A row of townhouses can share several walls and one long roof line. The building code makes sure a fire in one home does not race along the row into the next. Getting the fire separation right is one of the main things a certifier checks on any townhouse project.
Each townhouse is its own building
Under the National Construction Code, a townhouse is a Class 1a building when it is one of a group of attached dwellings, each separated by a fire-resisting wall. No home in the row may be stacked over or under another dwelling, or over or under a different class of building, apart from a private garage. A row built on top of a shared basement car park, for example, is generally Class 2 instead, and its certifier must hold a registration covering Class 2.
The separating walls
Part 9.3 of the ABCB Housing Provisions sets the rules for walls between Class 1 homes. In summary, each wall must:
- have a fire resistance level of at least 60/60/60, or be masonry at least 90 mm thick
- begin at the footings or ground slab
- carry on right up to the roof covering, with any gap filled with a fire-resisting material such as mineral fibre
- stay free of timber and other combustible elements crossing it, apart from small roof battens (75 x 50 mm or less) and sarking
On a long row, the details at the roof matter most. Where eaves, verandahs or similar spaces open into a roof space shared by more than one home, they need a non-combustible vertical lining at each separating wall line. Service openings in the walls must be limited in size and packed, and power points on opposite sides must be spaced apart.
External walls close to boundaries or other buildings
Part 9.2 of the Housing Provisions deals with external walls. It applies when a wall is closer than 900 mm to an allotment boundary (other than one facing a road), or less than 1.8 m from another building on the same lot. That second test often catches townhouse sites where two rows face each other across a narrow internal driveway.
A wall within those distances must:
- have an FRL of at least 60/60/60 when tested from outside, or be masonry or masonry veneer with at least 90 mm of masonry
- run from the footings to the underside of a non-combustible roof or eaves lining
- have its openings protected, for example with fixed fire windows or solid core self-closing doors, unless an exemption for small windows to bathrooms and laundries applies
Combustible fascias, gutters and downpipes also have minimum distances: 450 mm from a boundary and 900 mm from another building.
Smoke alarms in each home
Each townhouse needs smoke alarms on every storey, including the hallway serving bedrooms. Where a home has more than one alarm, they must be interconnected. In NSW, alarms in one townhouse do not need to be linked to the alarms next door.
Wall systems and evidence
Many townhouse projects use proprietary fire-rated wall systems. These must be built exactly as tested, and the certifier will ask for installer certification and product evidence before the occupation certificate. Plan for this paperwork from the start.
Fire separation details are easier to settle on paper than on site. Our plan assessment service can check the drawings, and our townhouses page explains how we certify these projects. When the frames are up, book the inspection at least 48 hours ahead through our inspection booking page.
Local help across NSW
CertifiBuild certifies Class 1 and Class 10 work in 39 council areas. Local rules on these council pages are a good place to start: Northern Beaches Council, Inner West Council, Canterbury-Bankstown Council, Hawkesbury City Council, Blacktown City Council, Waverley Council.
Suburb pages with local planning notes: Balgowlah, Balmain, Bass Hill, Bilpin, Blacktown, Bondi, Bondi Junction, Bonnyrigg, Bowenfels, Bowral. You can also browse every service area.
Sources
- Separating wall fire rules (Housing Provisions Part 9.3), ABCB
- External wall fire separation (Housing Provisions Part 9.2), ABCB
- Smoke alarm requirements for houses, ABCB Housing Provisions
- Guide to NCC building classes, ABCB