A deck extends your living area, providing a level area outside where you can sit comfortably. It is also practical as it will:

• compensate for sloping land
• eliminate the problem of damp or shady areas where grass won't grow
• increase the value of your house.

Size
The size of your deck will depend on the area available, its proposed function and, of course, your budget. You may want to use the deck as:

• a place for children to play
• an entertainment area
• a place for outdoor barbecuing
• a place to relax
• a bridge or walkway
• a surround for a pool, spa or children's sandpit.

A family of four to six people will generally need a deck approximately 12 square metres to be comfortable. This will allow for a table and chairs but not a barbecue or plants. A safe estimate would be 2-2.5 square metres per person.

The location
The ideal location for a deck is on the northern side of the house where it will catch the winter sun. If this isn't possible, build it where it will be most useful. Note where shadows are cast on the ground as the sun moves through the sky from season to season. If necessary, add a screen or covered pergola to protect your deck from wind, rain or strong sun.

Other points to consider are:

• proximity to the house, especially the kitchen or family room
• access to the garden
• views
• privacy (both your own and that of your neighbours).

Types of decks
Attached
An attached deck may be classified as a balcony, porch or patio. It is fixed to the building for stability by means of a ledger, and so offers easy access to the house and its facilities.

Freestanding
A freestanding deck is an independent structure that supports itself. Instead of a ledger it has another row of posts. It is usually set away from the house but can be next to the house if you want to reduce the stress and load on the house and its footings. This type of deck is usually supported on brick piers or posts embedded in the ground. Posts supported in stirrups may be used, but they require additional bracing.

A freestanding deck can be built anywhere in the garden to take in a view, make better use of sloping land or surround a pool. It can be at ground level or raised, and it can be built in any shape, geometric or irregular. Walkways are essentially freestanding decks.

Designing
Once you have determined the function, size and location of your project, lay some timber around to mock up a full size outline of the proposed deck. If you do not have timber available, use rope or even the garden hose to represent the outline.

Test out the area by positioning the tables, chairs or barbecue that will be used on the deck. Can you move around them comfortably? Will there be sufficient room to enjoy your deck? If not, you may need to increase the size or change the shape. Keep in mind, however, that bigger is not always better. Too big a deck can overpower the house and garden.

Be creative with your design but keep it simple or it will be more difficult to build and will cost more. A split-level deck can make building a deck on a steep site much easier, as it reduces the overall height of the construction. It also helps the deck blend into the garden.

Access
If you are attaching a deck to the house, consider how best to ensure a smooth traffic flow from house to deck. Draw a plan of the rooms affected by the deck and map the traffic flow. You may need to move a door or replace a window with a door (this should be done before the deck is built). A double-width door will allow the room inside to operate as an extension of the deck.

Decide whether you want stairs from the deck to the garden and where to locate them so they will provide a convenient entry.

Added features
Rocks or trees can be incorporated into the deck. Deciduous trees give shade in summer and let the sun in during winter. Just allow room for the tree to grow and move with the wind. Lay temporary decking boards that are removed as the tree grows.

Handrails and, perhaps, a pergola can be built as one with the deck by extending the posts up to the relevant height.

Preparing plans
Once you have settled on a design, make some sketches of the deck with the dimensions on them. Discuss these with your local building authority before finalising the project as the building code varies from area to area. You may need to provide larger scale plans (with construction details) and obtain development and building approval before starting.

Parts of a deck

• Baluster Timber that supports a handrail.
• Balustrade Series of balusters supporting a handrail.
• Bearer Timber that supports the joists for floors and decks.
• Brace Diagonal component that stops movement of a structure.
• Fascia board Board fixed to ends of joists to provide a neat finish.
• Footing Part of the construction (usually concrete) used to transfer the load to the ground.
• Joist Timber to which flooring (or decking) is fixed.
• Ledger Horizontal timber member fixed to a wall to carry the rafters.
• Pier Column supporting the bearers for flooring or decking.
• Post In floor construction, the timber or steel vertical used to support the bearers.

Source: Building Decks (Murdoch Books)