Staircase is one of
the essential parts of a building. It helps people to access different floors
in a building. In this article, I will explain how to estimate concrete volume
and quantity of cement, sand, aggregates for a staircase. Before starting the estimation,
we need to know different components of a staircase which I will use in this
calculation.
COMPONENTS OF STAIRCASE:
STEPS:
A
portion of stairway comprising the tread and riser which permits ascent and
descent from one floor to another.
TREAD:
The horizontal
upper part of a step on which foot is placed in ascending or descending
stairway.
RISER
The vertical
portion of a step providing support to the tread.
FLIGHT
A series of steps
without any platform, break or landing in their direction.
LANDING:
A platform or
resting place provided between two flights.
Now coming to the
calculation of concrete volume for the staircase.
Let’s take an
example:
The height of one
floor = 12 feet.
Height to be
acquired by one flight = 12/2 = 6 feet.
Risers = 6″ = 0.5
feet.
Number of risers =
Height of flight / Riser = 6/0.5 = 12
Tread = 10″ = 0.8
feet.
Number of treads =
(Numbers of risers -1) = 12 – 1
Thickness of waist
slab = 6″ = 0.5 feet
Length of step = 5
feet
VOLUME OF CONCRETE FOR STEPS:
Volume of one step
= 1/2 x riser x tread x length of step
= 1/2 x 0.5 x 0.8 x
5 = 1.03 = 1 cubic feet.
As we have 11
number of steps in a flight the volume of steps for first flight = 11 x 1
= 11 cubic feet.
CONCRETE VOLUME FOR WAIST SLAB:
To calculate the
volume of concrete for waist slab we need to know the inclined length of the
waist slab.
Horizontal length
of waist slab = Tread x Number of steps
=0.8333′ x 11 = 9.2
feet.
The height of the
top of the landing from floor = Number of riser x Height of riser
= 12 x 0.5 = 6
feet.
The volume of
concrete for waist slab = Inclined length of waist slab x Width of waist slab x
Thickness of waist slab
= 11′ x 5′ x 0.5′
= 27.5 cubic feet
∴ Volume of concrete for first flight = Volume of
waist slab + Volume of steps
= 27.5+11 = 38.5
cubic feet
VOLUME OF CONCRETE FOR LANDING OF STAIRCASE:
Length of landing =
10.5 feet
Width of landing =
5 feet
Thickness of
landing = 0.5 feet
∴ Concrete volume for landing = 10.5′ x 5′ x 0.5′
= 26 cubic feet.
CONCRETE VOLUME FOR 2ND FLIGHT OF THE STAIRCASE:
As the 1st light and 2nd flight are same in
our staircase so the volume of concrete will be same.
Concrete volume for 2nd flight of the
staircase = 38.5 cubic feet.
∴ Total volume of concrete for staircase =
Volume of first flight + Volume of second flight + Volume of landing
= 38.5 + 38.5 + 26
= 103 cubic feet.
Well, this is the wet volume of concrete. To
convert wet volume into dry volume we need to multiply with 1.54
∴ Dry volume of concrete = 103 x 1.54 = 159 cubic feet.
QUANTITY OF MATERIALS FOR STAIRCASE:
We will calculate for 1:2:4 Concrete mix.
1. Volume of cement = 1/7 x Dry volume = 1/7
x 159 = 22.66 cubic feet.
∴ Number of Cement bags = volume of
cement / Volume of cement bag = 22.66 / 1.25 = 18 No’s of bag. (The
volume of one bag cement of 50 kg = 1.25 cubic feet)
2. Volume of Sand = 2/7 x Dry volume = 2/7
x 159 = 45 cubic feet.
3. Volume of Aggregate = 4/7 x Dry volume =
4/7 x 159 = 91 cubic feet.
Note: Here I have used cubic feet unit and 1:2:4 mix ratio, you
can use cubic meter unit and any other mix ratio of concrete.
