:Considerations for stair-Design ...

1. STAIRSSTAIRS
Topic: Considerations for stair DesignTopic: Considerations for stair Design
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2. Stair Design Criteria
(Essential requirements to design a comfortable staircase)(Essential requirements to design a comfortable staircase)
1. FORM AND CONSTRUCTION: -use of the building/ user specific
i trequirements
2. LOCATION WITHIN A BUILDING
3. PITCH
4. TREADS AND RISERS
5. WIDTH OF THE STAIRS
6 MATERIALS AND WORKMANSHIP6. MATERIALS AND WORKMANSHIP
7. HEADROOM
8. FLIGHT
9. SINGLE STEP
10.WINDERS
11.HANDRAILS
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3. STAIRS: INTODUCTION AND BASIC TERMINOLOGIES:
• STAIR:
– Defined as set/series of steps leading from one level to another level, provided to
afford the means of ascent and descent between various floors of a building,
I e element of a building that allows the vertical circulation– I.e. element of a building that allows the vertical circulation.
• STAIR-CASE:
– The room or the enclosure of the building, in which the stair is located is known
as stair-case.as s a case
• STAIR-WAY:
– The opening or space occupied by the stair is known as stair-way.
• GENERAL CONSIDERATIONS:
– Location within the building: Easily accessible to all the users
(Depends upon the use of the building)
– Material: Economical, Functional, Maintenance-free
– Traffic Load
– Fire safety
S i– Service
– Design Considerations as Architectural element
• OTHER MEANS OF VERTICAL TRANSPORTATION:• OTHER MEANS OF VERTICAL TRANSPORTATION:
– Ramps, Lifts, Escalators, Ladders.

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5. TECHNICAL TERMS:
1 STEP:1. STEP:
• It is a portion of stair which permits ascent and descent. It is comprised of a
tread and a riser. A stair is composed of a set of steps.
• Steps in a stair may be of different types, can be designed according toy y g g
requirement.
• Dimensions of a step is very important for comfortable use i.e. the riser and
tread should be well proportioned.
THUMB RULES FOR STEP DIMENSION:THUMB RULES FOR STEP DIMENSION:
– (2xRise in cm) + (Going in cm) = 60
– (Rise in cm) + (Going in cm) = 40 to 45
– (Rise in cm) x (Going in cm) = 400 to 450(Rise in cm) x (Going in cm) = 400 to 450
– Adopt Rise = 14 cm and Going = 30 cm as standard, then for every
combination add 1 cm to the rise and subtract 2 cm for going.
Thus other combinations for rise and going would be,g g
15 cm x 28 cm
16 cm x 26 cm
17 cm x 24 cm
2. TREAD
• It is the upper horizontal portion of a step upon which the foot is placed
while ascending or descending.
3 RISER3. RISER
• It is the vertical portion of a step providing support to the tread.

6. 4. RISE
Vertical distance between two successive tread faces.
5. GOING
Horizontal distance between two successive riser faces.
6. FLIGHT
Unbroken series of steps between landings.
7. LANDING
It is the level platform at the top or bottom of a flight between floors. A
landing facilitates change of direction and provides an opportunity for taking
rest during the use of the stairsrest during the use of the stairs.
8. SOFFIT
The underside of a stair.

7. 8. NOSING
It is the projecting part of the tread beyond the face of the riser. Provided for
architectural purpose as well as to protect the edge of the step from breaking
d dditi l f t tand additional comfort to user.
9. SCOTIA
A moulding provided under the nosing to improve the elevation of the stepA moulding provided under the nosing to improve the elevation of the step
and to provide strength to nosing
11.LINE OF NOSINGS11.LINE OF NOSINGS
It is an imaginary line parallel to the strings and tangential to the nosing. It is
useful in the construction of handrails, giving the line with which the under-
surface of the hand-rail should coincide.
12.PITCH OR SLOPE
It is the angle witch the line of nosing of the stair makes with the horizontal.
13.STRINGS/STRINGERS
The inclined member of a stair which supports the ends of steps is known as
a stringa string

8. 14. NEWEL POST
• Newel post is a vertical member which is placed at the ends of flights to
connect the ends of stings and handrail.
15. BALUSTER
• It is the vertical member of wood, metal, stone or any other suitable
material fixed on step which supports the handrailmaterial, fixed on step, which supports the handrail.
16. BALUSTRADE
• It consists of a row of balusters surmounted by a handrail to provide• It consists of a row of balusters surmounted by a handrail, to provide
protection for the users of the stairs.
17. HAND RAIL
• It is a rounded or moulded member of wood or metal following generally the
contour of the nosing line, and fixed on the top of balusters.

9. 18. HEAD ROOM
• It is the minimum clear vertical distance between the tread and overhead
structure.
•
19. RUN
• It is the total length of stairs in a horizontal plane, including landings.
20. HEADER
• It is the horizontal structural member supporting stair stringers or landings.
21. WALKING LINE
• The approximate line of movement of people on a stair during ascending or
descending is known as a walking line and it is situated at a distance ofdescending is known as a walking line and it is situated at a distance of
about 450 mm from the centre of handrail.

12. Design Criteria / Essential Requirements Of A Comfortable Staircase
WIDTH
Th idth f th t i h ld b ffi i t f t t it- The width of the stair should be sufficient for two persons to pass on it
simultaneously and for furniture and other things to be carried up and down
the stair.
- The minimum width of the stair should not be less than 80cm. in any
case.
- For residential buildings width should be at least 90 cm
- For public building should be between 1.5 m to 1.8 m
If th idth i th 1 8 t l h d il h ld b id d- If the width is more than 1.8m, central handrail should be provided.
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13. Design Criteria / Essential Requirements Of A Comfortable Staircase
• DESIGN OF LAYOUT
Th h i ht f th fl i ll k Th d f d t i i• The height of the floor is generally known. The procedure for determining
the number of treads and risers is as follow:
• The positions of first and last risers are determined with regard to the
positions of doors, windows and internal circulation area.
• A convenient height of the riser is assumed.
• Number of risers = Total floor height• Number of risers = Total floor height
Height of riser
• Number of treads in a flight= number of risers-1
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14. Design Criteria / Essential Requirements Of A Comfortable Staircase
HEADROOM
Provision of headroom is must. Should preferably be not less than 2m.
FLIGHT
• It is not desirable to provide a flight with more than 12 steps or at the
most 15 steps and not less than 3 steps.
• Suitable landings should be provided for user’s comforts. TheSuitable landings should be provided for user s comforts. The
placement of a landing after a certain number of steps is regulated by
statutory instruments and serves to guarantee improved safety.
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15. Design Criteria / Essential Requirements Of A Comfortable Staircase
9. SINGLE STEP
Should be avoided as it is a discomfort in circulation.
10.WINDERS
Should be avoided. If at all required should be designed properly
11.HANDRAILS
When a flight consists of more than three steps should be provided withWhen a flight consists of more than three steps, should be provided with
handrail. If the width of the stair is more, should be provided at both ends. In
public buildings for wider steps should be provided in the centre also. The
height of the handrail should not be less than 80 cmheight of the handrail should not be less than 80 cm
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16. TYPES OF STAIRCASESS O S C S S
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17. SPECIAL TYPES OF STEPS
Sometimes to emphasise the beginning of climbing first two or three steps of theSometimes to emphasise the beginning of climbing, first two or three steps of the
flight are designed differently, with little higher dimension and are detailed out
specially. These steps can be classified as following:
1. BULL NOSE STEP:
Generally provided at the
bottom of flight. It projectsg p j
in front of the newel post
and its end forms a circular
quadrant in plan.
2. ROUND-ENDED STEP:
Similar to bull nose step inSimilar to bull nose step in
plan, except that ends are
semi-circular in plan.
3. FLIER:
This is an ordinary step of
rectangular shape in planrectangular shape in plan.

18. SPECIAL TYPES OF STEPS:
4 SPLAYED STEP:4. SPLAYED STEP:
This step has one end or
both the ends are splayed
in planin plan.
5. COMMODE STEP:
This step has a curvedThis step has a curved
riser and tread.
.

19. SPECIAL TYPES OF STEPS:
6. DANCING OR BALANCING
STEP:
7. WINDER:
This is a tapering step and it is
These steps do not radiate from a
common center.
This is a tapering step and it is
used to change the direction of a
flight. The winders radiate from a
common centre.

20. TYPES OF STAIRS:
• The clarity of circulation routes in any given building is the determinant
of functional success of the building. Hence, design and construction of stairs
as a mode of vertical circulation is very important.
• The classification of stair types is based on its turning pattern, plan space
occupancy and circulation efficiency.
• The decision to select a specific type of stair in any given building depends
on following criteria:
- Building’s function and surroundings along with the user pattern and userBuilding s function and surroundings along with the user pattern and user
specific requirement
- The desired spatial effect within a building, as Volumetric variation and light
penetration is also guided by the type of stair and its slab cut out patternpenetration is also guided by the type of stair and its slab cut out pattern.
- the required juxtapose of horizontal and vertical circulation; guided by
lobby/landing area of stairs
R ti f il bl i l ti t th l bl fl- Ratio of available circulation space to the clear usable floor space.
- Economic aspect, where the space required by a particular staircase form
could give a quick overview of its economical efficiency.

21. TYPES OF STAIRS
1) STRAIGHT STAIRS:1) STRAIGHT STAIRS:
a) SINGLE FLIGHT (without intermediate landing)
b) MORE THEN ONE FLIGHT (with intermediate landings)
2) TURNING STAIRS:
a) QUARTER TURN STAIRS:a) QUARTER TURN STAIRS:
L-SHAPED
BIFURCATED
GEOMETRICAL QUARTER TURN: - WITH LANDING
- CONTINUOUS
b) HALF TURN STAIRS:
DOG-LEGGED
OPEN-NEWEL: --- OPEN RECTANGULAR WELL
--- OPEN GEOMETRICAL WELL
(With half space or quarter space landings)
--- GEOMETRICAL HALF TURN
(Without landing)
c) THREE QUARTER TURN STAIRSc) THREE QUARTER TURN STAIRS
3) CIRCULAR/SPIRAL/HELICAL STAIRS
4) GEOMETRICAL STAIRS

23. TYPES OF STAIRS
1) STRAIGHT STAIRS:
This stairs run straight between the two floors: i.e. all steps lead in one direction only.
Acceptable solution where space available for stairs is long but narrow in width, i.e. in
case of long street houses or commercial shops where mezzanine floor is required.
However, can also be treated as an architectural element.
As all steps are in one direction, tread-riser ration is more important to achieve the
desirable comfortable pitch.
It may consist ofIt may consist of,
a. ONE SINGLE FLIGHT (without intermediate landing)
OR
b. MORE THEN ONE FLIGHT (with intermediate landings)( g )
Can have structural support on both sides, cantilevered from one side or freestanding.