Basically, a deck consists of boards laid on top of bearer timbers which, in turn, are carried above the ground by various means. Deck boards are typically 19-27mm thick, 75-200mm wide, with a gap of up to 10mm between succesive boards. The bearer timbers typically 75/100x50mm or larger, at approximately 450mm centres, although site conditions generally dictate this dimension.
The diagram above illustrates a basic deck construction. The boards are attached to the bearers with annular nails or screws. The ground beneath the deck should be dressed with a gravel or a geo-membrane to keep down weeds, and the 6mm mesh at the open ends is invaluable for keeping the inevitable crisp packets, Mars Bar wrappers and autumna l leaves from lodging at some inaccesible point beneath the deck.
For fixing decking against walls, a timber referred to as a 'wallplate' is anchor bolted to the wall and joist hangers are used to carry the transverse bearers. Joist hangers are available in a range of sizes to accommodate most bearer dimensions and are affixed via galvanised nails or SS screws.
The bearers can also be carried upon brick or block supports, known as 'padstones', laid on a 75-100mm thick concrete bed and tapped down to level. Alternatively, they can be carried on treated timber ot concrete posts sunk into the ground a minimum of 450mm and concreted in position before fixing the bearers by means of carriage bolts. Timber posts can be rebated to accept the bearer, as shown opposite.

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On sloping ground, the joists/bearers can be carried on a pier of concrete blocks, laid on a concrete bed 75-100mm thick and mortar bedded, or on posts firmly concreted into the ground, as shown in the diagram opposite. An elevated deck such as this will need steps for access.