Definitions of stair; stair is a set of steps leading from one floor to the other. It is

provided to floors of a building. The room or enclosure of the building in

which the satire is located is known a stair case. The opening or space

occupied by the stairs is known as a stairs way. It should be suitably

located in a building.

• . In a domestic building, the stair centrally located to provide easy access to all the rooms. In public buildings, stair should be located near the entrance. In big buildings there can be more than one stairs may be constructed of timber, bricks , stone , steel or reinforced cement concrete. However, fire protection of stare case is extremely important stair

• case provide access and communication between floor in multi-storey buildings. And are a path by which fire can spread from one floor to anothrer. Stair case, therefore must be enclosed by fire resisting walls, floor ceilings & doors. It is desirable that the lining to the walls & ceiling are non-combustible & of low flame spread. Another important aspect in the design of stairs is the strength aspect.

• . It must be designed to carry certain loads, which are similar to those used for the design of the floor . As part frame stairs, other means it vertical transportation between the floor of a building are lifts, ramps, ladders & escalators.

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• TYPE OF STAIR ;classification based on the arrangement of steps under this classification following are the types of stairs

• Straight stairs• Dog-legged stairs• Quarter turn stairs• Open newel stairs• Bifurcated stairs• Geometrical stairs• Circular stairs

• Straight stairs; In these stairs all the steps lead in one direction. These types of stairs may be continuous of one flight only or maybe split in to more than one flight by interposing a landing. When space available for stairs case is narrow & long, this types of the stair is the only stair which can be installed. Access to entrance, porch etc are provided mostly by straight stair.

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• Dog-legged stair ;This types of consists of two straight flights in opposite direction leaving no space between the flight in plan.

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• Quarter turn stair; a stair tuning through 900

with the helps of level landing is known as Quarter turn stair.

• Open newel stair; In this type of stair, a well or opening. The opening is left in plan between back word & the forword flights. The opening is genera

• Lay of rectangular shape & may be used for installation of lift. This stair requires space more than twice the with of the steps. This stair may consists of two or more straight flights. In inter posed between two or more straight flights. In case of only two flights, a leveled landing is left between back word & ford ward flights .If it is difficult to accommodate all the steps in the two flights, a short third flight heaving 3 to 6

• Steps may be provided along the direction perpendicular to the other long flights. The rtird inter misdate flight. Will have quarter space on its either end.

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• • Bifurcated stair; In this stair a wide common

flight is bifurcated in to two flights with the help of quarter turn mid landing. This stair is widely used these days in modern public as well as residential building.

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• Geometrical stair; this types of stair is similar to the open newel stair is similar to the open stair expect that the well formed flights is curved. Changed of direction in such stairs is achieved with the help of winders & not through landings. These saris may have any geometrical shape & they required no newel postes.Handrailof such stair continues un-inter ruppted with out any angular turn.

• Circular staire;AII the steps in this stairs radiate from a common newel post or well hole. All these steps are the winder. This stairs is provided where space available is limited & where traffic is causalities mostly used to provide access to various floors of multi storied building for service point of the building

• Classification based up on material of stairs;• Classifications of material of stairs are follows;• Timber stair• Stone stair• Brick stair• Metal stair• R.C.C stair • • Timber stair; Timber stairs are light in weight and easy in construction &

maintenance but not fire resistant. They may be used for residential building. Where fire distance of the structure dose not carry any important. Timber stairs can be made suffi

• Ciently fire resistance by adapting hard wood like teak,mahogany.oak etc & by adopting comparatively thick timber members.

• Stone stair;In stone regions where building are made from stone masonry stone stairs are mostly used the stone to be used in stair should be hard strong non-absorbent, fire resisting stone steps may be of different kinds.

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• Brick stair; Brick stairs are not • In common use .However,enterance steps may be

contracted from bricks. In villages bricks stairs for full storey heights are also made. In this case bricks stair may be made solid or arched openings may be left in the solid brick work which are used for making up boards etc.In these stairs treads are kept generally 11/2 wide whereas risers are made equal to two course of bricks.Teards & risers are finished either with cement mortar or with any other suitable flooring material.

• Metal stair;Ccommon metals used for the contraction of stairs are C.I mild steel,or bronze.They are good fire-resisting & heneco,mostly used as fire-escape stairs in factories, godowns,workshops etc. In its simplest form amatal stair consists of steel stringer to with angle irons are welded or riveted & metal plates are used over them as treads.Channels are mostly used as stringers.Treads & risers may be in single unit or in separate units.Treads & risers are supported on angles which are connected to stringers. In same case risers may be completely omitted.

• R.C.C stair; ( Reinforced cement concrete stairs) R.C.C.STAIR are in most common use than all other types of stairs .They can be moulded to any desired shaped & are found to after better resistance to wear & fire. The steps of R.C.C.stairs can be given ordinary of superior cement concrete finishing or may be given materials finishing of superior materials like marble,terrazo,tiles etc.

• • The following are same of the advantage of R.C.C.stairs • They are good in fire-resisting• They are strong,durable,non-slipperly & good loading in appearance• They can be designed for any width,length & loading • Maintenance cost is practically nil.

• The standard Dimensions of stairs;• • Stair, Riser & Tread dimentions;The dimensions of a stair’s, risers & treads should

be proportioned to accommodate our body movement.Their pitch,if steep, can make ascent physically tiring as well as psychologically for bidding & can make descent precarious.If a stairs pitch is shallow,its treads should be deep enough to fit our stride.

• Building codes regulate the minimum & maximum dimensions of Risers & Treads. Some codes specify a maximum riser dimension of 7½inch & a maximum tread of 10 ich ,others limit a riser to 7 inch & regular tread of at least 11 inch .

• Residential stairs are usually allowed to have 8inch risers & 9 inch tread• For comfort the riser & tread dimensions can be proportioned according to the

following formula 2×riser +tread=24 to 25 inch• Exterior stairs are generally not as steep as interior stairs, especially where

dangerous conditions such as snow & ice exist. The proportioning formula can there fore be adjusted to yield a sum of 26 inch.

– THE actual riser & tread dimensions for a set of stairs of are determined by dividing the total rise (the floor to floor height) by the desired riser height. The result is rounded off to arrivided at a whole number to arrive at the actual rise is then redivided by this whole number to arrive at the actual rise height. This riser height must be checked against the maximum riser height allowed by the building code. If necessary, the number of risers can be increased by one & the actual riser height.

• One the actual riser height is fixed the tread run can be determined by using the riser tread proportioning formula i.e (2×riser )+tread=24 to 25(inch).since in any flight of stairs there is always one less tread than the number of risers, the total number of tread than the number riser, the number of treads and the total run can easily be determined

• Building codes base the required width of a stair on the type of occupancy and the occupant load served.

• Pich of the stair; Inclination of stair should not be less than 250 & should not exceed 400 .Too much Inclination require introduction of large risers which is dangerous for the users.Old & weak persons may feel it difficult to use such stairs.Too flat slope is also not consider desirable .

• Head room;The clear distance between the tread & the soffit of the flight, immediatelyabove it should not be less than 2.14m

• RISERS& TREAD;It should be uniform. In order to maintain rhythm while ascending & descending.Usulally 140mm rise & 250 tread are the minimum values. In ordinary buildings maximum rise of 200mm&minimum tread of 250mm may be provided. The following rules are to fix the rizes of rise & tread in a stair

• a),Tread or going in mm +2 X rise in mm=600to 65o • b), Tread or going in mm X rise in mm=40000 to 42600mm (approxi)• c),rise in mm + going or tread imam=400 to 450 • Following may be the usually sizes of steps or rise & tread of steps

140mmX300mm,150mmx 280mm,160mmX260mm,170mmX240mm.•

• THE COMPONENTS OF STAIRS ;a stairs consist s of riser,rise,tread,nosing,going,hand rail,bailuster,soffit,scatial,newel-post,waist,line of nosing,run,head room,header,stringers,landing etc

• RISER; The vertical member of the step is known as riser.It is used to support• & connect the successive tread.• Rise; The vertical, height between two consecutive tread is known as rise.• Tread; The upper horizontal portion of the step over which foot is placed during ascending or

descending a stair way is known as tread.• Nosing; It is the projecting part of the tread beyond the face of the riser. Nosing is usually

rounded to given good aesthetic effect to the tread & make stair stair case consentient & easy to use.

• Hand rail; It is an inclined rail provided at convenient height over balustreades.Inclination of the rail is parallel to the slope of the stair. It serves as a guard rail & provides assistance to the users of the stair .Hand rails can be mounded in so many architectural forms. It also acts as a protective bar.

• Baluster; It is an individual vertical members made of timber,metal or masonry & fixed between string & hard rail to give support to the hand rail.

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• Soffit ;under surface of the stair is known as soffit.It is either finished with plaster or covered with ceiling.• Scotial;It is a sort of additional moulding provided under the nosing or tread to beautify the step in elevation.• Newel-post;It is a vertical timber or steel post provided at the head, foot or at point where the balustrade changes its

direction.Itis also used for supporting the hand rail.• Waist; The thickness of the R.C.C slab over which steps of R.C.C,rest known as waist.• Line of nosing; It is an imaginary sloping line parallel to the slop of the stair & touching the nosing of all the treads.• Run; It is the total length of stairs in a horizontal plan,including landing.• Head Room; It is minimum clear vertical distance between the tread & over head structure (Ceiling etc)• Header; It is the horizontal structure member supporting stair stringers or landings.• String or Stringers;These are the sloping members which support the steps in a stair. They run a long the slope of the

stair. • Landing;It is the level plot form at the top or bottom of a flight between the floors. A landing facilitates changes of

direction & provides an opportunity for taking rest during the use of the stair.• Pitch or slope;Vrtical angle made by nosing line of the stair with the horizontal, is known as pitch or slope of the stair .• Bullnose step ;This step is kept projecting in front the newel post. Its end forms a circular quadrant in plan. This step is

generally provided at the bottom of the flight.• COMMAND STEP; This steps has curved riser & tread• Working line :it is approximate line an the stair, adopted by the stair. This line is located about 40cm from the center of

the hand rail.• Spander;It is triangular framing under the out side string of an open storing stair • Flight;Acontinuous series of steps with out any break between landing & flooring is known as flight.

Cut String

Full String

Newel (post)

Handrail

Riser

Riser: The vertical face of the step of a stair

Tread

Tread: The horizontal face of the step of a stair

Step: The combination of one riser and one treadNosing: The round projected part of a tread to protect the riser from kick

Step

Rise: The total floor finish to floor finish V. height of stairGoing: The total horizontal length of a stair including platform

Flight: a part of stair from floor (landing) to floor (landing) that you move without interruptionLanding: the floor area a the beginning, end or intermediate point of a stairPlatform: intermediate landing

Platform

Landing

Flight Flight

Flight

Head Room: The shortest clear vertical distance b/n the nosing of a tread and the ceiling Stair Case (well): The enclosed chamber into which the stairs are built

Stair Case (Well)

Residential Stairs Requirements

• Min Width of flight is 90cm.• Width of flight = 60 cm x no. of people that pass at a time• Width of landing = Width of flight• The slope of stair should be 30 and 35 degrees.• Min head room = 180cm• Comfortable head room = 210cm• Min Tread Length = 25cm, Max Tread Length = 33cm• Min Riser Height = 15cm, Max Riser Height = 19cm• The max gap b/n balusters = 12.5cm• Height of handrail = 90cm• Tread should be made of non slippery material• Handrails should be made of non temperature dependent material

Stair Calculation

• 2 ( Riser) + Tread = 55 to 70cm• 1st = Determine floor finish to floor finish height = Rise• 2nd = Divide Rise by your choice of Riser• 3rd = Round the calculated Riser to the nearest whole no.• 4th = No. of Tread = No. Risers – 1• 5th = Divide stair length by Tread to find no. of treadsEg. Height of room is 300cm• Choose Riser height = 15cm• No. of Riser = 300cm/ 15cm= 20• If the stair is “ U” Stair = 20/2= 10 risers per flight• No. of Tread per flight = 10-1 = 9• If Tread & width is 25 cm, then stair length • 9 x 25cm tread + 2 X 90cm landing = 405