Staircase Design | Calculation of Tread, Riser and Landing in Staircase

The staircase is the vertical means of movement. Staircases are the main parts of the buildings and are the weakest part of the building. Staircase Design plays a vital role during the construction of the building.

A staircase may be defined as one or more flights of stairs that help to reach from one floor to another and contains landings, newel posts, handrails, balustrades, and additional parts.

A stairwell is a section increasing vertically through a building in which stairs are placed. The design of staircase can help to improve the beauty of the building as well as improves in strength and durability of the Building.

  1. Parts of a Staircase  

The parts of a staircase can vary depending on the type of staircase. Following are the various parts of a staircase for different types of stairs:

2.1. Step  

The step is made of a combination of tread and riser in the staircase.

2.2. Tread

Tread part of the stairway in which we stepped. It is made to a similar thickness as any other type of flooring. The tread is known from the outer end of the step to the riser between steps. The “width” is known from one side to the other.

Material

The material used to prepare the tread can be timber, steel, glass, acrylic, panel product, or tiling.

Shape and Size

In standard stairs in a residence, the minimum depth/tread is 10 inches.

2.3. Riser

The riser is vertical parts between each tread on the stair. This may be seen as an “open” stair effect.

Material

It is a vertical portion where the material used can be timber, steel, glass, acrylic, and panel production tiling.

Shape and Size

The stair riser heights should be 7 inches (178mm) maximum and 4 inches (102mm) minimum. The height should always be measured vertically between the nosings of adjacent treads. The greatest riser height within any flight of stairs should not be more than the smallest by more than 3/8 and the rise should not be small than 11 inches.

2.4. Nosing

An end portion of the tread sticks out over the riser below. If it is available, it this known that measured horizontally, the total “run” length of the stairs is not simply the sum of the tread lengths, as the treads overlap each other little.

Material

These portions can be prepared from various types of materials which can be Aluminum, vinyl, and wood.

2.5. Starting step or Bullnose

In the staircase where stairs are open on one or both sides, the first step up the lower floor might be wider than the other steps and rounded. The balusters form a semicircle near the circumference of the rounded part.

The handrail contains a horizontal spiral called a “volute” that helps the top of the balusters. The starting steps permit the balusters to form a wider, more stable base for the end of the handrail.

Handrails that end at a post at the foot of the stairs can be low and sturdy, even with a thick post. A double bullnose can be utilized when both sides of the stairs are open.

2.6. Stringer

The structural member that helps the treads and risers. There are two stringers, one on either side of the stairs; though the treads may be carried on many other ways.

The stringers are notched so that the risers and treads adjust into them. Stringers on open-sided stairs generally open themselves so that the treads can be seen from the side.

This type of stringers is called “cut” stringers. Stringers on a closed side of the stairs are closed, with the help of the treads routed into the stringer.

Shape and Size

Many important types of string are usually 220mm wide and 32mm thick. The length will turn on the rise and go.

2.7. Winders

Winders are steps that are small on one side than the other side. They are utilized to vary the direction of the stairs without landings. Several winders form a circular or spiral stairway.

When 3 steps are utilized to rotate a 90° corner, the middle step is known as a kite winder as a kite-shaped quadrilateral.

Shape and Size

The winders should be in a room with the required calculation. You cannot construct winders in an area made of only 2 corner walls. If it is required, surround the area with invisible walls so that a room area is given.

2.8. Trim

Trim is used where walls meet floors and generally below treads to conceal the tell where the tread and riser meet. Shoe molding may be utilized between where the lower floor and the first riser meet.

Trimming is a beginning process that is a new challenge as the last riser above the lower floor is rounded.

Flexible, plastic trim is available for this purpose, however, wooden moldings are still used and are either cut from a single piece of rounded wood or bent with laminations Scotia is a concave molding that is underneath the nosing between the riser and the tread above it.

2.9. Fillet

A garnishing filler piece on the floor between balusters on a balcony railing.

2.10. Banister, Railing or Handrail

The angled member for handholding is well known for the vertical balusters which support it stairs that are open on one side.

There is generally a railing on both sides, only on one side or not at all, on wide staircases, there is also one in the middle, or can even be more.

The term “banister” is utilized to explain the handrail, or the handrail and the balusters, or just the balusters.

2.11. Volute

A handrail end part for the bullnose step curves inside like a spiral. A volute is explained to be right or left-handed varying on which side of the stairs the handrail is as one faces up the stairs.

2.12. Turnout

The alternative of a full spiral volute, a turnout is a quarter-turn rounded edge to the handrail.

2.13. Gooseneck

The vertical handrail that meets a sloped handrail to an upper handrail on the balcony or landing is a gooseneck.

2.14. Rosette

The place where the handrail finishes in the wall and a half-newel is not utilized, it may be crop by a rosette.

2.15. Easings  

The wall handrails go up directly onto the wall with wall brackets. At the bottom of the stairs, such railings become wider to a horizontal railing and this horizontal part is called a “starting easing”. At the top of the stairs, the horizontal portion of the railing is called an “over easing”.

2.16. Core rail  

The wood handrails generally contain a metal core to give extra strength and stiffness, mostly when the rail is to be curved against the grain of the wood. The archaic reference for the metal core is “core rail”.

2.17. Newel

A large baluster or post is used to anchor the handrail. Since it is a structural element, it longs beneath the floor and subfloor to the lower part of the floor joists and is bolted right to the floor joist.

A half-newel can also be utilized where a railing finishes in the wall. It looks like half the newel is added to the wall. For open landings, a newel can be increased below the landing for a garnishing newel drop.

2.18. Finial

A garnishing cap to the top of a newel post, particularly at the end of the balustrade.

2.19. Base Rail or Shoe Rail

The place where the baluster does not begin at the treads, they go to a base rail. This permits for identical balusters, neglecting the second baluster problem.

  2. Staircase Design Formulas  

Before entering the design of the staircase, there are several criteria or you can formulas that should be known.

a. Relation Between Riser and Tread

b. Standard Values:

The design of the staircase should build it within the limit of government policies. So, always be aware while assuming the value of tread and riser.

a. For Residential Building: T= (220 – 270) mm, R= (150 – 170) mm

b. For Public Building: T= (250-300) mm, R= (100-150) mm

c. Usual Sizes of steps

a. For Residential Building: (150 x 270) mm to (170 x 220)mm

b. For Public Building: (100 x 300) mm to (150 x 250) mm

d. Types of Staircases:

a. Public Building = Open well staircase

b. Residential Building = Dog-legged Staircase

Where,

NT= Number of Tread

T = Size of Tread

L= Landing

E= Entry Space

Where,

NR = Number of Riser

  3. Numericals of Staircase Design  

1. Draw a plan of a dog-legged staircase for a building in which the vertical distance between floors is 3.6 m. The stair hall measures 2.5 m x 5m.

Given,

Floor Height = 3600 mm

Types of staircase = Dog Legged staircase

Assume,

Riser (R)= 150 mm

Number of risers (NR) = 3600 / 150 = 24 nos

Number of Riser in One Flight = 24/2 = 12 nos

Number of Tread in one Flight = 12-1 = 11 nos

Now,

T+2R = 600

T + 2×150= 600

T= 600-300

T= 300 mm

Size of tread = 300 mm

Width of stair = 1200 mm

Size of Landing = Width of stair = 1200 mm

Entry Space(E) = 5000-1200-11×300 = 500 mm

Here, is our design of staircase.

2. Design a proper layout of an RCC Stair for a hospital that consists of the ground floor and first floor from the following data.

Inside Dimensions of staircase = 6m x 4.5 m

Height of each floor = 3.75 m

The thickness of the floor slab= 150 mm

Height of stair cabin = 2.50 m

Width of stair= 1.5 m

Solution,

Total Floor Height = 3750+150 = 3900 mm

Types of Staircase = Open well Staircase

Assume,

Riser (R) = 150 mm

Total Number of riser = 3900/150 = 26 nos

Now,

T+2R= 600

T= 600- 2×150

T= 300 mm

Also, width of stair = 1500 mm

Landing of stair = 1500 mm

Here provide 9 treads in the First Flight, 5 treads in the second flight, and 9 treads in the third flight.

Entry Space (E) = 6000-1500-9×300 =1800 mm

Here, is our design of staircase.