STAIRS (PART 1)

STAIRSSTAIRS

Topic: Considerations for stair DesignTopic: Considerations for stair Design

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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 BUILDING3. PITCH 4. TREADS AND RISERS5. WIDTH OF THE STAIRS6 MATERIALS AND WORKMANSHIP6. MATERIALS AND WORKMANSHIP7. HEADROOM8. FLIGHT9. SINGLE STEP10.WINDERS 11.HANDRAILS

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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.

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 cm16 cm x 26 cm17 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.

4. RISEVertical distance between two successive tread faces.

5. GOINGHorizontal distance between two successive riser faces.

6. FLIGHTUnbroken series of steps between landings.

7. LANDINGIt is the level platform at the top or bottom of a flight between floors. Alanding facilitates change of direction and provides an opportunity for takingrest during the use of the stairsrest during the use of the stairs.

8. SOFFITThe underside of a stair.

8. NOSINGIt is the projecting part of the tread beyond the face of the riser. Provided forarchitectural purpose as well as to protect the edge of the step from breaking

d dditi l f t tand additional comfort to user.

9. SCOTIAA moulding provided under the nosing to improve the elevation of the stepA moulding provided under the nosing to improve the elevation of the stepand to provide strength to nosing

11.LINE OF NOSINGS11.LINE OF NOSINGSIt is an imaginary line parallel to the strings and tangential to the nosing. It isuseful in the construction of handrails, giving the line with which the under-surface of the hand-rail should coincide.

12.PITCH OR SLOPEIt is the angle witch the line of nosing of the stair makes with the horizontal.

13.STRINGS/STRINGERSThe inclined member of a stair which supports the ends of steps is known asa stringa string

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.

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.

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 itsimultaneously and for furniture and other things to be carried up and downthe stair.

- The minimum width of the stair should not be less than 80cm. in anycase.

- 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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• 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 heightHeight of riser

• Number of treads in a flight= number of risers-1

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HEADROOMProvision 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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9. SINGLE STEPShould be avoided as it is a discomfort in circulation.

10.WINDERSShould be avoided. If at all required should be designed properly

11.HANDRAILSWhen a flight consists of more than three steps should be provided withWhen a flight consists of more than three steps, should be provided withhandrail. If the width of the stair is more, should be provided at both ends. Inpublic buildings for wider steps should be provided in the centre also. Theheight of the handrail should not be less than 80 cmheight of the handrail should not be less than 80 cm

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TYPES OF STAIRCASESS O S C S S

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SPECIAL TYPES OF STEPSSometimes 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 thebottom of flight. It projectsg p jin front of the newel postand its end forms a circularquadrant in plan.

2. ROUND-ENDED STEP:Similar to bull nose step inSimilar to bull nose step inplan, except that ends aresemi-circular in plan.

3. FLIER:This is an ordinary step ofrectangular shape in planrectangular shape in plan.

SPECIAL TYPES OF STEPS:

4 SPLAYED STEP:4. SPLAYED STEP:This step has one end orboth the ends are splayedin planin plan.

5. COMMODE STEP:This step has a curvedThis step has a curvedriser and tread.

.

SPECIAL TYPES OF STEPS:

6. DANCING OR BALANCINGSTEP:

7. WINDER:This is a tapering step and it is

These steps do not radiate from acommon center.

This is a tapering step and it isused to change the direction of aflight. The winders radiate from acommon centre.

TYPES OF STAIRS:

• The clarity of circulation routes in any given building is the determinantof functional success of the building. Hence, design and construction of stairsas a mode of vertical circulation is very important.

• The classification of stair types is based on its turning pattern, plan spaceoccupancy 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 userspecific requirement

- The desired spatial effect within a building, as Volumetric variation and lightpenetration 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 bylobby/landing area of stairsR 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 formcould give a quick overview of its economical efficiency.

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

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 of It 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.

STAIRS (PART 1)

Design

Transcript of STAIRS (PART 1)