STAIRS

1

Stair

2

OVERVIEW

• Introduction

• Functional requirements

• Basic elements of stairs

• Type of stairs

3

StairINTRODUCTION

What is vertical movement or vertical circulation?

• Circulation is a movement of human and goods between interior spaces in the building to the entrance or exit.

• Can be channeled through several types – passageway, corridor, stairs, ramps, etc.

• Vertical circulation is movement of human and goods between stories of a building.

• Classified into 2 classes;

• Class 1 system – ramps, staircase, elevators, escalators.

• Class 2 system – mainly not for human, e.g. dumbwaiters.

4

StairINTRODUCTION (cont.)

5

StairINTRODUCTION (cont.)

STAIRS/STAIRWAY

• A set of steps formed to make it possible to pass to another level on foot by putting one foot after the other on alternate steps to climb up or down the stair.

• Stairs can be made of concrete, stone, wood, steel or combination of any of these.

6

Stair

INTRODUCTION (cont.)

LADDER

• A series of narrow horizontal steps fixed between two upright of wood or metal, on which a person usually climbs up or climbs down facing the ladder.

• Usually fixed in an upright, near vertical position or more at a shallow slope for ease of use. Therefore, it only occupy the least floor area.

• Not suitable for elderly and handicapped and as a mean of escape in case of fire.

• Should only be used for access to loft conversion of one room, where there is not enough space for a stair, and that should be fixed in position and fitted with handrails both sides.

7

Stair

INTRODUCTION (cont.)

STEPLADDER

• A series of comparatively narrow, flat, horizontal steps, fixed between two vertical upright, which provide more comfortable and secure support for the foot than the slim.

RAMP

• A ramp is a surface, sloping uniformly as an inclined plane up and down which a person may pass on foot between levels.

• Formed at a slope of at least 1:20. Thus, it occupies a considerable area, usually adjacent to a long, low building.

8

Stair

FUNCTIONAL REQUIREMENTSSTRENGHT

• Able to support for movement between floors, including dead and imposed load.

SAFETY IN USE• Comply with the Building Regulation in determining the rise,

thread, headroom and dimensions of the handrails and guarding.

• Should be constructed of materials that are capable of maintaining strength and stability for a period of time sufficient to escape to the outside.

FIRE SAFETY

• The steps and the width should be adequate for the safe escape to the outside.

9

Stair

PRIMARY FUNCTIONS

• Provide an access from one floor to another.• Provide a safe means of travel between floors.• Provide a degree of insulation where part of a separating

element between compartments in a building.

• Provide an easy mean of travel between floors.• Provide a suitable means of escape in case of fire.

• Provide a mean of conveying fittings and furniture between floor levels.

StairSTAIR TERMINALOGY

10

11

Stair

STAIR TERMINALOGYSTEPS

• A series of horizontal open treads with a space between the treads with a space between the treads or as enclosed steps with a vertical face between the treads.

• Tread – horizontal surface of a step

• Riser – vertical surface or near vertical of a step

12

Stair

STAIR TERMINALOGY (cont.)FLIGHT

• Uninterrupted series of steps between floor and landing, or between landing and landing.

• A flight should have no fewer than 3 steps and no more than16 risers.

• The rise and tread in one flight and landings between floors should be equal.

• The rise and tread should have the same size to avoidinterruption in the rhythm of going up or down.

• The dimension of the riser and thread will determine whether the stair is steep or shallow.

13

Stair

STAIR TERMINALOGY (cont.)FLIGHT (cont.)

• The dimensions will depends on the function of the building and should comply with the Building Regulation (UBBL), e.g. Section 40.

• The steeper stair will save more space and is accepted for houses because the occupants are more familiar with the stair.

• The shallow stair requires more area but suitable for public building to minimise danger to the public escaping via stair during emergency.

14

Stair

STAIR TERMINALOGY (cont.)HEAD ROOM

• A clearance height between the pitch line of the stair and the underside of the stairs, landings and floors above the stair.

• Minimum 2 m clearance from the pitch line for a convenience of human and goods movement.

15

Stair

STAIR TERMINALOGY (cont.)Baluster

• Vertical stand that supports handrails for security purposes.

• Can be made from timber or steel.

• Can be bolted to the sides of flights or through the material, grouted or set in mortices either cast or cut in the material.

Handrail

• Horizontal member fixed on the top of series of balusters.

• Can be made from timber or steel.

Balustrade• A series of baluster, capped by a handrail.

Stair

STAIR TERMINALOGY (cont.)

Closed railing

Open railing

17

Stair

TYPE OF STAIRS

• Type of stairs:

o Straight flight/straight run

o Quarter turn/L-shaped

o Half turn (dog leg)/180 return

o Spiral (helical) & elliptical

o Winder

18

Stair

TYPE OF STAIRSStraight Flight Stair

• Rises from the floor to floor in one direction with or without an intermediate landing.

• Known as ‘cottage stair’ as well, commonly used in the traditional ‘two-up two-down’ cottage.

• The most economical use of the straight flight is to locate the stair in the centre of the plan running for front to back.

19

Stair

TYPE OF STAIRS (cont.)

Quarter Turn Stair/L-shaped

• Rises to a landing betweentwo floors, turns through 90˚,then rises to the floor above.

• Good in compact planning.

• The quarter turn sometimewill be replaced with windersfor economic use of space.

20

Stair

Half Turn (Dog Leg) Stair

• Rises to a landing between floors, turns through 180˚, then rises parallel to the lower flight to the floor above.

• The most common arrangement of stairs.

• Advantage – can be constructed within the confined vertical stair well.

21

Stair

Spiral & Elliptical Stair

• Constructed as either a spiral(helical) stair or an ellipse stair.

• The most economical way to save space, but difficult to use due to the sharp turns. Very dangerous for the very young and elderly.

• Usually use where the space is very limited for access to an intermediate floor of one room.

Spiral (helical) stair

Elliptical

22

Stairstair

TYPE OF STAIRS (cont.)

Winder Stair

• Triangular treads/tapered treads that wind around quarter of half turn in place of landings.

• To reduce the number of steps required in the rest of the stair and to economise in space.

• Usually use in domestic stairs.

• Can be hazardous as they only offer little foothold at the interior corner.

• Not recommended for public buildings

in the means of escape stairs especially for the very young and elders.

Stairs can be made of :

• Timber

• Concrete – precast & cast-insitu

• Metal

• Stone

Timber Staircase

• Constructed from timber board

• Common use in domestic work.

• The design of stairs flight landings or tapered steps is depend on the space to accommodate it.

• Handrail balustrading is important to provide visual andpractical safety barrier to the side of stairs.

Stair

25

26

Stair

Timber Stair (cont.)

Tapered stairs/winder

• Frequently used because can use space economically

Open tread stairs

• Closed string• Cut strings or carriages• Mono-carriage• Alternating tread stairs

Timber Stair (cont.)

Timber Stair (cont.)

Open riser stairs Closed riser stairs with housed stringer

Alternating trade stairs

• Application – access to domestic loft conversion only

• Very steep pitch – very economicuse of space

• Not very safe.

Reinforced Concrete Staircase

• Can be cast in-situ, precast or combination of both.

• Better fire resistant from timber staircase.

• Common use in multi-storey building.

• Can be formed as straight flight, quarter turn, half turn orgeometrical. But, the usual form is half-turn.

• The construction of the staircase depends on the structural of the building and the convenience in casting the stairs in situ or the use of reinforced concrete support and precast steps.

TYPE OF STAIR (cont.)

In-situ RC stair

• Variety of stair types and arrangements are possible, which of having its own appearance , characteristic and method of construction.

• Common use as it is non-combustible, stronger andhardwearing.

• Will maintain its strength and integrity for a reasonable period during an outbreak of fire. Therefore, it is more suitable than timber stair as an escape route.

• Typical in-situ RC stairs are:o Inclined slab stairo Cranked slab stair

o String beam stairo Cantilever stair

TYPE OF STAIR (cont.)

Inclined slab stair

• Constructed when there areLB wall around the

stair.

• The landing is built into thewalls as one way span slab.

• The flight span from floor to landing and landing to floor.

• Disadvantage – wasteful cutting of brick or block to allow the flight built into

the walls.

TYPE OF STAIR (cont.)Cranked slab stair

• The stair is constructed as a cranked (bent) slab spanning from landing to flight and to landing with no side supports.

• This type of construction only use when the landings can not gain support each side of stair.

• Disadvantage – more costly

TYPE OF STAIR (cont.)String and trimmer stair/String beam stair

• The landing beams are supported by side walls (LB) or the beams of the frame andin turn support inclined beamsthat support the flight.

• Disadvantages - cause untidy soffit or underside of the stair.

• Best suited for to the use of precast concrete steps and precast landing.

TYPE OF STAIR (cont.)Cantilevered stair/cantilevered spine wall

• Constructed to cantilever from the spine wall, or can be partly cantilever from thespine wall and supported bythe enclosing frame or walls.

TYPE OF STAIR (cont.)

Precast Concrete Stair

• Can be produced to most of the formats used for insitu RC stair.

• Seldom used because of the majority using cast in-situ method.

Common use for aesthetic reason.

• Advantages –

o good quality control of finished product

o no formwork thus no storage required and save the site space

o stair can be installed at any time, thus the stair shaft can be used for other purposes e.g. for lifting or hoisting space

o Hoisting, positioning and fixing of stair can be carried out by

semi-skilled worker.

TYPE OF STAIR (cont.)

Stone Stair

• Traditionally constructed using natural stone as the steps.

• Can be formed as:

o Rectangular/stepped soffit

o Flush soffit

• The end of the steps are built into the walls. The landings are constructed using one or more large slab of natural stone built into enclosing walls and bearing on the steps below.

TYPE OF STAIR (cont.)

Stone Stair (cont.)

Stone steps with stepped soffit Stone steps with flush soffit

Metal Stair

• Can be produced in cast iron, mild steel or aluminium alloy forboth external and internal used.

• Usually is custom made, therefore is more expensive.

• Steel channel section serves as stringer.

• Treads can be in the form of steel pan filled with concrete,steel flat plate with textured top surface or bar grating.

• Can be painted or covered with concrete for fire safety reason.

• Advantage – no need formwork during construction.

• Disadvantage – regular maintenance in the form of painting.

Metal Stair (cont.)

Simple ReinforcedConcrete Stairs

Formwork

Reinforcement

Metal stairs

Timber Spiral Stair

Precast Stairs – hoisting and assembling

Precast Stair

REFERENCES

1) R.Barry,1992, The Construction of Building,Vol. 2, 5th ed, Blackwell Science Ltd.

2) Frederick S. Merritt et. al, 2001. Building Design andConstruction Handbook, 6th ed., McGraw Hill.

3) Roy Chudley, et.al, 2005.Building Construction Handbook

,5th ed, Elsevier.4) Francis D.K.Ching, 1991, Building Construction Illustrated,

2nd ed.,Van Nostrand Reinhold.