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CARPENTRY - HOUSING

©TAFE NSW Construction and Transport Division 1

Carpentry - Housing

CARP18

Stair Building

STAIR BUILDING


For Construction and Transport Division TAFE NSW Victoria Road Castle Hill NSW 2154 Ph. (02) 9204 4600 First Published 2000 Second Edition 2003 Updated to current BCA 2010 ISBN 0 7348 1014 8 Construction and Transport Division TAFE NSW, 2000 Copyright of this material is reserved to Construction and Transport Division TAFE NSW. Reproduction or transmittal in whole or part, other than for the purposes and subject to the provision of the Copyright Act, is prohibited without the written authority of Construction and Transport Division, TAFE NSW Published by Construction and Transport Division

These notes were prepared by Teachers of Carpentry and ESD Division TAFE NSW 2003 Edition NSW TAFE Commission / DET CONSTRUCTION & TRANSPORT DIVISION WESTERN SYDNEY INSTITUTE OF TAFE 2010 Amended NSW TAFE Commission / DET CONSTRUCTION & TRANSPORT DIVISION Additions made at Randwick TAFE, to bring up to current standard

CARPENTRY - HOUSING


STAIR BUILDING

This text introduces subject matter related to the set out and construction of timber stairs. It builds on knowledge and skills acquired during the first stage, which should be revised and practiced throughout the course. Reference may be made to “Basic Building and Construction Skills”, produced by TAFE and Addison, Wesley, Longman Australia Pty Limited, to re-examine and reinforce these basic skills. The main areas covered are: Internal and external stairs and associated balustrades. Various stair types are outlined, including dogleg, quarter space and single flights. Internal stairs will have closed risers, handrails and balusters, while the external stairs will be open riser with handrails and guardrails. BCA requirements are covered to allow for design and construction of residential stairs, including slope relationship formula (2R + G) and maximum spaces between treads to create safe open riser stairs. Method of setting out, cutting and assembling internal and external stairs is covered as well as the calculation of quantities and cost of materials for both internal and external stairs. Note: This text only covers stair types and stair requirements for residential construction. A comprehensive ‘Glossary of Terms’ is included at the end of this text, which provides a detailed description of trade terms, technical content and some trade jargon.

STAIR BUILDING


STAIRS A stair consists of a number of steps, made up of treads and risers, combined and supported to provide continuous access between floors and/or landings. It may also be referred to, more commonly, in the plural sense as a ‘Stairway’. Note: It is preferable to use the terms Stair or Stairway as opposed to Staircase, which originally referred to the space in which a flight was built.

Fig. 1 Stairs for residential construction

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DEFINITIONS - Stair Types Bracketed stair: Also referred to as ‘Cut and bracketed’, it is a stair with strings having the shape of treads and risers cut out on the top edge and fitted with an ornamental bracket, or fret work, underneath. Circular stair: A stair with or without a central well having steps, which radiate from a common centre. Closed stair: A stair, which has side walls or partitions on both sides and is usually closed by a door at one end. It may also be referred to as a ‘Boxed stair’, or an ‘Enclosed stair’. Closed string stair: A stair in which the treads are not visible in a side view of the stair flight. Dogleg stair: Also referred to as a ’Half-turn stair’, it is a stair with two flights between storeys, which are connected by a rectangular half landing for a 180° turn. The outer strings of each flight are housed into a common newel post, which does not allow for any stairwell. Geometric stair: A continuous sweeping or flying stair, with no newel posts or landings, having a continuous curved string and handrail. It may be designed to fit a semicircular or elliptical stairwell. Helical stair: A stair with a circular plan where all the treads are winders. This stair is also known as a ‘Spiral stair’ or ‘Winding stair’. Open newel stair: An open stairwell with two landings between floors, short flights between landings, and newel posts at the corners. Open riser stair: A stair consisting of strings and treads with no riser boards between treads, thus leaving the risers open. Open stair: A stair, which is not enclosed by walls or separated from the space where it is placed. Open string stair: A stair with a cut string to the shape of the risers and treads, on one or both sides, facing the stairwell. Quarter turn stair: A stair with two flights at right angles to each other with a quarter space landing between them. Return flight stair: A dogleg stair where the outer strings of each flight are vertically above each other. Spine string stair: An open riser steel stair with a single central spine (spine string) and welded tread supports. Winding stair: A circular or curved stair, which changes direction by means of winders, with or without landings.

STAIR BUILDING


Common Stair types Stairs may be designed in a variety of forms to provide practicality, function, decoration and/or aesthetic appeal. Some of the types available are as follows:

Fig. 2 Straight open-riser Fig. 3 Dogleg

Fig. 4 Quarter turn

Fig. 5 Geometrical circular Fig. 6 Spiral or Helical

Landing

Diagonal Bracing

Housed string

SECTION A-A

Tie bolt

First floor landing

ELEVATION 1 Spandrell panelling

Storage under

First floor landing

Ground Floor

First Flight Half Space Landing

Second or Return Flight

Quarter space landing SECTION B-B

Bull Nose step

Quarter space of winder preferably kept to bottom of flight or otherwise avoided

Centre level

ELEVATION ELEVATION

All treads are winders in circular and spiral stairs

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MATERIALS USED FOR STAIRS Stairs may be constructed from a wide range of materials, which include stone, brick, timber, steel, concrete and/or combinations of these. STONE This was probably the first material used for purpose made stairs in the history of building. Evidence of this can be seen in such early structures produced firstly by the Egytians in many of their temples and sarcophagi (burial tombs), then the Greeks in structures found at the Acropolis, followed by the Romans in structures like the Colosseum and the Forum Romanum. Spiral stone stairs were also very popular throughout history with many being used in medieval English castles through to more modern Spanish structures, as found in the towers of Antonio Gaudi’s Sagrada Familia in Barcelona.

Fig. 7 Detail of a typical stone spiral stair flight

STAIR BUILDING


BRICK Small flights of solid brick stairs are used externally for access to and from low patios and verandahs. They are usually laid on a concrete strip footing on either side to support the enclosing wing walls and may have treads constructed of brick-on-flat, brick-on-edge or a rendered brick finish. Dry pressed bricks are preferred for brick stairs and steps as they don’t have holes through them, like the extruded types, and may be laid frog down to provide a neat finish.

CONCRETE Reinforced concrete stairs are more commonly found in commercial construction, however this method of construction may also be used in residential buildings where the upper floor is also concrete. The most common use of concrete stairs in residential construction, is externally from balconies and verandahs.

Fig. 8 Small solid brick flight of stairs

Fig. 9 External reinforced concrete stairs

Brick-on-edge coping to wing wall

Solid brick steps with brick-on-edge treads

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STEEL OR IRON Steel stairs are more commonly associated with external commercial fire stairs, however they may also be used internally. The most common construction type is the spiral stair, used in many Victorian period buildings where narrow building designs only provided compact areas for stairs. Spiral stairs had a revival during the 1960’s and early 70’s in many contemporary cottages, although they were simplified in design and detail using a steel spine and handrail, supporting timber treads. Some newer versions are of all timber construction using modular units and spacers to construct the flight. The tread width in the slope relationship, i.e. the preferred going width to step rise, is calculated at 7/10 (seven tenths) of the distance between the outside of the centre pole and the inside of the handrail. This allows a person to ascend or descend the flight safely and easily.

Fig. 10 Typical elevation and plan of an iron spiral stair

STAIR BUILDING


OTHER TYPES Straight flight steel stairs are most commonly used in commercial work as fire stairs and catwalks. They are normally constructed of galvanised steel with chequer-plate treads and landings, having open risers. Combinations of steel and timber may be used for internal stairs or steel and precast concrete treads for external use. The usual method of design is to have a steel spine or carriage piece with welded angular brackets, to support and provide fixing for the treads. Solid or laminated timber may be used for the treads and the handrails are typically made of fabricated steel.

Fig. 11 Steel external stairs

Fig. 12 Combination stairs

Chequer plate treads

RS stanchion supports

Plan

Section

10mm MS String

RS channel frame to landing

MS handrail

Solid or laminated timber treads

Welded angular brackets

Single steel spine or carriage piece

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TIMBER STAIRS Timber stairs are probably the most common form of stair found in a residential building. They comprise of strings, treads, risers, landings and handrails and are normally closed riser construction, for internal use, and open riser construction for external use. Where the treads and risers are to be covered with carpet the base material may be of structural particleboard or MDF (Medium Density Fibreboard). Timber stairs, which are to be stained or clear finished, are normally made from hardwood timbers, as they provide the best resistance to wear and tear. Commonly used timbers may include meranti, brushbox, Sydney bluegum, jarrah, grey gum, turpentine and many other species. Naturally soft timbers, such as most of the conifers, should be avoided for traffic areas.

Fig. 13 Timber stairs for residential construction

STAIR BUILDING


PARTS OF TIMBER STAIRS String: There may be one or two strings to a flight, which are the inclined sides of the stairs designed to carry the load transferred from the treads and risers. Tread: This is the wide horizontal member between strings to form the top of the step. Riser board: This is the narrow horizontal member between strings to form the vertical face of each step. Nosing: This is the rounded front edge of the tread, which projects past the face of the riser board. Its purpose is to finish the tread edge and widen the tread to prevent the riser from being kicked or scraped. Glue blocks: Triangular blocks of timber fitted under the back of the tread/riser connection to hold the two together. Wedge: These are tapered lengths of timber driven into prepared tapered housings in the string, placed behind the riser and under the tread to ensure a tight top side gap-free fit. Newel post: This is an upright post, to which the strings and handrail are attached. Handrail: A rail fixed between newel posts parallel to the top edge of the string, to provide a safety rail for stair users. Balusters: These are the small sectioned vertical members, with a Max. 125mm opening size placed between the handrail and string. Balustrade: This is the whole framing, which comprises of a handrail, balusters, newel posts and string or kick plate for landing balustrades. Spandrel: This is the triangular shaped space formed between the underside of the string and the floor.

Fig. 14 Parts of the stairs

String

Nosing

Tread

Riser board

Glue block

Wedges

Handrail

Newel post

String

Spandrel

Brackets

Balusters

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LANDINGS A flight of stairs is limited to 18 risers, before it must have a break. This break may be in the form of another floor level or a landing. A landing may take the following forms: Half–space landing: This is a landing formed between flights at 180° to one another, often referred to as a ‘Dogleg’ stair. The length of the landing is equal to the width of the flight and the width of the landing is equal to twice the width of the flight, plus a stairwell if required. Quarter–space landing: This is a landing formed between flights at 90° to one another, often referred to as a ‘Quarter-turn’ stair. The length of the landing is equal to the width of the flight and the width of the landing is also equal to the width of the flight. Intermediate landing: This is a landing formed between flights running in the same direction. The length of the landing is equal to at least the width of the flight and the width is equal to the width of the flights.

Fig. 15 Half-space landing

Fig. 16 Quarter-space landing

Fig. 17 Intermediate landing

STAIR BUILDING


PROPORTIONS OF STAIRS When measuring up for stairs, it is important to know the exact measurements of the length and height of the flight, to allow for accurate calculation of the treads and rises. The following proportions must be obtained: Rise of Flight: This is the vertical distance measured between landings or between finished floor levels. Going of Flight: This is the horizontal distance measured between the face of the first riser and the face of the last riser. Rise of Step: This is the vertical distance measured from the top of one tread to the top of the next tread. Going of Step: This is the horizontal distance measured between the face of one riser and the face of the next riser. (The nosing is not included in this measurement) Note: The rise and going proportions must remain the same throughout the flight(s) of stairs.

Fig. 18 Rise and Going of a flight

Fig. 19 Rise and Going of a step

Going of Flight

Ris

e of

flig

ht

Going of step

Ris

e of

st

ep

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BCA COMPLIANCE REQUIREMENTS Stairs for residential use must comply with the following: Maximum Risers: The minimum number of risers required to make a flight is two (2) and the Maximum number of risers allowed without a break/landing/floor is eighteen (18). Risers and Goings: All risers and goings must be equal throughout the flight or connected flights. Open Risers: Where open risers are used, the gap between the top of one tread and the bottom of the next tread must not exceed 125mm. Note: 125mm is the estimated minimum size of a young child’s head, which if able to pass through the gap would allow the child’s body to follow. Spiral Stairs: These stairs must not be wider than 1.0m and must have the allowable tread width for the stair at seven tenths (7/10) of the flight width out from the face of the central support pole. Flight Width: According to the BCA, there is no maximum or minimum width of a flight for residential construction, however it is suggested that the flight be at least equal to the average width of an adult persons shoulders, which is 900mm. Tread Finish: Treads must have a non-slip finish or have a non-skid strip fixed close to the edge of the nosing. Other critical dimensions are shown on the following diagram:

Fig. 20 Critical stair dimensions

Ceiling line

Handrail

2000

min

.

Newel post

Balusters

865

125 Max.

125 max

1000

min

Note: Minimum stair width is now 900mm see acceptable standards text P. 60 for reference (2010 BCA 14.1)

Note: this distance 2.0m is measured from the “nosing line”, NOT the margin line.

STAIR BUILDING


STAIRS WITH WINDERS An alternative to a single level landing is the use of ‘Winders’, which are normal treads with a tapered length. They have a constant rise to match the other parallel steps and should have a tread going to match other parallel treads, when measured at the centre of the flight width for flights less than 1.0m wide. Note: Flights greater than 1.0m wide should have the tread going measurement at 400mm out from the inside handrail side. Where winders are used instead of a landing, the tread size may be different from the parallel treads provided all the winders are the same size and there are is a maximum of only three (3).

Fig. 21 Layout for stair winders

(Kite winder)

Winders

Proportion for going measured along this line for all treads

1.0m

or

less

Equal Equal

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DETERMINING STEP PROPORTIONS The accepted formula, as per BCA, for calculating riser and tread dimensions for stairs, often referred to as ‘Easy going stairs’, is twice the rise plus one going, or (2R +G). The result of this calculation must fall between 550mm and 700mm, known as the Slope Relationship. TABLE 1 ACCEPTABLE PROPORTIONS FOR STAIRS Calculating Rise and Going for a Flight The basic information required to calculate the rise and going for any flight of stairs is: The rise of the flight; Going of flight and whether it is restricted or unrestricted; and Basic knowledge of BCA requirements and formula for slope relationship. METHOD 1 The following steps outline the method adopted to calculate the rise and going for a given flight of stairs with an ‘unrestricted’ going: METHOD 2

The following steps outline the method adopted to calculate the rise and going for a given flight of stairs with a ‘restricted’ going:

RISER (R) (mm)

GOING (G) (mm)

Min. Max. Min. Max. Min. Max.

SLOPE RELATIONSHIP (2R+G) (mm)

115 190 240 355 550 700

STEP 1 Obtain the rise of the flight;

STEP 2 Assume a suitable rise, when the average rise is (190 + 115) ÷ 2 = 153mm ;

STEP 3 Establish the number of risers by dividing the assumed rise into the rise of the flight;

STEP 4 Establish the length of the going by using the average slope relationship measurement, i.e. ( 550 + 700) ÷ 2 = 625mm, substitute the average rise measurement for ‘R’ in the formula, then transpose the formula to find ‘G’.

STEP 1 Obtain the rise of the flight;

STEP 2 Assume a suitable rise, when the average rise is (190 + 115) ÷ 2 = 153mm ;

STEP 3 Establish the number of risers by dividing the assumed rise into the rise of the flight;

STEP 4 Establish the length of the going by dividing the assumed rise into the restricted flight going. Check to see if both the rise and going measurements comply, by substituting them for ‘R’ and ‘G’, and apply the formula (2R + G).

STAIR BUILDING


Example 1: Using ‘Method 1’, calculate the number and size of the rises and goings for a flight of stairs with a rise of flight of 2.650m and an unrestricted going of flight.

Therefore, there will be 17 risers at 156mm and 16 goings at 313mm. Note: The total length of the flight going will be 16 x 313 = 5.008m

STEP 1 Rise of flight = 2650mm

STEP 2 Assume a rise, say average = (190 + 115) ÷ 2 = 153mm

STEP 3 Number of risers = 2650 ÷ 153 = 17. 320 risers There must be full equal-sized risers, therefore round off to 17 risers. The height of each riser = 2650 ÷ 17 = 155.882, say 156mm

STEP 4 The number of goings will be one (1) less than the risers, therefore 16 goings. The size of the goings will be based on the average slope relationship measurement = (550 + 700) ÷ 2 = 625mm. Now substitute the known measurements for the formula symbols: = (2R+G) = 625 = (312 + G) = 625 Now transpose the formula to find the value of ‘G’: ’G’ = 625 - 312 = 313mm

Fig. 22 Layout of stairs for an unrestricted flight

5008

313

156

2650

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Example 2: Using ‘Method 2’, calculate the number and size of the rises and goings for a flight of stairs with a rise of flight of 1.900m and a restricted going of flight of 3.350m.

Therefore, there will be 12 risers at 158mm and 11 goings at 305mm. Check formula for compliance with BCA (2R + G) = ( between 550 and 700mm) = 316 + 305 = 621mm, therefore it complies.

STEP 1 Rise of flight = 1900mm

STEP 2 Assume a rise, say average = (190 + 115) ÷ 2 = 153mm

STEP 3 Number of risers = 1900 ÷ 153 = 12.418 risers There must be full equal-sized risers, therefore round off to 12 risers. The height of each riser = 1900 ÷ 12 = 158.333, say 158mm

STEP 4 The number of goings will be one (1) less than the risers, therefore 11 goings. The size of the goings will be based on the length of the flight going divided by the number of goings: = 3350 ÷ 11 = 304.5, say 305mm

Fig. 14.23 Layout of stairs for a restricted flight

305

3350

158

190 0

STAIR BUILDING


METHOD OF MEASURING UP for TIMBER STAIRS The accuracy of the finished product will depend on the accuracy of the initial measuring up on-site. There are several points to consider and critical information to record, as follows: Measure the finished floor to finished floor height to establish the rise of the flight, or to

determine whether or not a landing will be required between flights. A more accurate method of establishing the rise would be to mark the height onto a rod or batten;

Check the walls for parallel, square and straight to ensure a proper fit, or to allow for

coverstrips where the strings do not fit neatly to the walls; Check the position of existing windows to ensure the flight(s) do not pass across an

opening; Check the going of the flight for restrictions, e.g. doorways, walls, available headroom,

etc. and record the going of the flight, as required; Note the bearing position for the top of the flight to allow for fixing and finishing of the

top riser and nosing, if required; and Calculate a suitable rise and going for each step, based on the slope relationship formula,

i.e. (2R + G) = 550 to 700mm.

Fig. 24 Check on-site details

Finished upper floor

Proposed stair position

Doorway

Mea

sure

r

ise

Measure available going

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SETTING OUT THE STRINGS Once the rise and going of each step is established, carry out the following:

STEP 1 Select string material, place any bows up and set a margin line from the top edge, for closed strings, to ensure the nosing stays within the width of the string.

Fig. 25 Set a margin line as required

STEP 2 Set up a steel square with the calculated rise and going measurements for each step, including the set back distance for the margin line. Start from one end to allow for riser, newel post and point of attachment notch, then mark out all the rise and tread positions. Note: These set out positions represent the top of the tread and the face of the rise.

Fig. 26 Set out the strings

String

Margin line

String

Margin line Going

Ris

e

Steel square set up for step set out

STAIR BUILDING


STEP 3 Set out for the thickness of each rise and tread, including a stopped housing for the end of the tread nosing, ready to be trenched. The strings should be set out and trenched as a pair.

Fig. 27 Set out positions for treads and risers

STEP 4 Set out the complete string with allowances for wedges under treads and behind risers, tenons into newel posts and reduction of string length to fit between newel posts.

Fig. 28 Complete string set out

Thickness of tread marked

Thickness of riser marked

Top newel post position

End of tenon

Shoulder of tenon

Treads, risers and wedge allowance

Bottom newel post position

Shoulder of tenon

End of tenon

Level cut to bottom of string

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STRING SET OUT TEMPLATE An alternative to setting out individual treads and risers is to use a template, which has the tread, riser thickness and wedge allowance prepared ready to be traced onto the string to suit the particular set out required. The adjustable guides are set to suit the string width being used, which allows the template to slide along after each set out is made. The template may be reversed to set out both left and right strings. The detail below provides set out details to allow for the fabrication of a standard template. Note: A similar template may be fabricated for use with a router. The opening sizes are increased to allow a template guide to be fitted to the base plate of the router, which runs around the tread, riser and wedge outline within the template.

Fig. 29 Typical stair set out template

200

65 65

Wingnut

100

Wingnut

100

30

30mm long Slotted hole

6mm Plywood

60

30

10

0

80

275

550

Wingnut

Sharpened nails in pre- drilled holes

30x18

35

380

60 34

220

DETAIL FOR TREAD and RISER

425

30x18

STAIR BUILDING


ROUTER AND TEMPLATE The quickest way to remove the waste from string set outs and cut neatly to the outline is to use a router fitted with a template guide. A string template may be made by increasing the size of the string template to allow for the thickness of the protruding router template guide. This allows the router cutter to cut neatly along the set out lines and remove the waste at the same time.

Fig. 30 Router fitted with template guide

Fig. 31 Step template for router guide

Step template

Template guide ‘X’ String

Outline for router template guide

‘x’

Allowance for template guide

Original step outline

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STRING / NEWEL POST SET OUT The newel posts are positioned to allow the face of the bottom riser and the face of the top riser to be in line with the centre of the newel post. This means that both these risers will be housed into the newel posts, as well as a portion of each tread and nosing. The ends of the strings are double tenoned, or have a full width tenon, and morticed into the newel posts.

Fig. 32 Set out and jointing of strings and newels

Shoulder line on string material

Newell is positioned with centre line on face of the riser board

Newel

Housing to take nosing and riser

Newel notched for landing trimmer

String

Detail at top of Newel

String

Tread

Double tenon

Newel

Housing to take tread and riser

STAIR BUILDING


HANDRAILS/NEWELS/BALUSTERS There are many different profiles available for handrails, newel posts and balusters. They may be of solid timber sections or be built-up in laminations. Handrail edges are rounded to prevent sharp edges and splintering.

Fig. 33 Typical handrail profiles

Fig. 34 Newel posts and balusters

Newel Posts Balusters

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OPEN RISER STAIRS Open riser stairs are more typically used in external situations and are constructed of durable hardwoods or treated pine timbers. The strings are housed to take treads and prevented from spreading with the use of threaded booker rods. Some suitable Class 1 durability timbers for external stair use, as per AS 1684—Part 2, which may be fully exposed or in contact with the ground, are as follows: Treated radiata pine Coastal grey box Grey gum Forest red gum Red and grey ironbark Messmate Tallowwood Note: Handrails for decks and external stairs are not required unless the top of the landing, or any tread, is more than 1.0m above the finished ground level, or paving.

Fig. 35 Section through open riser stairs

Fig. 36 Isometric view of completed external stairs

Rise of step

Max 125mm space

Rise of step

Booker rod tension bolts

Ground level

Dowel into concrete pad

Horn for fixing

Booker rod tension bolts

Concrete pads

STAIR BUILDING


OPEN RISER STAIRS - Alternative fixing Traditionally, external stairs are fixed using a non-corrosive dowel into a concrete pad, at the bottom of each string, and a timber horn at the top of each tread.

Fig. 37 Use of galvanised metal fixing plates

However, an alternative method of fixing would be to use galvanised metal fixing plates, or shoes cast into a concrete pad at the bottom of the strings, and galvanised metal fixing plates bolted between the top of the strings and ends of floor joists.

Fixing plate

String

Tread

12mm bolt through strings (tension rods)

Fixing plate

SECTION - CLOSED STRING OPEN RISER STAIR

ISOMETRIC VIEW

Max. 125mm

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CONSTRUCTING OPEN RISER STAIRS Open riser stairs are measured up and constructed in a similar way to closed riser stairs, although connection between the newels and strings tends to vary. The balustrade is normally simpler in design, consisting of a handrail, guard rail and newels. The treads may be housed through to the string top edge or they may be housed to take the end section of the tread only.

Fig. 38 Typical open riser flight of stairs onto a verandah

Fig. 39 Optional fitting of treads

Handrail

Guard rail

Landing deck

Bolted connections

Galv. Post shoes

Verandah balustrade

Verandah deck

Threaded booker rod

Threaded Booker rods

G.L.

END ELEVATION ELEVATION Through housed treads

PLAN

125mm max Threaded

Booker rod Preferred 20mm overlap

TREADS - Stop housed TREADS - Through housed

STAIR BUILDING


CALCULATION OF STRING LENGTH Calculation of string length is similar to the calculation of a common rafter. A triangle is formed by the rise of flight, the going of flight and the hypotenuse or string length. An allowance of one (1) step going is added to the going of flight to allow for fitting and finishing of the strings, where they are not mortice and tenoned into the newel posts. Note: Where the going of flight is not restricted, calculation of a suitable step going will have to be calculated, to suit the slope relationship formula (2R + G), then multiplied by the number of treads to obtain the flight going.

Rise of flight =

1.020m, Going of flight = 1.425m ( Rise = 170mm, Going = 285mm)

STEP 1 Check and record measurements for the rise and going of flight. (Calculate going of flight if required)

Fig. 40 Obtaining rise and going of flight

STEP 2 Calculate the length of the string using the following formula:

Length of String = √ ( Rise of flight )² + ( Going of flight + One going of step)²

= √ 1.020² + 1.710²

= √ 1.040 + 2.924

= √ 3.964

= 1.991m

Order 2/ 2.1 Therefore,

Landing and newel posts

Proposed stairs

1020

(Ris

e of

flig

ht)

1425

(Going of flight)

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CALCULATION OF STAIR QUANTITIES Example 1: SINGLE OPEN RISER FLIGHT Calculate the quantity and cost of dressed tallowwood required to construct a single flight of stairs with open risers, when:

Note: Cost of material includes GST

Specification: Rise of flight = 1.550m; Going of flight (restricted) = 2.800m; Rise of step to be around 160mm; String material o/o 250 x 50 DAR tallowwood @ $12.80/m; Treads o/o 325 x 50 DAR tallowwood @ $16.50/m; and Width of flight = 1500mm.

No. of Risers: = 1.550 = 9.688, say 10 risers 0.160

Height of Risers: = 1.550 = 155mm 10

No. of Goings: = (One less than rises), therefore 9

Length of Goings: = 2.800 = 311mm 9

Check: = =

(2R + G) = between 550 to 700

310 + 311 = 621mm OK!

Length of String: = √ ( Rise of flight )² + ( Going of flight + One going of step)² √ (1.550)² + ( 2.800 + 0.311)² √ 2.403 + 9.678 √ 12.081 3.476m Order - 2/ 3.6

Timber Order: = Strings - 250 x 50 DAR Tallowwood - 2/ 3.6 Treads - 325 x 50 DAR Tallowwood - 9/ 1.5 or 3/ 4.5

Cost: = Strings - (2 x 3.6) = 7.2 x $12.80 = $92.16 Treads - (3 x 4.5) = 13.5 x $16.50 = $222.75

Total Cost: = =

92.16 + 222.75 $314.91

STAIR BUILDING


Example 2: SINGLE OPEN RISER FLIGHT WITH BALUSTRADE Calculate the quantity and cost of dressed tallowwood required to construct a single flight of stairs with open risers, including newel posts, handrails and guard rails, when:

Specification: Rise of flight = 1.020m; Going of flight (determined) = 1.425m; Rise of step to be 170mm; Going of step to be 285mm; Width of flight = 1000mm. Size of landing = 1000 x 1000mm; String material o/o 250 x 50 DAR tallowwood @ $12.80/m; Treads o/o 300 x 38 DAR tallowwood @ $11.60/m; Handrail o/o 125 x 38 DAR tallowwood @ $5.30/m; Guard rail o/o 75 x 50 DAR tallowwood @ $3.90/m; and Newel posts o/o 100 x 100 DAR tallowwood @ $7.85/m.

Fig. 41 Open riser flight with balustrade

No. of Risers: = 1.020 = say 6 risers @ 170mm high 0.170



Check: = (2R + G) = between 550 to 700

340+ 285 = 625mm OK!

100 0

(He i

ght o

f han

drai

l)

1 02 0

(Ri s

e o f

f lig

h t)

1425

(Going of flight) 1000

(length and width of landing)

CARPENTRY - HOUSING



Length of String: = = = = =

√ ( Rise of flight )² + ( Going of flight + One going of step)² √ 1.020² + 1.710² √ 1.020² + 1.710² √ 3.964 1.991m Order - 2/ 2.1

Treads: = Order - 5/ 1.0 or 1/ 5.1

Handrail: = Stairs - (same as string), say 1/ 2.1 Landing - 2 sides at 100mm, say 1/ 2.1 Order - 2/ 2.1

Guard rail: = (allow same as for handrails), Order - 2/ 2.1

Newel posts: = (allow 2 for landing), 1.000 + 1.020 = 2.020, say 2/ 2.1 (allow 1 for stairs), 1.000 + (1 rise) 0.170 = 1.170, say 1/ 1.2 Order - 1/ 3.3, 1/ 2.1

Timber Order: = Strings - 250 x 50 DAR Tallowwood - 2/ 2.1 Treads - 300 x 38 DAR Tallowwood - 1/ 5.1 Handrail - 125 x 38 DAR Tallowwood - 2/ 2.1 Guard rail - 75 x 50 DAR Tallowwood - 2/ 2.1 Newel posts - 100 x 100 DAR Tallowwood - 1/ 3.3, 1/ 2.1

Cost: = Strings - (2 x 2.1) = 4.2 x $12.80 = $53.76 Treads - 5.1 x $11.60 = $59.16 Handrail - (2 x 2.1) = 4.2 x $5.30 = $22.26 Guard rail - (2 x 2.1) = 4.2 x $3.90 = $16.38 Newel posts - (3.3 + 2.1) = 5.4 x $7.85 = $42.39

Total Cost: = =

53.76 + 59.16 + 22.26 + 16.38 + 42.39 $193.95

STAIR BUILDING


Example 3: SINGLE CLOSED RISER FLIGHT WITH BALUSTRADE Calculate the quantity and cost of dressed Meranti required to construct a single flight of stairs with closed risers, including newel posts, handrails and balusters, when:

Specification: Rise of flight - 2.500m Going of flight (restricted) - 3.800m Rise of step - around 170mm Strings - 300 x 50 DAR Meranti @ $47.15/m Treads - 325 x 38 DAR Meranti (joined) @ $38.00/m Riser boards - 175 x 25 DAR Meranti @ $10.16/m Nosing - 20mm Width of stairs - 1.100m Handrails - o/o 100 x 75 moulded Meranti @ $35.75/m Newel posts - 100 x 75 DAR Meranti @ $28.28/m Balusters - 30 x 30 DAR Meranti @ $8.04/m Note: Balustrade required on one side only and balusters are spaced at approx. 135mm centres to maintain the 125mm max. space between balus-ters (BCA requirement).

Fig. 42 Detail of closed riser stairs

400

1000

40

770 135

2500

1120

3800

CARPENTRY - HOUSING


No. of Risers: = 2.500 = 14.71, say 15 risers 0.170

Height of Risers: = 2.500 = 167mm 15



Check: = =

(2R + G) = between 550 to 700

334 + 271 = 605mm OK!

Length of String: = √ ( Rise of flight )² + ( Going of flight + One going of step)² √ (2.500)² + ( 3.800 + 0.271)² √ 6.250 + 16.573 √ 22.823 4.777m Order - 2/ 4.8

Treads: = 14/ 1.100 Order - 4/ 3.3, 1/ 2.4

Risers: = 15/ 1.100 Order - 5/ 3.3

Newel posts: = 1.440 + 1.120 = 2.560 Order - 1/ 2.7

Handrail: = (allow same length as string) Order - 1/ 4.8

Balusters: = = = =

(3.800 - 2) 0.135 28.148 - 2 29 - 2 27 (@ 0.770 long) Order - 3/ 5.4, 1/ 4.8

STAIR BUILDING



Timber Order: = Strings - 300 x 50 DAR Meranti - 2/ 4.8 Treads - 325 x 38 DAR Meranti (joined) - 4/ 3.3, 1/ 2.4 Riser boards - 175 x 25 DAR Meranti - 5/ 3.3 Newel posts - 100 x 75 DAR Meranti - 1/ 2.7 Handrail - o/o 100 x 75 moulded Meranti - 1/ 4.8 Balusters - 30 x 30 DAR Meranti - 3/ 5.4, 1/ 4.8

Cost: = Strings - (2 x 4.8) = 9.6 x $47.15 = $452.64 Treads - ( 4 x 3.3) + 2.4 = 15.6 x $38.00 = $592.80 Riser boards - (5 x 3.3) = 16.5 x $10.16 = $167.64 Newel posts - 2.7 x $28.28 = $76.36 Handrail - 4.8 x $35.75 = $171.60 Balusters - (3 x 5.4) + 4.8 = 21.0 x $8.04 = $168.84

Total Cost: = =

452.64 + 592.80 + 167.64 + 76.36 + 171.60 + 168.84 $1629.88

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PATENT-TYPE STAIRS There are patent-types of stairs available, which are pre-fabricated or modular in design. Attic ladders are available, which fold up flush with the ceiling and are easily pulled down when required. Other types include metal modular brackets, which are simply attached to timber strings, similar to those produced by BHP and known as “Kwik-step”. These brackets are nail-fixed on the inside of the string with galvanised roofing nails. The angle is the same for all stairs and the rise may be adjusted to suit by sliding the brackets down the string. Timber treads are bolted through the brackets on the underside. The brackets should be painted for protection from the weather, when the stairs are fully exposed.

Fig. 43 Patent-type modular steps

Fixing Bracket.

Newel post bracket.

Bottom step podium

STAIR BUILDING


GLOSSARY OF TERMS

Aesthetic: This refers to the appearance of an object or its finish.

Attic: This is an accessible area inside a roof space used for storage. Access is normally provided via a fold down Attic ladder.

Booker rod: This is a mild steel or brass rod, which has been threaded for its full length to allow fixing nuts to be placed at any position. These rods are commonly used as tensioning rods to hold open-riser stair strings tightly together and prevent spreading.

Catwalk: Also known as a Crawlboard, it is a narrow, elevated walkway within or above a building or structure, used mainly for maintenance access to plant and equipment.

Chequer(ed): This refers to the non-slip pattern formed on steel or cast-iron plate. It is mainly used on external stair treads and landings.

GST: This stands for Goods and Services Tax, which is a new government tax added to the value of goods, i.e. timber, which was introduced in July 2000.

Spiral: This is a geometric shape made up of a continuous curved line formed by wrapping around a solid or imaginary cylinder.

Winders: These are tapered or triangular-shaped treads formed where the stairs are continuous around a corner to negate the requirement of a landing. The middle winder is commonly referred to as a “Kite-winder”.

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FURTHER READING

Australian Building Codes Board, 1999, BCA (Building Code of Australia), GPO Box 9839 Canberra, ACT. Staines, Allan, Fifth Edition, 1986, The Australian Owner Builders Manual, Pinedale press, Caloundra, QLD. Bloomfield, F. C. and E. Peterson, Revised by B.S. Brown and H. A. Slatyer, First Edition 1958, Fifth edition 1985, The Australian Carpenter and Joiner – Volume 1, Standard Publish-ing Co. Pty Ltd., Naremburn, NSW. Manufacturer’s or suppliers brochures for patent-type stairs.

VIDEOS

Construction and Transport Division, Staircases—measuring up (CTV23) available from Re-source Distribution, Yagoona.

stairs text, updated 2010 - wikispaces.netmikestrade.sydneyinstitute.wikispaces.net/file/view/stairs...

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