Building Decks and pergolas - a planning guide

Pergola, patio or deck, outdoor structures add valuable entertaining space and a design feature.



Humans naturally like shelter and enclosure. Rather than revelling in wide open spaces, when resting and relaxing we’re much more at home when we feel cosy — with a roof over our heads, a protective wall nearby and a level floor on which to stand or sit. The roof, walls and floor don’t have to be heavy and solid. Sometimes a symbolic suggestion is enough, such as an overhead framework, an informal plant screen or a few smooth paving stones.


Garden destination

Building structures in your garden is all about making those friendly, part-enclosed spaces. From a design point of view they also provide a destination so you’re lured out into the garden rather than just looking at it from your back door. There’s nothing as inviting as a pair of comfy-looking chairs set ready for a tête-à-tête in a pool of cool shade, protected by a pretty summer house and surrounded by lush leaves and flowers. Shady zones also add a wonderful contrast element to a garden. By using bright sunlight, dappled shade and deep shade you can highlight different areas.
Shade is another garden essential. We’re all well aware of what prolonged sun exposure can do to skin, so it’s imperative that gardens have places where you can get out of the sun. Little ones especially need protection, and wearing a hat all day is only part of a solution.
Outdoor structures include simple add-ons such as small, open pergolas and decks, larger open structures such as colonnades, or more elaborate and enclosed buildings such as summer houses, gazebos, cabanas and pavilions. Which name you choose for a structure is based more on personal preference and tradition than any real difference in size, materials or purpose.


Planning regulations

When you’re planning to build any structure in your garden, no matter how small and simple, you need to check with your local council about planning requirements and approved construction methods. Recent legislation in several states, including New South Wales, has brought in one set of rules for all local government areas, but in other states it is still a maze of different regulations. Small garden structures may be allowed as exempt development, which don’t require approval, but larger structures, especially those close to a boundary or visible from the street, will need a development application lodged and determined by council. In heritage, fire-prone or cyclone-affected areas, you will need to comply with stricter building codes.
To give you an idea of the kinds of regulations you may be facing, in New South Wales a cabana, gazebo, deck, pergola or patio is considered exempt development if it is on a lot bigger than 450m², is less than 20m² in floor area, is at least 900mm from each boundary, is located behind the building line, and has a roof less than 3m above ground level. In fire-prone areas, where it’s less than 5m from the dwelling, it must be constructed of non-combustible materials. Any walls must be under 1.4m high and the floor level less than 1m above existing ground level. All roof drainage must be disposed of without causing a nuisance to neighbours. There are separate rules governing heritage-listed properties and those in foreshore areas, and limits on the number and total floor area of all additional structures. Rules in other states with state-wide planning legislation are similar but will have minor differences. Your local builder can help advise you with planning regulations.


Size and function

A maximum exempt development size of 20m² is big enough to accommodate dining for six people with room to walk around behind the chairs, but the setting will fill most of the space. If you want to build something bigger than a 20m² floor area, getting a landscape designer involved is a good idea, as they can advise you on siting, access and how to best integrate the new structure into your whole garden.
Start by working out how you plan to use a new outdoor structure. Entertaining is often high on people’s list, but you might also want a covered play area for the kids, somewhere to have a quiet read of the paper, or just a relaxing shady spot from which to enjoy the garden or pool. If it will be located some distance from the house, cooking and eating are not as practical unless you plan to include an outdoor kitchen.
If you have a small garden and can’t fit in anything grand, much smaller garden structures such as arbours, arches and entrance lych gates also have their place. Use them to create instant height in a new garden until the plants grow and for making garden focal points, framing views and providing support for pretty climbing plants. Timber is an easy and cheap DIY option for small structures. Investigate some of the metalwork options available for a real eye-stopper, from artisans such as Gardens of Steel, Entanglements, Dankha and Overwrought. Be very wary of cheaply made imported metalwork arches as many are not weatherproof.


Siting a structure

Siting a structure in your garden is often determined by where you have some level ground, but you might also look at incorporating it into a retaining wall if your block slopes a lot. If you want it to be a garden destination, it needs to be some distance from the house — this can look better as well, as you can be more creative with shapes and materials if you’re not trying to marry it into the look of your home. Maintain a minimum of one metre from boundaries so there’s room for surrounding planting.
If you’d like an open outdoor structure such as a pergola, garden arch or colonnade over which you intend to grow vines, build it to the maximum height you’re allowed. Three metres gives plenty of room for long tendrils to cascade down without getting in your way. When building something tall, choose materials in proportion to the size, as 90mm posts on a tall pergola look weak and spindly.


Taking shape

Traditionally shaped octagonal gazebos and summer houses sit well in old-fashioned gardens. Many companies sell kit-form octagonal gazebos either installed or DIY from only a few metres wide, and a five-metre width will come in just under the 20m² floor area, making it a possibility for exempt development. Rectangles are also available and several companies, such as the Australian Summer House Company, offer bespoke design. Usually built in timber and painted in heritage colours, gazebos can be decorated with powder-coated aluminium lace and fancy timber fretwork. Roofs range from ornate metal domes or traditional-looking asphalt shingles to the downward-sweeping lines of a Federation roof interpreted in Colorbond steel.

A cabana is a covered poolside retreat and businesses selling cabanas usually show them with a distinctly tropical look, although the shape itself can be used for a wide range of styles and locations as the materials you use will alter the final appearance. Often with a square or rectangular floor plan, cabanas in the Indonesian style are also called bales, which typically have heavy column supports, ornate internal timber ceilings and external thatching in either African reed or Balinese alang alang thatch.
Incorporate a smooth, level path to any outdoor structure, especially if you’re likely to be carrying food and drink there. From a design point of view, as a gazebo or cabana shapes an open space or void, it will integrate best with a garden if it’s surrounded by a mass of planting rather than left sitting out on its own.


Building the structure

To get the best results, it's a good idea to employ a qualified builder to build your deck or pergola. But make sure the builder has the experience in this type of work. Builders who specialise in garden structures can usually save you time, hassle and expense.







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