When does a carport, pergola or deck need approval in the ACT?

Do I need approval for a carport, pergola or deck in the ACT?

You need approval if the structure falls outside either of two sets of exemptions. Building approval (BA) comes from a licensed certifier and is about how the structure is built. Development approval (DA) comes from the Territory Planning Authority and is about what you build and where. Each has its own list of exempt work, and a structure has to be exempt from both to need neither.

Both lists start with general conditions. To be BA-exempt, work must not affect "the structural integrity of any part of a building", a fire-rated element, exits, light, ventilation or fire protection, and it must not involve asbestos. A pergola bolted to the house has to pass that test as well as the size limits.

When does a carport, pergola or deck need building approval?

When it breaks any one of the limits below. Each row lists the conditions it must meet, all of them, to be exempt.

Building (General) Regulation 2008, Schedule 1 Part 1.3 and s 1.1; ACT BA page.

"Partly exempt" means no building approval, but the structure must still be built to the code. Someone has to show that it is, and that is engineering work.

When does a carport, pergola or deck need development approval?

When it breaks the planning limits in the Planning (Exempt Development) Regulation 2023. These are measured from datum ground level, the reference ground level the planning rules use, and many depend on where the structure sits. The front zone is the area between the front boundary and the building line.

Planning (Exempt Development) Regulation 2023, Schedule 1; ACT DA page.

Why can a carport pass planning but still need building approval?

Because the two limits on roof area don't match. Planning allows a carport or pergola roof up to 50 m², but the full building approval exemption stops at 25 m².

Above 25 m², a class 10a structure is at best partly exempt under the "large building" limits: floor up to 36 m², span up to 6 m, the member size limits, and built to the code. Outside those limits it needs a BA. We don't say "anything over 25 m² needs a BA", because that isn't quite the rule. Your certifier confirms which applies.

Worked examples: three common projects

These are illustrative examples, not advice on a particular block. They show how the two tests combine.

A 30 m² carport with no walls, behind the building line

Planning: 30 m² is inside the 50 m² limit, so it can be DA-exempt if it also stays inside the solar envelope and the height limits. Building: 30 m² is over the 25 m² small open building limit. It can be partly exempt as a "large building" if its floor, span and members fit those limits and it is built to the code. Otherwise it needs a BA. Either way, its posts, beams and footings need designing.

Enclosing an existing carport

Building: adding walls ends the small open building exemption. As an enclosed structure it is exempt only within the shed and garage limits, including a roof up to 25 m². Planning: the carport exemption allows no more than 2 walls. Enclose it fully and the shed and garage limits apply, including the area cap for your block size.

A deck 1.2 m off the ground

Building: the floor is over 1 m, so it needs a BA. Planning: it is over the 1 m deck limit too, and within 1.5 m of a side or rear boundary the limit is 0.4 m. Expect a DA as well; your certifier confirms.

What can cancel an exemption?

A structure inside every size limit can still lose its exemption. These conditions apply on top of the tables above.

ACT BA page and Building (General) Regulation s 6; ACT DA page.

Sewer pipes deserve a special mention. Icon Water's carport guidance describes the "zone of influence" as "the area below the ground either side of a pipe where the weight of your structure will impact or place pressure on our pipes", and its guidance says its approval comes before building work, even where no planning approval is required. See our page on building near sewer and stormwater mains.

What if my carport, pergola or deck was built without approval?

It is likely to surface when the house is sold. The ACT seller's building and compliance report must cover every structure: copies of any approved plans, building approval, permit and certificate of occupancy, the writer's view on whether the structure "substantially complies" with the approved plans, whether building approval was required, and if not, whether development approval was.

That is where unapproved decks, pergolas, carports and enclosed carports get flagged. Our guide to the ACT building and compliance report explains the report itself.

Our part is the engineering. An unapproved structure assessment looks at the footings, framing and connections, tells you what the structure needs, designs any upgrade and gives the documents your certifier asks for. It starts at $690 + GST ($759 inc GST). The approval path is your certifier's call.

When should you call a structural engineer?

When the structure is over any exempt limit, partly exempt, attached to the house, close to a sewer main, or already built without approval. Exempt from approval doesn't mean exempt from sound design: a carport roof still has to stay up in a storm, and its footings still have to suit the ground.

• New carport, pergola or deck: carport, pergola and deck engineering from $590 + GST ($649 inc GST): footings, beams, posts, tie-downs and the connection to the house.
• Already built: an unapproved structure assessment.
• Near a sewer main: footing design near sewer and stormwater mains.

For the wider picture, including bigger jobs, read development and building approval in the ACT. We're engineers only: we don't build carports or decks or recommend builders, so the design isn't tied to a product. Send a sketch with sizes and a photo, add up to 5 files, and we reply with a fixed quote in under 20 minutes on average, during business hours.