Decking

This is aimed at helping students understand the design and implementation constraints of decking

Why use Decking?

In my part of Australia timber decking has always been part of the standard design.

It is very helpful at connecting a floor in the house that is elevated above ground level out into the garden.

Relevant Regulations, codes and standards

• National Construction Code - NCC V2 - Part H% Safe Movement and Access

• S1684-2010 Residential Timber-Framed Construction Manual

• Local council rules

NCC 2022 Vol Two H5P2 (1)(a) Ballustrades

BAL level ratings

AS 4586-2013 Slip resistance classification of new pedestrian surface materials

NCC Part 4.2 Footings, slabs and associated elements

AS2870-2011 Residential Slabs and Footings

Clause 54 Standard A10
A new building not on or within 200mm of a boundary should be set back from side or rear boundaries:

• At least the distance specified in a schedule to the zone, or

  1. If no distance is specified in a schedule to the zone, 1 metre, plus 0.3 metres for every metre of height over 3.6 metres up to 6.9 metres, plus 1 metre for every metre of height over 6.9 metres.

NCC Part 12.3 Attachment of framed decks and balconies to external walls of buildings using a waling plate

Types of timbers used

In Australia we have many choices of native timbers. However, we still also have exotic trees shipped over from other countries. This is usually due to price and ease of working with the timbers.

Timbers that are commonly used for decking in Australia:

Australian Highly Durable

• Ironbark

• Spotted Gum

• Black Butt

• Red Gum

Decking and fire

• Some timbers up to BAL 29

• Cover gaps between boards

• Plinth needs to be closed

• Composite boards available

Sealing

• Penetrative

• Top coat

Designing Detailing and Specifying

Questions you will want to think about when designing, specifying and detailing decks

LEGALITIES

• Does this need to be engineered or detailed by a licensed draftsperson?

• Can I simply design what it should look like from the outside and leave the rest for someone more suitably qualified?

• Do I need a balustrade?

• What level of termite protection does it need?

• Is there appropriate clearance underneath for airflow

DESIGN

• What height should it be in comparison to the adjacent surfaces?

• Should it have a framing board around the outside?

• What direction should the boards run

• How wide should the boards be?

• Is it undercover, partially undercover, or open to the elements? Does this effect how the boards will weather in comparison to each other?

TIMBER - SURFACE

• What colour of timber would you like? Is that colour practical in the long term?

• What Durability Class of timber is necessary for the application and expected longevity of the deck?

• What Janka rating of timber is needed for scratch resistance of timber?

• What is the spacing between boards to be?

TIMBER - FRAMING

• What F or MGP Rating?

• What H Grade?

• What class if hardwood?

• What should posts in contact with ground be made of, and do they need any special treatments?

FIXINGS

• Will the fixing pull out over time?

• Should the fixings be hidden or visible

• What should the fixings be made from or coated with?

• Are the fixings suitable for use in treated timber products?

COATINGS

• What do you want the timber to look like in the future?

• Do tannins need to be removed from timber? Does it need to be weathered or stripped before coating?

• At what point should it be coated, before or after installation?

• Should it have a colour tint rather than letting it silver off?

• What product do you want to coat it with?

• Should the constructors adhere to manufacturer’s instructions?

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