Preliminary Planning Assessment NSW: Why "It's Just a Deck" Can Still Require Council Approval

A deck, a carport, a garage conversion, a pergola. These are the kinds of works most homeowners assume fall under the no-approval category.

In many cases they're right but the operative word is assume, and in NSW planning, an assumption that turns out to be wrong can mean a stop-work order, a demolition order or a problem that surfaces at the worst possible time, when you are trying to sell.

A Preliminary Planning Assessment (PPA) is a professional planning review that confirms whether proposed works on your property qualify as exempt development under NSW legislation before any money is spent on materials or a builder.

It takes the guesswork out of a question that sounds simple but depends on a specific set of site conditions that most homeowners have never checked.

What Exempt Development Actually Means in NSW

Exempt development is defined under the State Environmental Planning Policy (Exempt and Complying Development Codes) 2008, known as the Codes SEPP. It refers to minor, low-impact works that can be carried out without a Development Application (DA) or a Complying Development Certificate (CDC), provided every applicable development standard is met in full.

The key phrase is every applicable standard .

Exempt development is not a general permission to carry out minor works. It is a legislative pathway that applies only where a specific checklist of criteria is satisfied for your specific site. Miss one criterion and the works are not exempt, regardless of how small or straightforward they appear.

The Codes SEPP sets out separate standards for each type of work. A deck, a carport and a garage each have their own size, height, setback and material requirements. Across all of them, a set of general exclusions also applies.

Exclusions disqualify entire categories of land from the exempt development pathway entirely, no matter how well the proposed works would otherwise comply with the specific standards.

The Site Conditions That Remove Exempt Status

These are the most common reasons a homeowner discovers, too late, that their project was not exempt.

Heritage listings and conservation areas

Exempt development cannot be carried out on land that contains a heritage item listed on the State Heritage Register or that is subject to an interim heritage order.

Beyond state-listed items, the Codes SEPP imposes additional restrictions on properties within a heritage conservation area or a draft heritage conservation area designated under a Local Environmental Plan (LEP).

A deck or pergola in a heritage conservation area may still qualify as exempt if it is positioned behind the building line of any road frontage, but a carport or garage in the same location faces tighter constraints.

Many homeowners are unaware their property sits within a conservation area boundary at all. It does not require the house to be individually listed. A whole street, suburb precinct or neighbourhood can be mapped as a conservation area under the relevant LEP, and that designation applies to all properties within the boundary.

Bushfire prone land

Properties on bushfire prone land face additional material and construction requirements under the NSW Rural Fire Service's Planning for Bush Fire Protection framework. For decks, patios and pergolas within 5m of a dwelling on bushfire prone land, the Codes SEPP requires construction from non-combustible materials.

Beyond that, some works on bushfire prone land cannot proceed as complying development at all which means the exempt development pathway is also affected.

Bushfire prone land mapping is administered by councils and certified by the NSW Rural Fire Service and it covers a significant proportion of properties across Greater Sydney, the Central Coast, the Blue Mountains, the Hunter and regional NSW.

Flood controls

Flood risk overlays sit within LEPs and can affect what is permissible on a site and how any approved structure must be designed. Works on flood control lots face specific restrictions under the Codes SEPP, including prohibitions on earthworks and retaining walls.

For garage conversions and enclosed structures, flood controls can affect floor levels and materials in ways that remove the exempt development pathway entirely and redirect the proposal to a DA.

Size and setback thresholds

Even where none of the above apply, the dimensional standards for exempt development are specific and unforgiving.

A detached garage must not exceed 20sqm in floor area to qualify as exempt, with a maximum wall height of 2.4m and a ridge height of 3.8m, and must maintain a 900mm setback from rear and side boundaries.

A deck must not exceed 25sqm and must be no more than 1m above ground level.

A carport must have at least two sides and not less than one-third of its perimeter open.

These thresholds are precise. A structure that is 21sqm does not qualify under the 20sqm cap regardless of any other factors. There is no margin and no discretion.

Lot size and existing approvals

The Codes SEPP also imposes restrictions based on lot size, and the interaction of proposed works with existing structures and approvals matters. Adding a carport to a dwelling where the combined floor area of the dwelling and all outbuildings would exceed the maximum site coverage allowed under the LEP can remove the exempt pathway.

A garage conversion that creates a habitable space changes the classification of the structure, which takes it out of the Class 10 non-habitable building category that exempt development applies to.

What Can Go Wrong Without a Planning Check

Stop-work orders and demolition

Council has the authority under the Environmental Planning and Assessment Act 1979 to issue stop-work orders and, where unapproved works cannot be rectified, demolition orders.

A structure build in good faith as exempt development that turns out not to qualify can be subject to mandatory removal at the owner's cost.

This outcome is not hypothetical. It happens and it applies to structures that look entirely ordinary, including decks and carports that simply sit in the wrong zone or exceed a dimension threshold.

Property sale complications

Section 10.7 planning certificates issued on sale disclose planning constraints and development history. Building inspectors conducting pre-purchase inspections identify unapproved structures .

A deck or garage conversion built without the approval the site required can delay settlement, reduce the sale price, or cause a contract to fall through entirely while the owner scrambles to regularise the works through a Building Information Certificate or a retrospective DA.

Insurance exposure

Home insurance policies commonly exclude damage to or caused by structures that were built without the required approval.

A carport that was not properly authorised and subsequently collapses or causes damage may not be covered.

The financial exposure sits with the homeowner, not with the builder who constructed it.

What a PPA Covers for Residential Works

A PPA for proposed works such as a deck, carport, pergola or garage conversion addresses each of the relevant variables before the first call to a builder is made.

• Confirmation of the applicable LEP and any heritage listings or conservation area designations applying to the land

• Bushfire prone land status and any implications for materials or pathway eligibility

• Flood overlay status and any flood control lot restrictions

• Review of the specific Codes SEPP standards for the proposed work type, including size, height, setback and material requirements

• Assessment of whether the proposed works qualify as exempt development, complying development requiring a CDC, or development requiring a full DA to council

• Where a DA is required, identification of supporting documentation and likely council fees and timeframes

• Where complying development applies, clarification of the private certifier process and the 20-business-day assessment period

Exempt, Complying or DA: A Practical Comparison

Proposed Work	Potentially Exempt	May Require CDC	Likely Requires DA
Deck under 25sqm, under 1m height, standard lot	Yes	No	No
Deck in heritage conservation area, front of building line	No	Possibly	Possibly
Carport, two or more sides open, under setback thresholds	Yes	No	No
Carport on bushfire prone land, within 5m of dwelling	No	Check materials	Possibly
Detached garage under 20sqm, 900mm setback	Yes	No	No
Detached garage over 20sqm	No	Possibly	Possibly
Garage conversion to habitable space	No	No	Yes
Any structure on heritage listed land	No	No	Yes
Any structure on flood control lot	Check	Check	Possibly

Check Before You Build

The exempt development pathway exists to reduce unnecessary regulation for genuinely minor works. It is a useful and well used pathway , and many decks, carports and pergolas in NSW are lawfully built under it every year.

But the pathway is conditional, not general, and the conditions are site-specific.

The cost of a Preliminary Planning Assessment before works commence is a fraction of the cost of rectifying unapproved works after the fact, whether that means engaging a certifier retrospectively, preparing a Building Information Certificate application, commissioning a DA for works already built, or in the worst cases demolishing a structure at your own expense.

Knowing your pathway before you build is not over caution. It is the straightforward way to protect your investment and make sure the project you have planned is actually the project you are allowed to build.

Not sure whether your project needs approval?

StraightLine Planning provides Preliminary Planning Assessments for homeowners across NSW. We confirm your approval pathway, flag any site constraints, and give you clear advice on what your project requires before you commit to a builder or a design.