A pergola does two things at once. It changes how an outdoor space feels, and it carries real wind and water loads on top of an entertaining area where you will be sitting with people you like. Getting the second part right makes the first part work.
Here is the list of decisions, in the order they affect the build.
1. Choose the roof style
This is the call that drives everything else, including how much council paperwork you need and how the build comes together.
- Gable. The classic peaked roof. Sheds water beautifully, looks at home against most house styles, gives the best ceiling height under the roof line. Our most common build.
- Skillion. Single-pitch slope. Modern look, low profile, good if you are attaching against an existing wall and want to channel water away from the house. Slightly simpler to frame than a gable.
- Flat. Low-slung. Built with a slight fall (usually one to two degrees) for drainage. Looks contemporary, gives a "ceiling" feel under it. Avoid in very rainy areas because the fall is small enough that any blocked gutter overflows fast.
Material on top:
- Colorbond Trimdek sheeting for full shade and weather protection. Our standard recommendation.
- Polycarbonate (Suntuf or similar) for filtered light. Plants under it actually live.
- Shadecloth (commercial 90%) for the easiest summer-shade option. Will need replacing every eight to ten years.
2. Posts, footings and the wind load nobody tells you about
A pergola is mostly a wind-load problem dressed up as a carpentry job. The roof acts like a sail and pulls hard on the posts when the wind hits broadside. The footings hold it down.
Standard footing on a residential pergola is a concrete pad about 450 mm in diameter and 600 mm deep. That works for most builds in our region. Coastal builds (within a few km of the beach) often need slightly deeper footings because of higher wind ratings and looser sandy soil.
Post material:
- 90 by 90 treated pine. The most affordable option, paintable, our standard for budget builds.
- 125 by 125 treated pine. Beefier look, used on larger structures or for clients who want a heavier visual presence.
- Galvanised steel. Skinniest profile per kN of load, holds the heaviest roof types, gets used a lot on larger spans and any combined deck-and-pergola where post real estate is tight.
Post spacing on standard pergolas is 2.4 to 2.7 metres. Wider spans need either a heavier beam or an intermediate post.
3. When council gets involved
In South Australia, a pergola attached to a residential dwelling will need council application paperwork in nearly all cases. Decking-only builds get a free pass under one metre off the ground. Pergolas do not get the same break because of the wind-load engineering.
What that paperwork actually involves:
- Submitting plans (we generate these as part of the build)
- An engineering certificate signed by a structural engineer (covered by the build)
- A development approval from your local council (the wait is typically two to four weeks in the Fleurieu)
It is the one fixed cost that is the same whether your pergola is twelve square metres or forty, so factor it in early.
4. Attached vs freestanding
This decision changes the engineering and the look more than people expect.
- Attached. The pergola uses your house wall as one of its supports via a ledger board. Fewer posts, less material, less framing visible. Locks the pergola's position in (it has to follow the wall). Good for verandah-style coverings.
- Freestanding. Four (or more) posts of its own. Total location flexibility, can sit anywhere in the yard. Slightly more posts and footings, slightly more material. Best for poolside cabanas, BBQ areas detached from the house, or where the house wall is unsuitable for a ledger (rendered finish, fragile cladding).
Attached is generally a touch leaner than freestanding for the same footprint.
5. Tall pergolas are different builds
Standard pergola height is 2.7 metres at the top of the posts. Anything above three metres becomes "tall" and adds a surcharge because the wind load math changes, the footings deepen, the beams have to be heavier, and the labour to install at height takes longer.
Tall pergolas are worth it if:
- You want headroom for a hanging fan with paddles that will not feel like decapitation
- You want clear sightlines from inside the house to a view
- The house behind it has a high gutter line and a low pergola would look squashed
If those do not apply, stick with 2.7 metres and put the budget into the roof or accessories.
6. Materials and finishes
The decisions that change how the pergola actually looks at the end:
- Frame colour. Auto (natural timber) is the default. Pick a Colorbond colour (Monument, Surfmist, Woodland Grey and so on) for an extra per-m² fee on the pergola footprint and we paint the posts, beams and rafters to match.
- Rafters and battens. The visible underside of the pergola roof. 140 by 45 H3 rafters at 600 mm centres, 70 by 35 battens at 300 mm centres. These are what people notice when they look up.
- Gutters and downpipes. Standard on every pergola now (used to be optional). Colorbond quad gutter, painted to match the roof or the trim, with a downpipe taking water to a stormwater point.
7. Common upgrades worth budgeting for
In rough order of "people add this and never regret it":
- Outdoor ceiling fan. Single biggest comfort upgrade for summer.
- Weatherproof power point. You will need one for the fan, one for fairy lights, one for the speaker.
- Privacy slat screen on one side. Turns a pergola into an actual outdoor room.
- Fluorescent or LED lighting. Makes evening use possible.
Bringing it all together
A 24 m² gable pergola in Colorbond, attached to the house, 2.7 metres tall, with a fan, a power point and a privacy slat on one side is a middle-of-the-road residential build for us. Your site will move that around, but the parameters above cover most of what changes price.
The fastest way to get a real number is to open the 3D Designer and sketch the actual shape and accessories you want. Or contact us and we will work through it on the phone.
Either way: we are a fully licensed building company (BLD319926) and we build a lot of these every year across the South Coast and Fleurieu. Have a look at our recent projects to see what real builds in real backyards look like.
