stairs design

stair

about the stair

a series of steps or flights of steps for passing from one level to another —often used in plural but singular or plural in construction a narrow private stairs— Lewis Mumford. 2 : a single step of a stairway.

Types of Stairs – Classification of stairs:

Stairs can be broadly classified into three types:

Straight stairs

Turning stairs

Continuous stairs

1. Straight stairs

Generally for small houses, available width is very retractable. So, this type of straight stairs are used in such conditions which runs straight between two floors. This stair may consists of either one single flight or more than one flight with a landing.

2. Turning stairs

Turning stairs are sub classified as:

Quarter turn stairs

Half turn stairs ( dog legged stairs)

Three – quarter turn stairs

Bifurcated stairs

3. Quarter turn stairs

A quarter turn stair is the one which changes its direction either to the right or to the left but where the turn being affected either by introducing a quarter space landing or by providing winders. In these type of stairs the flight of stair turns 90 degrees art landing as it rises to connect two different levels. So it is also called as L-stair. Again these quarter turn stairs are two types.

3.1. Newel quarter turn stairs

These type of stairs have clearly visible newel posts at the beginning of flight as well as at the end. At the quarter turn, there may either be quarter space landing or there may be winders.

3.2. Geometrical quarter turn stairs

In geometrical stairs, the stringer as well as the handrail is continuous without any newel post at the landing area.

4. Half turn stairs

In case of half turn stairs its direction reversed, or changed for 180o. Such stairs are quite common. Again these are three types.

4.1. Dog-legged stairs

Because of its appearance in sectional elevation this name is given. It comes under the category of newel stairs in which newel posts are provided at the beginning and end of each flight.

4.2. Open newel half turn stair

In this type of open newel half turn stairs, stair has a space or well between the outer strings. This is the only aspect in which it differs from the doglegged stair.

4.3. Geometrical half turn stairs

In case of geometrical half turn stairs the stringers and the hand rails are continuous, without any intervening newel post. These stairs may contains either with half space landing or without landing.

5. Three quarter turn stairs

The direction of stairs changed three times with its upper flight crossing the bottom one in the case of three quarter turn stairs. These stairs are may either be newel or open newel type. This type stairs are generally used when the vertical distance between two floors is more and as well as length of the stair room is limited.

6. Bifurcated stairs

Bifurcated stairs are commonly used in public building at their entrance hall. This has a wider flight at the bottom, which bifurcates into two narrower flights, one turning to the left and other to the right, at landing.it may be either of newel type with a newel post or of geometrical type with continuous stringer and hand rails.

7. Continuous stairs

This type of stairs neither have any landing nor any intermediate newel post. They are geometric in shape. These are may be of following types.

Circular stairs

Spiral stairs

Helical stairs

Circular stairs or spiral stairs are usually made either of R.C.C or metal, and is placed at a location where there are space limitations. Sometimes these are also used as emergency stairs, and are provided at the back side of a building. These are not comfortable because of all the steps are winders and provides discomfort.

Design calculation of steps

This question can be basic and you may know the answer, but it's always good to remember some elementary calculations that help us to streamline the design process.

As we know, a staircase consists basically of a series of steps, which in turn consist of a tread (the horizontal part, where the foot will rest) and a riser (the vertical part). Although it can vary in its design, each step must also have one or more landings, handrails, and a small nosing. The latter protrudes from the tread over the lower step, allowing to increase its size without adding centimeters to the overall dimensions of the staircase.

Check the effective formula developed by French architect François Blondel, which allows you to determine the correct dimensions of a comfortable and efficient staircase according to its use.

2 Risers + 1 Tread = 63-65 cm 

The necessary space to reach these optimal dimensions is not always available, but it's recommended to approach them as much as possible.

A schematic example of a steep and low-transit staircase

(2 x 21) + (1 x 21) = 63 cm  

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A schematic example of an optimal staircase

(2 x 18) + (1 x 28) = 64 cm

A schematic example of a loose staircase, preferably for outdoor use

(2 x 13) + (1 x 39) = 65 cm

Sample calculation of a staircase that should be 2.60 meters high 

1. Calculate the number of steps that will be needed

Considering an ideal riser of 18 cm, the height of the space is divided by the height of each step. The result should always be rounded up:

260/18 = 14.44 = 15 steps

2. Calculate the height of each riser

The height of the space is divided by the number of steps that we have just obtained:

260/15 = 17.33 cm height for each riser

3. Calculate the width of the tread

Apply the Blondel formula:

(2 x 17.33 cm) + (1 x tread) = 64 

Each tread will measure 29.34 cm

* The resulting staircase will have 15 steps of 29.34 cm of tread and 17.33 cm of riser

How to determine the width of the stairs?

Depending on the use and local regulations, a minimum width of 80 cm is recommended for stairs in single-family homes, and greater than 1.00 meters in public buildings, taking into consideration the tentative number of people who will use it. As a reference, according to the traditional book 'Architects' Data' by Ernst Neufert, in a staircase of 1.25 meters two people can go up and down at once, and in one of 1.85 meters 3 people can do it at the same time, with one appropriate distance of 55 cm between the person and the handrail.

After how many steps should a landing be included?

Ideally, a stairway shouldn't have more than 15 steps in a row. After 15 steps, a landing should be provided. It's recommended that a landing measure at least the same as 3 treads.