How to - Decking Subframe styles

PATIO STYLE DECK raft construction
Garden area that drains well.
Remove turf and 100mm minimum of topsoil where deck is to be positioned.
Position a minimum of 2 deck support posts in footings to act as frame anchors.
Replace topsoil with compacted down gravel or hardcore.
Lay weed barrier.
Lay Use Class 4 subframe allowing for 50mm drainage gap all round and attach to post anchors.
Backfill around frame with gravel or pea shingle.
Now fit newels or just deck boards if balustrading is not required.

LOW LEVEL Deck post and beam construction
Limited final deck height
Deck support posts are either supported in 'standoff' proprietary bracket (on footing) or supported in a footing. Joists are attached to beams using mini joist hangers.
Now fit newels or just deck boards if balustrading is not required.

ELEVATED DECK post and beam construction
For sloping sites, multi-tier decks or simply where final deck height is not an issue.
Lateral bracing of the beams may be necessary.
Now fit newels or just deck boards if balustrading is not required.

DECK OVER EXISTING PATIO
on existing structurally sound concrete slab
ie. 100mm slab on top of 100mm compact hardcore.
In this instance 72mm thick beams are supported off the slab using strong angle brackets and durable packing pieces. (45mm thick Use Class 4 joists could also be used for this purpose).
Now fit newels or just deck boards if balustrading is not required.