How to Calculate Staircase Shuttering


The article explains the shuttering calculation and the staging for a staircase with an example. The article is detailed to develop the concepts of shuttering and staging calculation.

Before going into the calculations, let us understand the terminology of staircase used in this article.

Staircase Terminology

Flight

The portion of a staircase that takes us to different levels. It has continuous steps. A flight connects two landings.

Waist Slab

The bottom portion of the flight that supports the steps. The thickness is 150-200 mm.

Tread

The part of the step on which we keep our feet. It is the top portion of the step. The ideal width of a tread is such that it can accommodate all the feet sizes. The general tread size is 250-300 mm.

Riser

A riser gives the height to each step. It is the rising part of the step. Or in other words, the riser is the vertical distance between two treads. The general size of the riser is 150-200 mm.

Landing

The horizontal part of the staircase on which a flight starts or ends. It is the resting place. Landings are used to change the direction of the stairs.

Horizontal Projection

The plan area of the waist slab of the staircase is called horizontal projection. It is also called “going of flight”. It is equal to the horizontal distance between the first and last riser.

Plan and Elevation of a Staircase Flight

Data Observed From Drawing

The drawing shows the plan and elevation for a flight of a staircase that extends from +4.2 m to +6.3 m.

Considering the above drawing, the following data can be inferred. Bottom level of flight = +4.200 m

Top-level of flight = +6.300 m

Therefore, height of flight = (Top level of flight – bottom level of flight)

= 6.3 -4.2 = 2.1 m Tread = 250 mm = 0.25 m

Riser = 175 mm = 0.175 m

Waist Slab thickness = 150 mm = 0.15 m

Width of waist slab = 900 mm = 0.9 m

Width of landings = 900 + 100 + 900 = 1900 mm = 1.9 m

Landing length at +4.2 m level = 1200 mm = 1.2 m

Landing length at +6.3 m level = 1050 mm = 1.05 m

Horizontal Projection of Waist Slab = (No. of treads x tread width)

= 11 x 0.25 = 2.75 m

Calculation

The calculation for shuttering of various elements of a staircase are as follows-

Waist slab

Length of waist slab = √((Height)2 + (Horizontal Projection)2)

= √((2.1)2 + (2.75)2) = 3.46 m

The waist slab has side shuttering on two sides and centering at the bottom.

Side Shuttering

= (Length of Waist Slab x Thickness)

= 3.46 x 0.15 = 0.52 m2 ……a

Bottom Centering

= (Length of slab x Width of slab)

= 3.46 x 0.9 m = 2.11 m2 ……b

Total waist slab shuttering = a + b

= 0.52 + 2.11 = 2.63 m2

Landing slab at +4.2 m

The landing slab has side shuttering at three sides.

Side Shuttering between column B1 & B1′ (along y-axis) = (Landing width x Landing thickness)

= 1.9 x 0.15 = 0.285 m2 ……c

Two numbers side shuttering along the landing length (along x-axis)

= (No. of Sides x Landing length x Landing thickness)

= 2 x 1.2 x 0.15 = 0.36 m2 ……d

Bottom centering for landing

= (Landing length x Landing width)

= 1.2 x 1.9 = 2.28 m2 ……e

Total shuttering for landing:

= c + d + e

= 0.285 + 0.36 + 2.28 = 2.925 m2

Landing slab at +6.3 m:

The landing slab has side shuttering at three sides.

Side Shuttering between column A1 & A1′ (along y-axis) = (Landing width x Landing thickness)

= 1.9 x 0.15 = 0.285 m2 ……f

Two numbers side shuttering along the landing length (along x-axis) = (No. of Sides x Landing length x Landing thickness)

= 2 x 1.05 x 0.15 = 0.315 m2 ……g

Bottom centering for landing = (Landing length x Landing width)

= 1.05 x 1.9 = 1.995 m2 ……h

Total shuttering for landing

= f + g + h

Treads = 0.285 + 0.315 + 1.995 = 2.595 m2

Tread sides are triangular in shape; therefore, the side shuttering is triangular and on both sides.

= 2 x {(1/2) x Tread x Riser}

= 2 x {(1/2) x 0.250 x 0.175} = 0.044 m2

Total tread side shuttering = (No. of treads x side shuttering for one tread)

Riser = 11 x 0.044 = 0.48 m2

A riser rests on the waist slab and has shuttering on the front side only, and the top is open for concrete pouring.

Shuttering for 1 Riser = (Riser x Width of flight)

= 0.175 x 0.9 = 0.1575 m2

Total riser shuttering = (No. of risers x Shuttering for 1 riser)

= 12 x 0.1575 = 1.89 m2

Total Shuttering for all elements of the flight

= (Waist Slab + Landings + Treads + Risers)

= 2.63 + 2.925 + 2.595 + 0.48 + 1.89 = 10.52 m2

Staging

The staging is the temporary arrangement to support the centering. It is an essential part of the shuttering system. Let us calculate it.

Staging = (Staircase Plan Area x Height of Staging) Plan Area of Landing at +4.2 m level-

 = (Landing width x Landing thickness)

= 1.9 x 0.15 = 0.285 m2 ……i

Plan Area of Landing at +6.2 m level-

= (Landing length x Landing width)

= 1.05 x 1.9 = 1.995 m2 ……j

Plan Area of Flight-

= (Flight Length x Flight Width)

= 2.75 x 0.9 = 2.475 m2 ……k

Staircase Plan Area:

= (i + j + k)

= 0.285 + 1.995 + 2.475 = 4.755 m2             ……l

Height of Staging:

The staging is set on the previous flight, which rises from 0 m to +2.1 m levels. Therefore, the height of the staging is 2.1 m.

Staging:

= 4.755 x 2.1 = 9.99 m2

Say, = 10 m2


Also Read –

How To Calculate Concrete For Staircase

How To Calculate Slope For Staircase

How To Calculate Land Area Or Plot Area


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