Australian houses are drawn in millimetres, wear a single skin of brick, and keep their structure hidden inside a timber frame. That combination - the brick veneer - is the detail that most quietly reorganises a project, because it looks like masonry country from the street and behaves like frame country the moment you drill into it. Add a concrete slab, a steel or tiled roof, and a rulebook that takes bushfire and termites as seriously as drainage, and the imported renovation guide starts misfiring in specific, predictable ways.
This guide covers the conventions that change planning most: how drawings and materials are measured, how the veneer wall actually works, what the NCC says about rooms and ceilings, and how bushfire and termite rules shape the build. Practice varies by state, builder and era - everything here is typical, not universal.
Australian plans and trades work in metric: dimensions in millimetres, materials in square metres and cubic metres. The typical detached house is brick veneer - one skin of 230 × 110 × 76 mm bricks (roughly 48–50 per m²) over a timber frame per AS 1684, on a concrete slab. Roofs: profiled steel sheet (Colorbond and rivals) or concrete tiles. The NCC sets 2.4 m habitable ceiling minimums (2.1 m kitchens/bathrooms), sorts the country into eight climate zones, and drives bushfire BAL ratings (AS 3959) and termite management (AS 3660). Supply is 230 V; fixed wiring is licensed-electrician work.
The Drawing Speaks Millimetres
Like South African and continental European practice, Australian working drawings dimension everything in millimetres: a room is 3600, a ceiling 2400, a door 2040 high. The unit is understood, never written. Frame spacing follows the same tidy module - wall studs and roof members commonly at 450 or 600 centres, which is why plasterboard sheets, lining boards and insulation batts all arrive in widths that divide neatly into those numbers.
The consequence for imported advice is the usual one: convert before anything meets the plan. A 12 ft span is 3658 mm on paper - and the honest local version is 3600 or 3900, because the frame, the brick module and the sheet sizes all prefer the rounded numbers the local supply chain actually stocks.
Brick Veneer: Brick Outside, Timber Inside
The dominant Australian detached house is not masonry in the structural sense - it is a timber-framed building wearing one skin of clay bricks. The frame, erected first, carries the roof and the floors; the bricks go up outside it, tied back with wall ties across a roughly 40–50 mm cavity, serving as cladding and weathering, not structure. Timber framing follows AS 1684; steel framing is the common alternative and quietly solves the termite question that follows below.
Veneer reshapes DIY planning in three practical ways. Hanging anything heavier than a picture means finding a stud behind plasterboard, not plugging into brick - a wall that resists a nail everywhere is the double-brick house, not this one. Renovations open framed walls with a saw rather than chasing channels out of masonry. And the wall's thermal performance lives almost entirely in the frame's insulation, because a 110 mm brick skin neither insulates nor needs to. The brick counts, though, are real arithmetic: a single-skin veneer of standard bricks runs roughly 48–50 per square metre of wall face - about half the demand of the double-brick builds described in the South African guide - and the Brick & Block Calculator runs that count from any unit size.
Slab on the Ground
New detached homes overwhelmingly sit on concrete slabs, and on the reactive clay soils common across the continent the slab is usually an engineered raft - historically the waffle raft, with its grid of stiffening beams, though practice has shifted between waffle and conventional edge-beam designs as soil-assessment thinking evolves. For the home planner, the slab carries three consequences. Plumbing and electrical positions are effectively fixed at pour time: moving a drain later means concrete surgery. The slab edge is part of the termite-inspection regime and should stay visible, not buried under garden beds. And floor levels are set to the slab's finished height, which is the number your decking, tiling and paving all want to meet.
Roofs: Sheet Steel and Concrete Tiles
Two traditions share the rooftop. Profiled steel sheet - sold under the brand name that became the generic, Colorbond - is the lighter, lower-maintenance covering, fixed with screws and sealing washers over sarking and battens, and tolerant of the lower pitches that suit wide eaves. Corrugated runs 762 mm cover per sheet as it does in South Africa; trapezoidal profiles offer similar cover with a squarer shoulder. Concrete and terracotta tiles are the other tradition: heavier, laid over battens with under-tile membrane, profiled and colour-fixed regionally, and wanting a steeper pitch to shed water reliably.
Roof framing is overwhelmingly prefabricated timber trusses, which is the renovation-planner's warning: attic conversions and removed walls under a trussed roof are structural conversations, not weekend demolitions. The Roofing Materials Calculator handles the covering arithmetic - sheet counts by cover width, tile counts per square metre - for either tradition.
Ceilings, Rooms and the NCC
The National Construction Code is the national rulebook, and its room-height numbers are worth knowing verbatim: 2.4 m minimum in habitable rooms, and 2.1 m in kitchens, bathrooms, laundries, corridors and garages. Those are legal floors rather than design targets - new builds commonly order 2.55–2.7 m or higher ceilings as a standard upgrade - but they explain why the classic Australian reno finds 2.4 m plaster ceilings on framing that happily accepts downlights, ceiling fans and the rest of the low-profile arsenal.
Eight Climate Zones
The NCC divides the continent into eight climate zones, running from steamy tropical zone 1 across the arid interior to the alpine zone 8 of the high country, and the zone number quietly drives the insulation requirements, glazing expectations and ventilation strategy of any new build or major renovation. A Darwin build and a Hobart build are different physics problems with different mandated answers. For the home planner, the practical translation: insulation quantities are zone-specific, not national, and the R-value on a product datasheet is zone-1-through-8 context. The Attic Insulation Calculator does its area-and-depth arithmetic in any units - mind the US-R versus metric-R distinction its guide covers - but how much insulation is enough is a zone question first.
Bushfire: BAL Ratings
In bushfire-prone areas - a substantial share of the continent's settlement - the site's Bushfire Attack Level decides a layer of construction rules under AS 3959. Six levels run from BAL-LOW through 12.5, 19, 29 and 40 to BAL-FZ, the flame zone, and each step tightens the requirements: ember-mesh screens, protected glazing, non-combustible wall and roof materials, sealed gaps and specific detailing. The levels tightened substantially after the 2009 Victorian bushfires reshaped the national rules. The BAL comes from a site assessment - slope, vegetation, distance to hazard - by a qualified assessor, and it is one of the first boxes to tick on any rural or peri-urban project, because it can redirect the whole materials plan.
Termites
Most of the Australian mainland is termite country, and building practice treats it that way as standard. New homes require a termite management system to AS 3660 - physical barriers built in during construction, chemical soil treatments, termite-resistant framing, or the steel-framed route that sidesteps the food source entirely - and the ownership side of the bargain is inspections: slab edges kept visible, annual professional checks, and the discipline of not stacking mulch or firewood against the house. For renovators, the surprise is usually a pleasant one: because the structure is frame, damage is localized and repairable rather than hidden inside load-bearing masonry.
Electricity and Water
Supply is 230 V at 50 Hz, with the flattened-pin plug that is unmistakably local. Fixed electrical work is licensed-electrician territory in every state, with compliance paperwork to match - the certificate names and rules vary by state, but the boundary is the familiar one: plug tops and unplugged appliances for the householder, anything fixed into the wiring for the professional. On the water side, rainwater tanks are a normal feature of Australian homes rather than a curiosity - feeding gardens, laundries and sometimes the whole house - with requirements varying by state and council over the years. The arithmetic is the universal one: 1 mm of rain on 1 m² of roof is a litre, and the Rainwater Collection Calculator runs the annual sum.
How This Site's Calculators Map to Australian Practice
Everything on this site is metric-first - millimetres in, square metres and litres out - which is the language Australian drawings and merchants already speak. Four tools map especially well:
- Brick & Block Calculator — single-skin counts for the veneer; the standard 230 × 110 × 76 mm brick at 10 mm joints slots straight in at roughly 48–50 per m².
- Roofing Materials Calculator — sheet and tile arithmetic for either roof tradition, including pitch multipliers and waste.
- Gutter & Downpipe Calculator — catchment area by pitch; Australian downpipe sizing is rainfall-intensity driven, exactly the calculator's logic.
- Rainwater Collection Calculator — the tank arithmetic from roof area and local annual rainfall.
The one place to read the fine print is structural timber: the deck calculator works from North American IRC span tables, and Australian framing sizes, grades and treatment levels follow their own standards - see Timber and Lumber Sizes Around the World before sizing anything structural.
Common Mistakes
- Assuming the brick is structure. It's cladding - anchors, shelves and TV mounts belong in studs, not mortar joints.
- Importing a double-brick plan. Veneer wants half the brick count and a frame that needs bracing, not mass.
- Ignoring the BAL step. In bushfire-prone areas, the site assessment can redirect the entire materials list - find the level before ordering.
- Burying the slab edge. Gardens against the slab hide the termite inspection edge the management system depends on.
- Planning a truss-roof attic conversion casually. Trusses are engineered; removing or cutting them is structural design work.
Plan It With the Brick & Block Calculator
A veneer wall carries one honest quantity: the count. Enter wall area and the standard brick at 10 mm joints, and the tools speak Australian units - millimetres in, bricks and pallets out. Run the Brick & Block Calculator for the skin, the Roofing Materials Calculator for the covering, and the Rainwater Collection Calculator for the tank.
Frequently Asked Questions
Is brick veneer the same as double brick?
No - and the difference reshapes almost every project. Double brick is structure: two skins of masonry carrying the loads, as in much South African and older British building. Brick veneer is cladding: one skin of bricks tied to a timber (or steel) frame that does all the structural work, with roughly a 40-50 mm cavity between. Consequences: hanging anything heavy means finding the studs behind plasterboard rather than plugging into brick; renovating means opening a framed wall rather than chasing masonry; and thermal behaviour follows the insulated frame, not the brick.
How many bricks per square metre in Australia?
The standard Australian brick is 230 x 110 x 76 mm; laid with 10 mm joints it covers about 0.0206 m2, so a wall runs roughly 48-50 bricks per square metre. Because a veneer is a single skin, a whole-house count is roughly half what the same house in double brick would demand. The Brick & Block Calculator runs the arithmetic from any unit and joint size.
What is a BAL rating?
A Bushfire Attack Level - the site's measured exposure under the Australian standard AS 3959. Six levels run from BAL-LOW through 12.5, 19, 29 and 40 up to BAL-FZ (flame zone), and each step raises the construction requirements: mesh screens, protected glazing, non-combustible cladding and roof detailing, sealed gaps. A site assessment by a qualified assessor sets the level in bushfire-prone areas, and the rules tightened substantially after the 2009 Victorian bushfires.
What is the minimum ceiling height in Australia?
The National Construction Code sets 2.4 m as the minimum for habitable rooms, and 2.1 m for kitchens, bathrooms, laundries, corridors and garages. Those are floors, not fashions - new builds commonly order 2.55-2.7 m or higher as an upgrade. As with all code numbers, treat this as the shape of the rule and confirm the current edition for your project.
Do Australian homes need termite protection?
In most mainland regions, yes - termites are a design assumption, not a regional surprise. New homes typically need a management system to AS 3660: physical barriers during construction, chemical soil treatments, termite-resistant materials or steel framing, plus the inspection regime that keeps the guarantee meaningful. Slab edges left visible for inspection, and regular professional checks, are part of normal ownership. The exact requirements vary by state and site.
Planning guidance only. NCC requirements, BAL assessments, termite rules and licensing vary by state and site - confirm the current rules for your project, and treat fixed electrical work as licensed-trade territory everywhere.
Related MyHouseLogic Guides
- Home Project Basics for South Africa — the double-brick contrast: two structural skins, 50 kg cement bags, IBR and tile roofs.
- Timber and Lumber Sizes Around the World — the regional mapping for structural timber, before the frame is sized.
- Tile Planning for UK Bathrooms — another metric-country walk-through, wet-room edition.
- Homes Around the World — the collection of regional measurement and planning guides.
- Field Guide library — every MyHouseLogic guide, each tied to a calculator.
The bottom line: Australian homes are metric, veneered and slab-based: plan in millimetres, hang on the studs not the brick skin, order one skin of 230 × 110 × 76 mm bricks at 48–50 per m², and clear the BAL and termite questions before the materials list. The brick is the coat; the frame is the body.