STAIRCASES

G.NAGESH KUMAR Sr. Asst. Prof.

• Stairs are the medium through which a person can travel from one horizontal level to another horizontal level although it connects two different horizontal levels.

STAIRS

STAIRCASE: A stair is a set of steps leading from one floor to the other. It is provided to afford the means of ascent and descent between various floors of the building. The room or enclosure of the building, in which the stair is located, is known as staircase.

The opening or space occupied by the stair is known as a stairway. In a domestic building the stairs should be centrally located to provide easy access to all rooms.

In public buildings, stairs should be located near the entrance. Stairs may be constructed by timber, bricks, stone, steel or reinforced cement concrete.

• Staircases provide access and communication between floors in multi-storey buildings, and are a path by which fire can spread from one floor to another.

• Staircase, therefore, must be enclosed by fire resisting walls, floors, ceiling and doors. It is desirable that the linings to the walls and the ceilings are non- combustible and 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 floor.

STAIRS AND ITS TYPES

• Single flight straight stairs• Double flight straight stairs• Quarter turn newel• Half turn newel• Open well stairs• Dog legged stairs• Bifurcated stairs• Circular stairs • Spiral stairs• Geometrical stairs

DOUBLE FLIGHT STRAIGHT STAIRS

Here the stairs posses two landings while running straight in the complete flight.

QUARTER TURN NEWEL

In quarter turn newel the stairs run straight in a flight and after reaching the landing the stairs it turns to either left or right at ninety degree and its runs again till it reaches the consecutive horizontal level.

Types of Stairs

Quarter Turn

.

HALF TURN NEWEL

In half turn newel stairs the stairs runs straight and after reaching the landing it turns to left or right and then climbs up to next two to three steps and reaches a landing and these steps again turns in the direction from where the user was approaching reaching finally to the consecutive horizontal level.

OPEN WELL STAIRS

These are like normal doglegged stairs but the only difference is that after reaching the landing the stairs ends up with a railing instead of the wall.

Stair Types

DOG LEGGED STAIRS

Dog legged stairs are the stairs in which the user climbs up to a flight turns at one eighty degree and then climb stairs in opposite direction

BIFURCATED STAIRS

In bifurcated stairs the stairs runs at a flight an as it reaches the landing the stairs runs from left and right side reaching the same horizontal level these stairs are provided generally in atrium of a building.

CIRCULAR STAIRS

The stairs made in in a circular form are known as the circular staircase.

SPIRAL STAIRSThose stairs which are in spiral form is known as spiral staircase.

Spiral

GEOMETRIC STAIRS

Geometric

The technical terms associated with the design and constructions of stairs are:

TREAD: it is the upper horizontal portion of a step upon which the foot is placed while ascending or descending.RISER: it is the vertical portion of a step providing a support to the tread. FLIGHT: this is defined as an unbroken series of steps between landings.LANDING: it is the level platform at the top or bottom of a flight between the floors. A landing facilitates change of direction and provides an opportunity for taking rest during the use of the stair.

Straight Open Riser

Dogleg Closed Riser

Definition – Flights Between Landings

1 Flight2 Flights

Half Space Landing

• Change stair direction 180⁰• Landing width = width of stair (min 750mm)• Used in Dogleg Stairs

Quarter Space Landing

• Change Stair Direction 90⁰• Landing Width & Length = Stair Width• Forms Quarter Turn Stair (min 750mm)

Intermediate Landing

• Allows the Stair to continue in same direction• Required where more than 18 Risers• May be used to give a rest• Width = Stair Width• Length = Stair Width or greater

Quarter Space Landing

RISE: it is the vertical distance between two successive tread faces.GOING: it is the horizontal distance between two successive riser faces. STRINGS AND STRINGERS: these are the slopping members which support the steps in a stair. They run along the slope of the stair.NEWEL POST: newel post is a vertical member which is placed at the ends of flights to connect the ends of strings and hand rail.

BALUSTER: it is vertical member of wood or metal, supporting the hand rail.HAND RAIL: it is the surrounded or moulded member of wood or metal following generally the contour of the nosing line, and fixed on the top of balusters.

• STAIRS OF DIFFERENT MATERIALS• TIMBER STAIRS: these stairs are light in weight and easy to

construct, but they have very poor fire resistance. They are used only for small rise residential buildings. Sometimes, fire resisting hard wood of proper thickness may be used.

• STONE STAIRS: these are widely used at places where ashlar stone is readily available. Stone stairs are quite strong and rigid, though they are very heavy. Stone used for construction of stairs should be hard, strong and resistant to wear. The simplest form of stone stairs is those supported on both the ends, though an open well stair case can also be built.

• BRICK STAIRS: these are not very common, except at the entrance. However, brick stairs of single straight flight are often made in village houses. The stairs consist of either solid wall, or also, arched openings may be left for obtaining storage space.

• METAL STAIRS: stairs of mild steel or cast iron are used only as emergency stairs. They are not common in residential and public buildings, though they are strong and fire resistant. These are commonly used in factories, godowns, workshops, etc.

• R.C.C: these are the stairs widely used for residential, public and industrial buildings. They are strong, hard wearing and fire resisting. These are usually cast- in – situ and a wide variety of finishes can be used on these.

Timber Stairs

Metal Stairs

Concrete Stairs

Stone Stairs

Glass Stair

Combination of Materials

Parts of Stairs

Parts of Stairs

Parts of Stairs

Parts of Stairs

Parts of Stairs

Parts of Stairs

Parts of Stairs

Parts of Stairs

Parts of Stairs

Parts of Stairs

Parts of Stairs

Winders

• Treads that are tapered• Must have same rise as the flights• Maximum of 3 treads per quarter turn• Must be same width at centre on widths < 1m• If stair > 1m same width 400mm from inside

handrail

Winders

MODELS OF STAIRS

Stair Types

Double Closed Stair

Stair Types

Stair Types

Stair Types

Double Open Sided Stairs

In this case one side is closed while the other is open

The Bracketed Stairs refers to decoration & Cut String

Also Known as Cut String

Quarter Turn StairOpen Newel Stair

Spine String Stair

GEOMETRICAL STAIRS

Definitions

Rise & Going must stay the same within flight

THANK YOU

Quarter Turn Stair

http://www.todstairs.com.au/Stair%20Parts/Parts%20of%20a%20STAIR%20diagram.pdf

BCA Requirements

Stair Requirements

Calculate StairNo Restriction on Going

Determine Total Rise = 2700

Select suitable Rise Say 175mm

Divide Total Rise by Rise = 2700/175 = 15.429

Either 15 or 16 Risers = 2700/15 = 180mm 2700/16 = 168.75mmUse 180mm is closer to 175mm

Best Going 2R + G Between 550 to 700Midpoint = 625

Determine Best Going

• BCA states that going must be within the range

• 2 x Rise (R) + Going(G) = 550 to 700• We can assume that the best answer is the

Midpoint (550 + 700)/2 = 625• Best Going 2R + G = 625• Best Going G = 625 – 2R

Calculate StairNo Restriction on Going

Determine Total Rise = 2700

Select suitable Rise Say 175mm

Divide Total Rise by Rise = 2700/175 = 15.429

Either 15 or 16 Risers = 2700/15 = 180mm (Use) 2700/16 = 168.75mm

Best Going 2R + G Between 550 to 700Midpoint = 625

Either

Rise 180Going 265

Determine Best Going 2R + G = 625G = 625 – 2R

Best Going for180 Riser 265 = 625 – 2 x 180

Calculate StairNo Restriction on Going

UseRise 180Going 265

15 Risers

14 Goings

Calculate StairRestriction on Going

Preferred Rise 175mmDivide Total Rise by Rise = 2700/175 = 15.429

Either 15 or 16 Risers = 2700/15 = 180mm 2700/16 = 168.75

Use 180mmDetermine Best Going3800/14 = 271.43 + 2 x 180 = 631. 43 (Closest)3800/15 = 253.33 + 2 x 168.75 = 591

Best Going 2R + G Between 550 to 700Midpoint = 625

UseRise 180Going 271.43

15 Risers

14 Goings

Calculate Stair Flight with Quarter Turn

Stair width 900mmOnce an Intermediate Landing is introduced the top flight becomes constrained

Calculate Stair Flight with Quarter Turn

Stair width 900mm Preferred Rise = 165mm

2700/165 = 16 .364

16 2700/16= 168.75 (3.75 Diff)17 2700/17= 158.824 (6.176 Diff)

Use Rise = 168.75

Best Going = 625 – 2R = 625 – 2 x 168.75 = 287.5

1800/287.5 = 6.261

6 1800/6 = 300 (12.5 Diff)18 1800/7 = 257.143 (30.357 Diff)

Rise = 168.364Going = 300

Best Going 2R + G Between 550 to 700Midpoint = 625G = 625 – 2R

Calculate Stair Flight with Quarter Turn

Stair width 900mm Preferred Rise = 165mm

2700/165 = 16 .364

16 2700/16= 168.75 (3.75 Diff)17 2700/17= 158.824 (6.176 Diff)

Use Rise = 168.75

Best Going = 625 – 2R = 625 – 2 x 168.75 = 287.5

1800/287.5 = 6.261

6 1800/6 = 300 (12.5 Diff)18 1800/7 = 257.143 (30.357 Diff)

Rise = 168.364Going = 300

Best Going 2R + G Between 550 to 700Midpoint = 625G = 625 – 2R

Calculate StairConstrained Flight with Quarter Turn

Stair width 900mm

From Previous we know15 Risers at 180

Length of 1st Flight = 2700 - 900Divide by Best Going = 1800/265

= 6.79Going Either 1800 /6 = 300mm 1800/7 = 257mm

257.14 is Closest to 265

Best Going 2R + G Between 550 to 700Midpoint = 625625- 2 x 180 = 265

Calculate StairConstrained Flight with Half Space Landing

Stair width 900mm Preferred Riser 170mm

3600/170 = 21.176

21 3600/21 = 171.42922 3600/22 = 163.636

Use 171.429mm

Best Going = 625 – 2R = 625 – 2 x 171.429

= 282.142

Length of 1st Flight = 4050 – 900 = 3150

Divide by Best Going = 3150/282.142 = 11.16

11 3150/11 = 286.36423 - 3150/12 = 262.500Use 286.364

Calculate StairConstrained Flight with Half Space Landing

Stair width 900mm Preferred Riser 170mm

Rise 171.429mm

Going 286.364

Calculate StairConstrained Flight with Quarter Turn Winders

Stair width 900mm Preferred Riser 170mm

4100/170 = 24.118

24 4100/24 = 170.83325 4100/24 = 164

Use Rise 170.833

Best Going625 – 2R = BG

625 – 2 x 170.833 = 283.334

2650/ 283.334 = 9.353

9 2650/9 = 294.444 (USE)10 2650/10 = 265

Rise 170.833Going 268.75

Calculate StairConstrained Flight with Quarter Turn Winders

Stair width 900mm Preferred Riser 170mm

4100/170 = 24.118

24 4100/24 = 170.83325 4100/24 = 164

Use Rise 170.833

Best Going625 – 2R = BG

625 – 2 x 170.833 = 283.334

2650/ 283.334 = 9.353

9 2650/9 = 294.444 (USE)10 2650/10 = 265

Rise 170.833Going 294.444

Calculate StairConstrained Flight with Half Space Landing

Stair width 950mm Preferred Riser 170mm

3400/170 = 203400/20 = 170 Rise

Best Going = 625 – 2R = 625 – 2 x 170 = 285

2400/285 = 8.421

8 2400/8 = 300 (15 Diff)9 2400/9 = 266.667 (18.3 Diff)

Rise 170Going 300

Calculate StairConstrained Flight with Half Space Landing

Stair width 950mm Preferred Riser 170mm

3400/170 = 203400/20 = 170 Rise

Best Going = 625 – 2R = 625 – 2 x 170 = 285

2400/285 = 8.421

8 2400/8 = 300 (15 Diff)9 2400/9 = 266.667 (18.3 Diff)

Rise 170Going 300

With all examples either answer will comply and you should consult with your client and/or Architect

Determine Steel Square Mathematically

40mm Margin

Determine Steel Square Mathematically

Determine Steel Square Mathematically

Zoom In

Stair Pitch = 29.54⁰

Determine Steel Square Mathematically

Margin Line

Stair Pitch = 29.54⁰

Determine Steel Square Mathematically

This angle must be the same Stair Pitch = 29.54⁰

Determine Steel Square Mathematically

This angle must be the same Stair Pitch = 29.54⁰

Sin Ѳ = Adjacent / Hypotenuse = 40 ÷ XX = 40 ÷ Sin 29.54X = 81.131

Determine Steel Square Mathematically

This angle must be the same Stair Pitch = 29.54⁰

Sin Ѳ = Adjacent / Hypotenuse = 40 ÷ XX = 40 ÷ Sin 29.54X = 81.13

Determine Steel Square Mathematically

Set Out For Steel Square GoingGoing + Margin ÷ Sin Ѳ= 300 + 40 ÷ Sin 29.54⁰= 381.13mm

Ѳ

Determine Steel Square Mathematically

Set Out For Steel Square Rise

Ѳ

Determine Steel Square Mathematically

Set Out For Steel Square Rise

Ѳ

This Angle must = 90 - 29.54

Determine Steel Square Mathematically

Set Out For Steel Square Rise

Ѳ

This Angle must = 90 - 29.54This Angle must = 29.54⁰

Y = 40 ÷ Cos 29.54⁰Y = 45.9763

Determine Steel Square Mathematically

Set Out For Steel Square Rise

Ѳ

This Angle must = 90 - 29.54This Angle must = 29.54⁰

Y = 40 ÷ Cos 29.54⁰Y = 45.9763

Determine Steel Square Mathematically

Set Out For Steel Square Rise

Ѳ

Rise + Margin ÷ Sin Ѳ= 170 + 40 ÷ Sin 29.54⁰= 170 + 45.98= 215.98