So to comply with these requirements, what are the installation options and costs for decking or tiles solutions installed over a waterproof membrane deck? Have a look at the chart above for the cost comparisons of floating deck and tile options.

Trafficable membrane:

A select few membranes can withstand some traffic, such as Nuralite's Nuradeck or Skellerup's DecKing. Installed prices range from $60m²-$247m²
There are two advantages and eight disadvantages of using a traffic able membrane, available here.

Tiles on deck jacks or screw jack pedestals:

Installed prices range from $183m²-$398m². There are four advantages and 12 disadvantages of using tiles on deck jacks, available here. 

Timber decking on frames:

Installed prices range from $308m²-$353m². There is one advantage and 11 disadvantages of using timber decking on pine substrate, available here.

OUTDURE'S QWICKBUILD deck-frame system with ECO-DECKING timber composite decking:

Installed prices range from $265m²-325m².

The 20+ advantages of using ECO-DECKING on QWICKBUILD are:

• Ensures sufficient airflow
• Allows easy access to clean out debris in gutters and downpipes
• Allows easy access to inspect membrane, decking boards and ventilation/access grates can be removed without damage
• If inspection of the membrane is required, decking boards can be uplifted and reinstated at a fraction of what it would cost to do the same with timber decking
• Rigid, stable deck-frame system
• Decking boards are not permanently fixed to the subframe
• Materials do not absorb moisture so do not increase in weight when wet
• Light weight – doesn't required any re-engineering
• Can span over gutters/downpipes easily from 1.3 m-4.8 m spans
• Cantilevering joists is no problem – perfect for over gutters/downpipes
• Supplied as either made-to-measure frames or in kitset form
• Made-to-measure frames are pre-assembled off-site
• Construction and installation are not weather-dependent
• Easily handled by two people
• Only four screws per panel to assemble
• Fast and clean on-site installation, very little swarf, 0-3% wastage
• Aesthetically pleasing board layout
• Can easily create picture frames or breaker board details
• Requires fewer deck jacks
• Deck is flush with internal floor level.

The one disadvantage is that many builders have never used such an efficient decking system and don't know how to price for installation. That problem is easily fixed with a five-minute phone call.

BRANZ suggests 1.5 degrees minimum, but recommends 3 degrees.

Councils design requirements falls for membrane decks or traffic able surfaces laid on top of them:

• Councils will not approve direct fixing of tiles laid over a timber frame and substrate; only direct fixing onto membrane with a concrete substrate is allowed
• If tiles are to be laid, they must be laid over a floating deck, which must provide adequate clearance for ventilation purposes and not be permanently fixed to the membrane
• The deck or balcony membrane system must be maintainable. One way of achieving this is by designing a removable proprietary floating tile or timber system on pads or feet
• The decking or tile surface must allow access to gutters and downpipes for the property owner.

For more information about the true installation costs of tiles or floating decking on membrane decks, click here.