PERTHFire separation of roofed outdoor areas: the rule your patio may trigger
WA's fire-separation rule for roofed outdoor areas: WA H3D7 and Part 9.6 of the ABCB Housing Provisions, why alfrescos and patios near a boundary need
That alfresco or patio at the back of a modern Perth home, the roofed outdoor area everyone builds now, has a fire-safety rule attached to it that most owners never hear about. When it sits close to a boundary, it can need fire separation, and getting it wrong is the kind of thing that surfaces at the worst moment: during a sale, or after a neighbour's fire.
What a roofed outdoor area is
In the building rules, a roofed outdoor area covers verandahs, alfresco dining areas, balconies and the like, and it includes those uses when they sit below another part of the building, such as a ground-floor alfresco beneath an upper-floor balcony. If it has a roof and it is part of the dwelling, it counts, even though it is open on one or more sides.
These have become a standard feature of the modern WA house, often built right out toward the rear or side boundary to make the most of a block. That is exactly where the fire-separation question arises.
The rule, and where it lives
Western Australia has its own state-specific provision for this. Under the National Construction Code, WA H3D7 deals with the fire separation of roofed outdoor areas, and compliance with WA Part 9.6 of the ABCB Housing Provisions satisfies the fire-separation performance requirement. It is a WA variation, the roofed-outdoor-area rule is not something you will find explained on a generic national website, which is part of why it gets missed.
The principle behind it is the same one that governs any part of a house near a boundary: a fire in your building should not readily spread to the neighbour's, and vice versa. A roof over an outdoor area close to the boundary can carry fire along it, so where it sits within the trigger distance of a boundary, it needs fire-resisting construction, typically a fire-rated wall or cladding on the boundary side, and care with any openings underneath.
Why it matters to a buyer
Because a patio or alfresco added without regard to this rule is unauthorised or non-compliant work, and that is a problem to inherit. It can mean the structure was never properly approved, and resolving it after the fact can require bringing it up to standard or obtaining a building approval certificate for the unauthorised work, covered in our guide on building permits.
Alfresco and patio additions are among the most common owner-added structures on Perth homes, and among the most commonly done without a permit, because they feel like minor works. When they sit near a boundary, they are not minor, and the fire-separation rule is one of the reasons why.
What an inspection looks at
On a home with a roofed outdoor area near a boundary, we look at how it is built and whether the boundary side has the fire-resisting construction the location calls for, and we flag where an addition looks like it was built without approval, different construction from the main dwelling, no sign of proper connection or documentation. Under AS 4349.1 we report what is visible and recommend the permit history be checked with the local government, because whether a specific alfresco meets WA Part 9.6 is a compliance determination that turns on the exact boundary distance and construction.
A pre-purchase inspection catches the physical signs; confirming the approval is a records question worth resolving before you buy, particularly on a home where the outdoor area is a recent addition.
Why the rule exists at all
The requirement to fire-separate certain roofed outdoor areas can seem like an odd piece of red tape until you understand the risk it addresses, which is fire spread between buildings. The building code is concerned with stopping a fire in one building from spreading readily to the one next door, and a roofed outdoor area, a patio, a carport, an alfresco, changes the picture in a way that matters. A structure with a roof, even an open-sided one, close to a boundary can provide a path for fire to travel and can present a face to the neighbouring property that behaves differently from open ground. The rules about fire separation of these areas exist to manage that, by controlling how close to a boundary such a structure can be and what fire-resisting construction is required when it is close.
The reason this catches people out is that a patio or a carport feels like a minor, everyday addition, not the kind of thing that would trigger a serious building requirement. But a roofed structure built close to a boundary can, depending on its size, its position, and its construction, cross into territory where fire separation is required, and an owner or builder who did not realise that can end up with a structure that does not comply. The gap between how trivial the addition feels and how real the requirement is is exactly where the problem lives.
Where these structures go wrong
The situations that most often create a problem are the ones where a roofed outdoor area is added close to a boundary without the fire separation the code requires for that position. A large patio built hard against a side boundary. A carport at the line. A carport that runs to the boundary line. An alfresco under a main roof that extends the building toward a neighbour. Whether any of these actually triggers a fire-separation requirement depends on the specifics, the proximity to the boundary, the size, the construction, but the point is that these structures can trigger it, and they are frequently built by people who assumed a patio was just a patio.
Compounding this, roofed outdoor areas are among the additions most likely to be built without proper permits and approvals, precisely because they feel minor. An owner adds a patio, or a previous owner did, without a building permit, and nobody assessed whether it met the requirements, including fire separation where the position demanded it. The result is a structure that may not comply and that exists outside the approval record, which is a problem that surfaces when the property is sold, when someone wants to build near it, or when its non-compliance is noticed.
What it means for a buyer, and where an inspection helps
For a buyer, a roofed outdoor area close to a boundary is worth a second look, both because it may not comply with the fire-separation requirements and because it may have been built without approval. Unapproved building work is a liability that transfers with the property, and a structure that does not meet the fire-separation rules is work that may have to be modified or, in some cases, removed to be regularised. Neither is a reason for alarm by itself, patios and carports are added all the time, but both are reasons to establish the facts: was the structure approved, and does it comply, before assuming it is simply part of the house you are buying.
An inspection does not certify compliance with the building code, that is not what a building inspection is, but it can note where a roofed outdoor area sits close to a boundary in a way that raises the question, and where the construction or the position suggests fire separation may be in issue. Combined with confirming the approval record through your settlement agent, that flag is what turns a patio nobody thought about into a checked item. The broader lesson is the one that runs through so much of buying an established home: the additions that feel most minor, the patio, the carport, the alfresco, are often the ones built without approval and without regard to requirements like fire separation, They are worth checking. Everyone assumes they do not need it.
Common questions
Does my alfresco or patio need fire separation?
If it is a roofed outdoor area near a boundary, it can. WA H3D7 and Part 9.6 of the ABCB Housing Provisions govern fire separation of roofed outdoor areas — verandahs, alfrescos, balconies and the like — near a boundary.
Why is this a WA-specific rule?
The roofed-outdoor-area fire-separation provision is a Western Australian state variation in the NCC, which is why it is often missed — generic national guidance does not cover it.
What if a patio was built without considering it?
An alfresco or patio built without regard to the rule may be unauthorised or non-compliant work, which can require bringing it up to standard or obtaining a building approval certificate for the unauthorised work.
This comes up on every pre-purchase building inspection and building investigation & diagnostics we carry out.
Read next: combustible cladding: is it on the building you're buying into? and building permits in WA: BA1, BA2, and when you need one.
Sources
Read rather than recalled. Summarised here; the documents themselves are Crown copyright and are linked rather than reproduced.