Best practice guidance for the selection of materials, fixings and finishes
Boardwalks and viewing platforms located in aggressive coastal environments or waterlogged areas require materials which provide operational and maintenance benefits.
Timber should be sourced from Australia and from a sustainable source. Timber joists and bearer sizes should be readily available.
Select materials that are:
Vandal resistant.
Do not sustain combustion (a combustible material will ignite and burn or will add appreciable heat to an ambient fire).
Select high quality materials for high use, high profile areas with emphasis on aesthetics and local character.
Manufactured to engineering specifications (where applicable).
Do not use 150 x 150 mm timber as posts. This will contain untreated heartwood.
Stainless steel horizontal wire barrier is not preferred due to increased maintenance requirement (regular tension tightening) and is prone to vandalism (removal).
Select fixings made of true 304 or 316 marine grade stainless steel.
Top of joists and all cut ends and timber checks are to have an application of CN oil (or equivalent).
Select marine grade stainless steel grips, bolts and brackets which allow straightening of timbers.
Specify CN emulsion (or equivalent).
Ideally select standardised components such as 38 mm thick FRP grate panels.
See Table 1: Materials for further guidance.
Table 1: Materials
Materials
Key considerations
Timber
Must be installed with exposure to adequate sunlight to prevent mould build-up and slippery surfaces
Min treated hardwood (where subject to extreme wetting) with ACQ treatment. Supplier to provide Safety Data Sheet (SDS) for both products. Lanotec or Tanacoat for decking, Ultradeck for handrails and seating (or approved equivalent) protection treatment
Pre-treatment (for exposed end grain sealing to posts and rails): use wood bonding PVA adhesive
Becomes slippery when wet and requires ongoing maintenance
Combustible - ignites and burns slowly
Royal Species Class 1 timbers are ideal for external substructure and decking ie. Ironbark, Spotted Gum, Tallowood, Satinay, Turpentine. Spotted gum is best for decking.
Aluminium
Suitable for full sun or shaded locations, however the surface may become hot
Prevent contact between different metals by providing an insulating layer. This will stop the process of one metal corroding preferentially to another (galvanic corrosion)
Minimal maintenance. Typically used in substructure, stairs and handrails.
Concrete
Suitable for full sun or shaded locations
Pre-cast boardwalk system such as Rocla PermaTrak (or equivalent), a slip resistant pedestrian surface
More expensive than timber, low maintenance. Excellent whole of life costs.
Recycled plastic
Grooved finish for increased slip resistance. Coating available to further increase slip resistance
Additional time may be required for sourcing of replacement parts
Suitable for deck boards, kick rails, hand rail and barrier rail. NOT suitable for structural elements
Suitable for full sun or shaded locations. Highly combustible.
Fibre reinforced plastic (FPP)
No historical data available
Can be installed in shaded areas or full sun – resists mould build-up. Use on beach accesses
Used for structural elements such as deck panels, joists, bearers, piles
Materials must be manufactured and constructed to operate in exposed, high energy environments to achieve the required design life. Select stainless steel considering the following:
True grade stainless steel has been graded by ASSDA (Australian Stainless Steel Development Association) and manufactured by an ASSDA accredited manufacturer.
Stainless steel components must be manufactured to engineering specifications (where applicable).
marine grade 316 stainless steel is required in coastal areas east of Bruce Highway.
note that stainless steel is low maintenance and has a longer asset life.
other material such as 304 grade stainless steel and galvanised steel may be selected for use in hinterland areas west of the Bruce Highway.
Fixings are to include flat washers, spring washers and nuts, secured with thread lock compound (suitable for removal by hand tools). This will prevent loosening of nuts and loss of structural integrity, while allowing replacement of parts.
Nyloc nuts (or equivalent) are a type of lock nut which contains a nylon collar insert that resists turning. These are preferred to prevent release or loosening of thread joints due to vibration, corrosion or temperature fluctuations.
Dyna bolts must be installed and tightened to manufacturers recommendations to ensure they do not work loose.
Pre-grease all bolts with Lanotec lubricant grease (or equivalent) prior to installation.
At locations where bolts would be in contact with corrosive materials (treated timber) or in pivot points, pre-grease all bolts with Lanotec lubricant grease (or equivalent) prior to installation. Remove excess grease from end of thread before applying locking compounds.
Excess bolt protrusion is to be covered with a dome nut, to reduce risk of persons scalping skin when walking past.
Metal brackets are to be flush and free of sharp protruding edges, to avoid injury.
All fixings (fasteners) are to be checked for tightness prior to handover, and re-tightened where required.
The preference for deck boards is countersunk head stainless steel batten screws (6.3 mm diameter, gauge 14), type 304. Do NOT ‘over’ countersink screws as the extra depth holds water.
Pre-drill holes for fasteners, to avoid splitting joists or decking.
Keep screws four times the diameter of the screw head from edge boards.
When face fixing screws, use a staggered alignment at least four times the diameter of the screw head from the edge.
No deck fixing in straight lines as this can cause splitting of joists.
Deck screws should be true 304 grade stainless steel (preferred), reputable brand only (not 316). Tea staining is desirable to dull the shiny surface. Glare can be a problem for people with low vision.
Hot dip galvanised fixings may be used in non-coastal areas if they are dipped in Dulux “Durebuild” GPE ZP (or equivalent).
Hot dipped galvanised bolts must be certified Australian made and manufactured.
Vertical bolts should be avoided as they fill with water. Use SS Triple Grip type connections (or approved equivalent).
See Figure 21: Typical triple grip joist to bearer detail.
Figure 21: Typical triple grip joist to bearer detail
CN oil (or equivalent) – robust oil with additional preservatives, intended for commercial decks. Generally used as the first oil coat on decking.
CN Emulsion (or equivalent) – a grease like timber preservative to be applied liberally to end-grain, cut and checked timber and timber to timber interfaces.
Tanacoat (or equivalent) – a penetrating timber oil which works as a UV blocker and water repellent. Used for re-oiling of existing decks. Suitable for handrails.
Surface coatings or paints are non-penetrating and can crack at fixings and board ends. They let moisture in but not out and require removal and re-sanding to rectify.
Refer to manufacturer/supplier information for installation and maintenance regime.
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Sunshine Coast Open Space Landscape Infrastructure Manual (LIM) DISCLAIMER
Disclaimer
Information contained in this document may change without notice and you should use the current material available from Council’s website and not rely on material previously printed or stored by you.
All figures and diagrams are intended to be used as an aid to design and include Council’s preferred elements but they are not intended to be prescriptive and may need to be varied as dictated by site specific factors. While Council has exercised reasonable care in preparing this document, it does not warrant or represent that it is accurate or complete. The Council will not accept responsibility for any loss, damage, cost or expense that you may incur as a result of the use of or reliance upon any material contained in this document.
This document is produced to convey general information and is not intended to constitute advice whether professional or legal. Any reference to legislation in this document is not an interpretation of the law. It is to be used as a guide only. Consult relevant authority websites for current documents, revisions and amendments.
Where a particular product or supplier is profiled in this document, Council is NOT nominating this product or supplier as the selected choice. Product/supplier information has been provided to allow users to source products which contain the correct elements required for Council embellishments. Each product profiled states ‘or equivalent’ which means that different products may be supplied provided they satisfy the identified performance criteria, recommended standards, equal access guidance and product specifications.
Product design, manufacture and installation requires appropriately qualified people to provide site specific solutions to ensure the embellishment is appropriately adapted to local conditions and data.
This document does not override requirements stipulated in a development approval. Project specific variations may be appropriate as a result of site, environmental or other constraints. Any variations to these standards must be approved in writing by council prior to commencement of variation works. Components of this document may be used within a contract document but users should undertake their own investigations to confirm the information is suitable for this purpose.
Drawings contained in this document are NOT FOR CONSTRUCTION.
Details in this document are deemed to be the minimum standard and the user may wish to apply a higher standard subject to approval by council.
Acknowledgements
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