Design Considerations / Comfort & Energy / Construction & materials
Construction
Brick veneer, double brick, timber frame, insulated panels, rammed earth: every system can make a good house in Canberra, and every one can make a poor one. What matters is where the insulation sits, where the mass sits, and how carefully the pieces are joined.
Design ConsiderationsComfort & EnergyAt a glance
Any construction system can work in Canberra if the insulation is continuous, the shell is airtight, and the heavy materials sit inside the insulation where the winter sun can reach them. Choose the system with embodied carbon and the bushfire rating in mind, and draw the junctions carefully.
- Brick veneer puts the brick outside the insulation, where it does little thermally. Reverse brick veneer puts it inside, where it stores warmth.
- Uninsulated double brick is too cold for Canberra winters. Insulate the cavity.
- Lightweight frames and insulated panels work well with high insulation and airtightness. Add mass where the sun falls.
- In year-long testing, insulated heavy walls kept rooms comfortable more of the time than insulation alone.
- Leave sunlit floors uncovered so the slab can store heat, and insulate the slab edges.
- Concrete and steel carry high embodied emissions. NSW's BASIX now measures them.
- On bushfire-prone blocks, the required Bushfire Attack Level shapes the glazing, cladding and decks. Find it out first.
The optionsCommon wall systems compared
The question for any wall is which side of the insulation the heavy material sits on. Mass inside the insulation stores the room's warmth. Mass outside it mostly stores the weather.
| System | Layers, outside to in | Thermal behaviour | In Canberra |
|---|---|---|---|
| Brick veneer | Brick, cavity, insulated frame, plasterboard | The brick is outside the insulation, so it adds weatherproofing and durability but little useful mass | Works well if the frame is well insulated. The most common system. |
| Reverse brick veneer | Lightweight cladding, insulated frame, brick | Brick on the inside stores sun and heating warmth | Very good, especially in sunlit living areas |
| Cavity (double) brick | Brick, cavity, brick | Mass on both sides, with little insulation unless it's added | Needs cavity insulation. Uninsulated, it is too cold in winter. |
| Lightweight frame | Cladding on battens over a ventilated cavity, insulated timber or steel frame, plasterboard | Little mass, so it warms and cools quickly | Good with high insulation and airtightness. Pair it with a slab or internal mass where the sun reaches. |
| Insulated panels (SIPs) | Board, rigid foam core, board | High insulation, very airtight, little mass | Very good shell. Plan the mass elsewhere. |
| Rammed earth or mud brick | Solid earth wall | Very heavy but a poor insulator on its own | Needs an insulated core or insulated cladding for Canberra winters |
No single system wins everywhere. The best Canberra houses usually combine a well-insulated, airtight outer shell with some heavy material inside it, placed where the winter sun reaches.
The evidenceWhat full-scale testing found
Over several years, researchers in Newcastle built full-size test rooms with different walls and monitored them through a whole year, with no heating or cooling. The share of time each room stayed between 18 and 24°C:
| Wall system | Time between 18 and 24°C |
|---|---|
| Insulated cavity brick | 62% |
| Insulated lightweight frame | 55% |
| Insulated brick veneer | 54% |
| Uninsulated cavity brick | 52% |
| Outside air, for comparison | 31% |
Insulated brick veneer was the best of the four in cold weather. Insulated cavity brick was the best in hot weather and the best overall. The researchers concluded that a wall's R-value doesn't tell the whole story. Thermal mass combined with insulation outperformed high insulation without mass.
Newcastle's climate is milder than Canberra's, so the ranking would shift here towards the systems that keep heat in. The lesson holds: insulation and mass together beat either one alone.
03 / Floors and roofs
Floors. A concrete slab on the ground is the most common Canberra floor, and it's useful mass if winter sun falls on it and its edges are insulated. Covering it in carpet or timber throughout gives most of that away, so leave sunlit areas as tiles, polished concrete or stone. A suspended timber floor has little mass and must be insulated and sealed underneath. It suits steep sites, flood or root zones, and rooms that need to warm up quickly.
Roofs. In winter the ceiling insulation does the work. In summer the roof colour matters too. A pale roof reflects much more of the sun than a dark one, and the code allows less ceiling insulation under a light-coloured roof in some cases. In Canberra, a mid-to-light roof with a ventilated roof space is a sensible default. Very dark roofs make summer bedrooms harder to keep cool.
What it took to reach ten stars
One NSW house in the Hunter Valley started at 9.2 stars and reached the maximum 10. It used reverse brick veneer outside, single brick internal walls for mass, 600 mm eaves on the north and west, a living area widened to face north, smaller windows than first drawn, and an adjustable louvre roof over the patio. Its designer said no single change got it there: it took 20 or more small ones, each checked against both heating and cooling. Construction choices matter, but they work alongside everything else.
Embodied carbonThe emissions built in before you move in
Every material carries emissions from being made and transported. In 2019 these embodied emissions were about 16% of the built environment's carbon footprint in Australia. Over the years to 2050, the upfront emissions of new construction are expected to make up around half of its footprint, as operating energy gets cleaner.
NSW now measures this. Since October 2023, BASIX includes a Materials Index that calculates the embodied emissions of a new home's floors, walls, roof and glazing. There's no target yet, and the score is for information only, but the materials chosen become commitments on the BASIX certificate.
The main ways to lower it:
- Use less concrete and steel, two of the most emissions-intensive materials in a typical house. That might mean a smaller slab, or timber framing instead of steel.
- Choose lower-carbon versions where heavy materials are needed, such as concrete with supplementary cementitious materials, or recycled bricks.
- Build smaller and simpler. Less house means less material.
BushfireWhen the block is in a bushfire-prone area
Much of Canberra's urban edge, and the rural land around it, is bushfire-prone. On an identified bushfire-prone block, the house, any carport or garage, and attached decks must be built to the Bushfire Attack Level (BAL) set for the site under Australian Standard AS 3959. The required level comes from the planning instruments or from a site-specific assessment by a bushfire consultant.
A BAL affects construction choices well beyond appearance: the type of glazing and frames, the cladding and its sealing, ember guards on vents and weepholes, decking materials, and roof edges. Higher levels rule out some systems altogether. Establish the BAL before choosing the construction system, not after the windows have been selected.
In NSW, bushfire-prone land is mapped by councils and assessed under Planning for Bushfire Protection, with the same Australian Standard for construction.
QualityBuilding it well
The best system performs badly if it's poorly put together. The weak points are the joins:
- Where walls meet the roof and the floor. Insulation and air barriers have to run continuously around these corners.
- Around windows and doors. Frames need sealing to the wall, and wraps need taping into the openings.
- Where services pass through. Every pipe, cable and duct makes a hole in the air barrier.
- Where materials change. A steel beam running from inside to outside, or a slab extending to an outdoor terrace, carries heat across the insulated line.
These junctions are drawing work. A wall section on a drawing should show how the insulation, membranes and air barrier continue around every corner, so the builder isn't left to improvise. See Condensation and building breathability for the cavities and membranes now required behind cladding in Canberra. Substitutions during construction, such as a different wrap, a cheaper batt or a different window, should be checked against the energy certificate before they're accepted.
Applying it locallyCanberra and New South Wales
Canberra and the Southern Tablelands. Winter heat loss and condensation at cold junctions are the main risks. Choose a well-insulated, airtight shell and put the mass inside it, where the winter sun can reach it.
Alpine areas. Insulation and airtightness come first. Mass helps only where it gets direct sun, and snow loads and freeze-thaw shape the roof and cladding choices.
The NSW coast. Lightweight, well-shaded, well-ventilated construction often suits, and salt exposure and wind-driven rain govern the cladding and fixings.
Western plains. Large day-to-night swings favour heavy construction inside an insulated shell, cooled overnight.