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Almost a decade ago, Arden streamlined the domestic mono-stringer design for broad application in the Australian market, and with good reason this staircase format has become an industry standard. The MS1 evolves this basic structural technique to create a fully fledged commercial design. The intent of the MS1 is to create a proportionally significant and deceptively simple interior sculpture. Attention is drawn to the contrast in the snaking zigzag of warm polish timber and the linear sweep of the structural steel member, thus emphasising a simultaneous contrast in line and material.

By default, the MS1 incorporates a thick monolithic hardwood tread and riser assembly so that no edge trim is required, and avoiding any possible distraction from the clean geometric lines of the staircase. The mono-stringer’s position underneath and away from the edges of the treads makes it retreat from view, and allows the impression of the staircase to be dominated by the zigzag tread and riser assembly when viewed from a forward position.

Leveraging the strength of structural steel, the central beams of the mono-stringer can span large open spaces without support. Due to its visual simplicity, it can sit equally well in a modern office or public building; either alone, or surrounded by other structures. On exceptionally long spans a central column is applied to add the necessary support, while maintaining a slim metal stringer line.

design

Figure 1. Isometric overview of the MS1 showing a straight flight with landing. A variety of balustrade styles can be applied to the MS1, so a handrail is presented here only for visual reference.

Figure 2. Plan and elevations of a sample MS1 design is indicative of a partial balustrade only.

Clearspace

betweenhandrails

Plinth

FlightOne

Flighttwo

Stringer

Going Landing

Floor cover

Supportpillar

Upper floor

Riser Boards

Treads

Tread support plates

Indicates line of handrail

P 2

AS1428.11 Going+ 300mm

Rise

1000

865 min,1000 max920 recomended

Clearspace

betweenhandrails

Plinth

FlightOne

Flighttwo

Stringer

Going Landing

Floor cover

Supportpillar

Upper floor

Riser Boards

Treads

Tread support plates

Indicates line of handrail

P 2

AS1428.11 Going+ 300mm

Rise

1000

865 min,1000 max920 recomended

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technicalThe core member of the MS1 is constructed from SHS or RHS mild steel sections of a size suitable for the required loads and spans. These sections are mitred and welded at the angle points into a continuous solid member. Support plates for the treads and landings are welded to the core. Mounting plates are also usually welded where required at this stage.

While most mono-stringers only need two support points per flight, it must be kept in mind that the structure must provide strong rotational, as well as lateral and vertical support. Support bindings are usually in the form of a steel mounting plate with at least 4 points for bolts or other attachments. In some cases, the stringer can be welded directly to steel support beams in the existing structure.

Two alternative tread designs are shown. The first shows a solid timber tread. If larger treads are required, solid wood of the required profile may be difficult to source. In this case, an alternative composite tread is applied, comprising a a veneer of dress timber over a structural ply or MDF core. Other designs and materials are possible: refer to Arden technical data sheet ‘A.3 Treads’ for details.

There are also two alternative tread support plate designs. Light duty stairs may use the folded tread plate design. Where high design loads or a wide flight is specified, a heavier gauge steel tread plate is called for. This would make a folded design impractical, and we would therefore recommend the use of the two piece orthogonal welded design.

Screws securetread to riser

Screws secure tread to plate

Vertical plate straddles SHS

Two piece welded orthagonalsupport plates for high load

bearing staircases.

SHS forms main span of mono-stringer

Solid woodtreads and risers

Going

Ris

e

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H

U

Two piece welded orthagonal supportplates for high load bearing staircases.

Solid wood treads and risers

Slip resistant safety stripalso conceals screw heads.

74

32-42

32-42

Going

Ris

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Screws securetread to riser

Screws securetread to plate

Vertical plate straddles SHS

SHS forms main spanof mono-stringer

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Figure 3. Solid timber tread.

Figure 4. Isometric view of solid wood tread supported by welded tread plate and brace.

Figure 5. Elevation with break out section of composite tread supported by folded tread plate.

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Folded tread plate

Slip resistant safety strip

Composite tread and risermanufactured from MDF core with dress wood veneer

Plate straddles SHSfor greater rigidity

SHS forms main span of mono-stringer

Screws secure tread to plate

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Treadthicknessas req'd

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Figure 6. Isometric view of composite tread supported by folded tread plate.

Figure 7. Floor fixing to concrete on non-shrink grout.

Applied nosing/edge trimto conceal end grain.

Slip resistantsafety strip

Folded steeltread plate

Plate straddles SHSfor greater rigidity

Composite tread andriser manufacturedfrom MDF core withdress wood veneer

Screws secure tread to plate

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SECTION R-RSCALE 1 / 50

R

R

T

Non-shrink grout

M16 bolts chemically bonded to concrete floor.

Mild steel base plate

Optional plinth to conceal baseand guard low overhead areas

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AF

Plaster board

Concealedconnection detail

Chemical anchorsfor concrete floors

Top tread flush withupper floor coverings

Riser board

Tread support plate

SHS main span

Upper floor cover

Upper floorconcrete slab

P 10

Suspended ceiling

D

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AE

Visualconnectiondetail

Plaster board

P 9

Edge nosing

Chemical anchorsfor concrete floors

Figure 8. Void edge mounting with visual connection detail.

Figure 9. Void edge mounting with non-visual connection detail.

Figure 10. Non-visual floor fixing method.

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AB

Floor coverings

10mm (typical) base connection plate

M12 chemical anchors

Concrete recessedto conceal connection

35.8°

200

55

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10

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Bracket tosupport landing

Under landing sectionof upper flight stringer

Raked section oflower flight stringer

Dome nuts secure lowerstringer to threaded rodswelded to upper stringer

10mm end platewelded to lowerstringer

P 13

AC

M12 chemical anchors

Concrete recessedand plastered over

to conceal connection

10mm (typical)connection plate

welded to end of SHS

SHS ofstringer

200

P 12

Figure 11. Non-visual wall fixing method.

Figure 12. Typical stringer to stringer connection detail

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complianceArden is a BSA licensed contractor for carpentry, joinery, glass, glazing and aluminium as well as structural metal fabrication and erection. Arden supplies a Form 16 (Licensed Contractor) on all projects. In design and construct contracts, a Form 15 (Design Engineer) certification is supplied upon request. For products and services incorporating the M1 system, this table shows compliance with relevant codes and standards.

full compliance with the codecan comply not applicable to this element

Key

Code Title Applicability

BCA The Building Code of Australia

AS NZS 1170.1-2002 Structural Design Actions – Permanent, imposed and other actions

AS 1288-2006 Glass in Buildings. Selection and installation.

AS NZS 1554.1-2004 Structural steel welding - Welding of steel structures

AS 1554.6-1994 Welding stainless steels for structural purposes

AS NZS 4586-2004 Slip resistance classification of new pedestrian surface materials

AS 1428.1-2009 Design for access and mobility

AS 1657-1992 Fixed platforms, walkways, stairways & ladders. Design, construction and installation

For all commercial applications, it is important that sufficient space for the stairwell cavity be allowed to satisfy Australian Standards and BCA requirements.

The footprint is primarily driven by the floor to floor rise, as well as the staircase configuration chosen. However, stringer and balustrade style design may increase the amount of space required. Allowing too small a cavity can restrict the design options of the staircase. Also, points at where the staircase interacts with other structures are best addressed early in the design cycle.

Consultation with Arden early on will help ensure that these design issues can be addressed in a cost-effective manner.

design note

About this document

Intellectual property is copyright © Archstairs Pty Ltd unless otherwise agreed in writing. All rights to the document are retained. Any use of the document by clients or third parties, unless specifically authorised by Archstairs Pty Ltd, are at their own risk and the user releases and indemnifies Archstairs Pty Ltd from and against all loss or damage arising from such use.

phone (07) 3267 6100 | fax (07) 3267 6500 | email admin@arden.net.au

www.arden.net.au

Office & factory: 46 Radley Street Virginia Qld 4014 Australia Postal address: PO Box 317 Virginia Qld 4014 Australia

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