.

# Final Finish Provisions

A critical detail: are you installing 3 cm granite steps? This data is fundamental. If not properly accounted for, the first step will be 3 cm higher and the last 3 cm lower, creating a real safety hazard.

Bibliographic References

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