{"id":30288,"date":"2023-11-23T12:40:04","date_gmt":"2023-11-23T11:40:04","guid":{"rendered":"https:\/\/biblus.accasoftware.com\/en\/?p=30288"},"modified":"2024-12-18T14:14:55","modified_gmt":"2024-12-18T13:14:55","slug":"how-to-calculate-stair-steps","status":"publish","type":"post","link":"https:\/\/biblus.accasoftware.com\/en\/how-to-calculate-stair-steps\/","title":{"rendered":"How to Calculate Stair Steps"},"content":{"rendered":"

From the Blondel rule to using BIM software: here’s how to calculate stair steps for user comfort and safety<\/p>\n

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Internal stairs serve as vertical connections between different levels in a building, whether it’s a mezzanine, an upper, or lower floor. Designing stairs requires a precise evaluation of measurements, considering the height difference to overcome and consequently, the number of steps and the plan layout. One crucial aspect in creating a staircase is the optimal calculation of the rise and tread, essential elements to ensure comfort and safety during use. Incorrect ratios between the rise and tread are serious trip and fall hazards. Let’s explore all the rules to correctly calculate stair steps and how the use of 3D building design software<\/a> can be immensely supportive.<\/p>\n

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Determining the rise\/tread ratio: the Blondel Rule<\/h2>\n

In the field of staircase design, one of the key concepts is the ratio between the rise (height of the step) and the tread (depth of the step). One of the most known formulas is the “Blondel rule<\/em>,” which states:<\/p>\n

2a+p=62\/65 cm<\/em><\/p>\n

where a<\/em> represents the height of the rise, and p<\/em> represents the length of the tread.<\/p>\n

This ratio is commonly used; however, it has evident limitations, especially on low step heights. For minimal heights, the result is unsatisfactory, and in fact, the toe tends to hit against the rise.<\/p>\n

Beyond the Blondel Rule: Andr\u00e9 Hermant’s Proposal<\/h2>\n

Architect Andr\u00e9 Hermant introduced another perspective in determining step proportions, considering the movement during stair ascent. Hermant formulated a ratio based on walking speed and step length at different speeds, emphasizing that the speed remains constant even with different inclinations. The formula proposed by Hermant:<\/p>\n

h*p=600<\/em><\/p>\n

where h<\/em> represents height and p<\/em> the step, leads to different proportions compared to the Blondel rule but can be adapted to various conditions.<\/p>\n

Other calculation proposals<\/h2>\n

Many other scholars have ventured into formulas and rules to achieve the right proportion between rise and tread, such as Sacchi, Bosco, Colombo, and other English authors like Warth.<\/p>\n

Here’s a table below that, given the rise value, expresses the tread value according to different theories.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n
RISE<\/strong><\/td>\nTREAD – SACCHI<\/em><\/strong><\/td>\nTREAD – BOSCO<\/em><\/strong><\/td>\nTREAD – WARTH<\/em><\/strong><\/td>\n<\/tr>\n
12<\/strong><\/td>\n38<\/td>\n34<\/td>\n36<\/td>\n<\/tr>\n
13<\/strong><\/td>\n36<\/td>\n33<\/td>\n34,7<\/td>\n<\/tr>\n
14<\/strong><\/td>\n34<\/td>\n32<\/td>\n34,7<\/td>\n<\/tr>\n
15<\/strong><\/td>\n32<\/td>\n31<\/td>\n32<\/td>\n<\/tr>\n
16<\/strong><\/td>\n30<\/td>\n30<\/td>\n30,7<\/td>\n<\/tr>\n
17<\/strong><\/td>\n28<\/td>\n29<\/td>\n29,4<\/td>\n<\/tr>\n
18<\/strong><\/td>\n26<\/td>\n28<\/td>\n28<\/td>\n<\/tr>\n
19<\/strong><\/td>\n24<\/td>\n27<\/td>\n26,7<\/td>\n<\/tr>\n
20<\/strong><\/td>\n22<\/td>\n26<\/td>\n25,4<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n

Based on experience, for an internal staircase, it’s recommended to adhere to the following values:<\/p>\n