Transcript Section 6.4

BUILDING CONSTRUCTION
STAIRS AND STAIRCASES
Stairs : “It’s a series of steps suitably arranged for the purpose of connecting
different floors of the building.”
 General specification about stairs

Should be locate at centre of building geometry

Should be near to the entrance

Sufficient amount of stairs incase of huge geometry

Location such that ease to reach and at lesser time from any part of
the building

Material used in stairs must be fire resistive and non corrosive
Staircases : “ enclosure of the building in which stair is located”
Technical terms of stairs their specifications:
Technical terms of stairs:
1.
Step: a single unit composed of Rise and Tread
2.
Tread: Upper flat portion of step upon which the foot is placed for ascending or
descending
3.
Riser: vertical portion of step providing support to the tread
4.
Rise: the vertical distance between two successive tread facing
5.
Going: horizontal distance between two successive riser faces
6.
Baluster: vertical member of wood or metal, supporting the hand rail
7.
Balustrade: combine frame work of railing and baluster , used to provide protection to
the user
8.
Hand rail: molded member of wood or metal, used to providing assistance and safeguard
to person while going over stair
9.
Flight: a series of steps without an intermediate platform
10. Landing: flat platform at the top and bottom of the flight , used to change direction and
for taking rest
Technical terms of stairs:
11. Nosing: protecting edge of tread
12. Pitch or slope: An angle which the line of nosing made with floor
13. String: these are the sloping members which support the steps
14. Scotia: A molding provided under the nosing to improve the elevation of the
step, and provide strength to nosing
15. Waist: thickness of structural slab in case of stair made up of R.C.C
16. Newel post: These are principal posts supporting a hand rail, placed at the ends
of flights to connect the ends of strings and hand rail.
17. Head room: minimum clear vertical distance between the tread and over head
structure i.e. ceiling etc.
18. Run: total length of stair in a horizontal plane, including landings
19. Header: horizontal structural member supporting stair strings or landings.
Technical terms of stairs their specifications:
Figure: Flight and Head room of stair
Technical terms of stairs their specifications:
Figure:
Technical terms of stairs their specifications:
Figure: Flight should be divide if its width more than 1.8 m
Requirement of good stairs:
1) Location:
 Sufficient light and ventilation should be available
 Should be Easy to access
 Should be located centrally on building geometry
2) Material: Good quality (Strength, Fire resistance) and should be constructed with good
workmanship
3) Width of Stair: Should be sufficient width and at least 1m in residential building and more
than one meter in case of public building
4) Length of flight: Not more than 12 steps and not less than 3 steps in single flight
5) Pitch of stair: Should not more inclined
6) Head room: should not less than 2 to 2.3m
7) Step Dimension:

Going or tread : should not less than 25cm

Rise: should not more than 15cm

The width of landing should not be less than the width of stair.
Types of Steps in stair:
1. Flier: Ordinary rectangular step
2. Bullnose : Situated at the bottom of flight and having one or both end of step
rounded
3. Round ended: same as bullnose but the top view is semicircular
4. Splayed step: Provided at the beginning step with tapered face
5. Commode Step: Curved riser and tread
6. Dancing step: Horizontally inclined step
7. Winders: Tapering step, usually provided when less space availability, Winders
should be avoid in public building
Types of Steps in stair:
Classification of Stairs
1) Straight stair: Having one single flight or numbers of straight flights
2) Turning stair:

Turning stair further classified as
1.
2.
Quarter turn stair:

Newel Quarter turn

Geometrical quarter
Half turn stair:
•
Dog-legged or Newel Half turn
•
Open newel half turn
•
Geometrical half turn
3.
Three quarter turn stair
4.
Bifurcated stair
5.
Spiral stair
6.
Helical Stair
Types of Stair : Straight Stair
Straight Stair: Plan
Straight between two floors
Continuous in one direction
Single or may be more than one
 Used for Small houses where narrow space is available.
Types of Stair : Newel Quarter Turn Stair
It is used when the direction of flight is changed at right angles to the left or right.
Plan
Sectional Elevation
Newel Quarter Turn Stair
Newel post at the beginning and at the End of each flight
The quarter turn may be of winders or space landing
Types of Stair : Geometrical Quarter Turn Stair
 Commonly provided at the backside of the building for providing entry at various floors.
Plan
Geometrical Quarter Turn Stair
Strings as well as hand rail is continuous
No newel post at the Landing
Having circular shape in plan.
Types of Stair : Dog-Legged Stair Quarter space landing
 It is used when length of staircase is restricted and width is such that only two flight is accommodated
Dog-Legged Stair Quarter space landing: plan
Consists of two Straight flight of steps with abrupt turn between them
 The direction of the flight is turned by 180’
 There is no space between two flights.
Types of Stair : Open Newel Half Turn Stair
Plan
Open Newel Half Turn Stair: plan
 This type of stairs are used at places where sufficient space is available to
accommodate a third flight having three to four steps.
Same as Dog-legged but its having space between two flights.
Types of Stair : Geometrical Half Turn Stair
Geometrical Half Turn Stair: plan
Continuous hand rail without any breakup
May have half space landing or without landing
Types of Stair : Bifurcated Stair
Bifurcated Stair: plan
Common in public building at their entrances hall.
Wide flight at the beginning and narrow flight when it turns in both the direction
Types of Stair : Spiral Stair
Top view circular with single centre of
curvature
Generally made up of R.C.C or Steel
 This type of stairs are used, where space
available is to small and the traffic is less.
Also used as a emergency stairs and provided
at the backside of the building.
Circular Stair: plan
Types of Stair : Helical Stair
 This stair looks very fine.
 The structural design and construction is
very complicated.
 It is made of RCC ,steel and wood.
Helical Stairs: plan
Fabricated Stair :
1. Timber:

Used in residential buildings and at small shops

Light weight

Used when fire resistance criterion not important

Built on place or at shop

Timber used for stair should be free from termite, well treated
2. Metal

Mild steel or cast iron used

Used for factory, godowns, workshops

Not used for residential and public building

They creates noise

Not good appearance
3. Pre-Cast concrete:

Ready made cast available in market
Elevators or Lifts:
“It is the Appliances designed to transport persons or materials between
floors in vertical direction by means of guided vertically movable platform”
 Two basic system :1) Counter weight suspension
2) Electrically motors
Types of Lifts:
1. Passenger lift:

For moving human being
2. Goods lift:

For material transport

Having loading and unloading facilities
3. Hydraulic Elevator or Lift

For Low rise buildings
4. Electric lift

For tall buildings
 Design Criterion/Consideration for Lift

Numbers of lift block, its size, position in building geometry

Particulars of lift block enclosure

Lift door

Number of floors or vertical distance for lift

Height between floor levels

Total headroom

Numbers of entrance

Numbers of passengers to be handled

And of course the weight carrying capacity
 Suitability of Types of Vertical Appliances
GTU- June-2010
1) Dog-legged stair: When need to sudden change of direction while vertical movement of
human Being
2) Elevators or Lift: More than four storey for moving people and materials
3) Ramps: when larger numbers of people or vehicle are to be moved from floor to floor e.g.
Garage, railway station, stadium etc.
4) Escalators: Where traffic is heaviest and convenient for passengers when large numbers of
persons to move from floor to floor,

Generally provided at shopping mall, public building etc for the architectural point of
view

used to guide people towards main exits.

Also speed should be changed based on current of motors.

Inclination angle is 30 degrees.
Ex :- Plan of stair of building in which the vertical distance between the floors is 3.74 m.
The stair hall measures 5.00*2.40 m .
Ans :- 1) take rise 17 cm and tread be 27 cm.
2) Let us keep width of each flight = 1.15 m
3) Width of landing = width of stair = 1.15 m
4) Height of each flight = 3.74/2 = 1.87 m
5) No. of risers required = 1.87/17 = 11 in each flight
6) No. treads in each flight = 11-1 = 10
7) Space occupied in treads = 10*27 = 2.70
8) Space left for passage = 5.0 – 1.50 – 2.70
= 1.15 m ok