Low-height or waterproof membrane sub-floor (deck support) system

Futurewood’s new, specially designed aluminium joist and low height adjustable pedestal sub frame system allows for an easy installation of a low maintenance, CleverDeck composite timber deck over a roof top membrane or an ugly concrete patio, balcony, or alfresco area.

The low height sub floor system is designed, as the name implies, to be used in situations where there is a limited amount of height between the proposed deck surface and the external door openings to the home or where there is a waterproof membrane that cannot be penetrated with fixings on a roof top or balcony.

It is an ideal system where there is limited height available due to existing external door heights that open on to the area to be decked or where the objective is to avoid a step and have the deck height meet with the sill or internal floor height.

This system requires a hard, stable, well drained surface for the sub frame to sit on.

Ideally the surface would be a concrete slab or pavers or tiles. If the subframe is being installed over a garden or lawn area, then the area must be well drained. Any vegetation needs to be removed along with loose soil until a hard, stable clay base is established, a geo-membrane should be applied over the bare soil and 300mm x 300mm x 50mm concrete pavers placed over the soil at appropriate intervals to support the subframe.

The sub floor system consists of:

• 50mm x 25mm x 5400mm long black aluminium joists
• Stainless steel, right angle brackets (for aluminium joists)
• Stainless steel, adjustable brackets (for aluminium joists)
• Stainless steel joiners (for aluminium joists)
• 18-30mm adjustable pedestals
• 30-60mm adjustable pedestals
• 60-140mm adjustable pedestals
• Double joist top plates

Using only the aluminium joists as the low height subframe the overall deck height including the 23mm thick decking board is 48mm*.

Using a combination of the adjustable pedestals and the aluminium joists the low height subframe can be set from 43mm – 165mm in height so that when a 23mm thick decking board is added the minimum clearance height becomes 66mm and covers a range up to and including 188mm*.

When additional height is required the 25mm thick aluminium joist can be replaced and a traditional 90mm x 45mm treated pine joist can be used to cover a range of 131mm to 253mm (including the 23mm thick decking board) *.

The aluminium joists and adjustable pedestal sub-frame have been designed and tested for a safe working load of 2KN/m2 (uniformly distributed load) or an applied load located anywhere on the span of the joist of 1.8 KN when supported at 450mm centres. If using timber joists check with the timber supplier but as a typical 90mm x 45mm pine joist is a much thicker and stronger section, the pedestal spacing can be increased to 1100mm + (to be verified by the timber supplier).

The aluminium frame/pedestals do not need to be fixed to the substrate as the combined weight of the system and low height will keep it stable.

*This does not allow for any adjustments that may need to be made for uneven or sloping ground.

For more information about Futurewood’s full range of composite cladding, decking, fencing, or screening, call 1300 484 308, or email [email protected]