55x40x3mm Aluminium Deck Joist - 5500mm long

55x40x3mm Aluminium Decking Joist – 6060 T6

A 55mm x 40mm x 3mm aluminium decking joist, 5.5 metres long, made from 6060 T6 alloy and finished in satin black powder coat. It's designed to sit on adjustable deck jacks or pedestal decking systems as the subframe for composite or solid timber decking, on raised or low-profile decks alike. Typical joist spacing is 450mm centres, with spans up to 1200mm between deck jacks (600 to 900mm is the more common domestic span), though the page is explicit that spacing and span must suit your specific decking system, loads and project. Fix the joist through the deck jack's bracket holes; Glass House recommends SS304 stainless self-drilling Tek screws (part SS-TS-50-SS304) for this. Engineering documentation is available on request, referencing AS/NZS 1170.0:2002, AS/NZS 1170.1:2002, AS/NZS 1664.1:1997 and NCC 2019; contact Glass House for the Certificate of Compliance or help selecting the right joist configuration for your project.

Build a strong, durable decking subframe with our 55x40x3mm aluminium decking joists, manufactured from 6060 T6 aluminium alloy and finished in satin black powder coat.

Designed for use with adjustable deck jacks and pedestal decking systems, these aluminium joists provide a practical subframe solution for both composite decking and solid timber decking.

Aluminium Joist Specifications

• Size: 55mm x 40mm x 3mm

• Length: 5500mm (5.5m)

• Material: Aluminium alloy 6060 T6

• Finish: Satin black powder coat

• Suitable decking: Composite decking and solid timber decking

• Typical joist spacing: 450mm centres

• Maximum span between deck jacks: Up to 1200mm*

• Typical domestic span: Approximately 600–900mm*

*Joist spacing and spans must be appropriate for the specific decking system, loads and project requirements.

Aluminium Joists for Decking Subframes

The aluminium joists span between deck jacks, creating the supporting subframe onto which the decking boards are fixed.

They can be used with:

• Composite decking

• Solid timber decking

• Adjustable deck jacks

• Pedestal decking systems

• Raised decks

• Low-profile decking applications

Aluminium provides a durable alternative to traditional timber subframes and is particularly well suited to decking installations where a consistent, straight and stable supporting structure is required.

Installation

Aluminium joists are typically installed at approximately 450mm centres, subject to the requirements of the decking manufacturer and individual project design.

The joists can span up to 1200mm between deck jacks, with spans of approximately 600mm to 900mm commonly used in domestic applications.

Fix the aluminium joist through the deck jack support bracket holes.

We recommend SS304 stainless steel self-drilling Tek screws for fixing the joist to the deck jack support bracket.

Recommended fixing: SS-TS-50-SS304

Always confirm joist centres, spans, fixing requirements and structural requirements for your specific decking system and application.

Engineering & Compliance

Contact us for the Certificate of Compliance for the design capacities of our extruded aluminium joists, referencing:

• AS/NZS 1170.0:2002

• AS/NZS 1170.1:2002

• AS/NZS 1664.1:1997

• NCC 2019

Contact our team if you require compliance documentation or assistance determining the appropriate joist configuration for your project.

Collection Locations

Free collection is available from:

• Gold Coast

• Brisbane

• Adelaide

• Melbourne

• Cardiff

• Perth

Aluminium Joist Delivery Areas

Delivery is currently available to:

• Sunshine Coast – as far north as Noosa

• Brisbane metro

• Gold Coast

• Northern Rivers – north of Ballina

• Tweed

• Melbourne metro

• Adelaide metro

• Cardiff metro

• Perth metro

Outside these delivery areas? Contact us with your location and project requirements and we'll advise whether delivery can be arranged.

Common questions about the Aluminium Joist

What is this aluminium decking joist, and what's it made from?

A 5.5 metre length of 55mm x 40mm x 3mm aluminium joist in 6060 T6 alloy, finished in satin black powder coat, used as the subframe under composite or timber decking.

Who is this decking joist designed for?

Deck builders and installers or DIYer’s using adjustable deck jacks or pedestal decking systems, for either composite or solid timber decking, on raised or low-profile decks.

What decking systems and fixings does this joist work with?

It works with adjustable deck jacks and pedestal decking systems, fixed through the deck jack's bracket holes. Glass House recommends SS304 stainless steel self-drilling Tek screws (part SS-TS-50-SS304) for the fixing. Bought seperately.

What span and spacing should I use with this joist?

Typical joist spacing is 450mm centres, with a maximum span of up to 1200mm between deck jacks; 600mm to 900mm is the more common span in domestic applications. The page is explicit that these are typical figures only, your specific decking system, loads and project design determine the actual spacing and span you should use.

When would this joist be the wrong choice, or need engineering sign-off?

The stated span and spacing figures are typical guidance, not a substitute for confirming your specific decking system's requirements, loads and structural needs. For a documented design capacity, Glass House provides a Certificate of Compliance on request, referencing AS/NZS 1170.0:2002, AS/NZS 1170.1:2002, AS/NZS 1664.1:1997 and NCC 2019; contact them rather than relying on the typical figures alone for a load-bearing or council-assessed application.

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Related products

• SS304 self-drilling Tek screws (SS-TS-50-SS304)