The 1960s to 1980s double-brick home is Perth’s defining housing type. Two full skins of masonry with a cavity between, a concrete slab or timber floor, a tiled roof, aluminium windows, and a floor plan divided into small rooms serving a way of living that has largely disappeared.
For more detail on this part of the project, see What Is the Best Flooring for a Concrete Slab?.
They were built well. Double brick was adopted in Perth for sound reasons — sandy soils, a hot dry climate that rewards thermal mass, and termite pressure that punishes timber. Fifty years on, these houses are structurally sound, largely termite-proof in their walls, and sitting on blocks that are frequently larger than anything being subdivided today.
They are also dark, compartmentalised, uninsulated and disconnected from the outdoors. This guide covers how to fix that, what it costs, and the specific things double brick demands that timber-framed construction does not.
Understanding What You Have Bought
A typical Perth double-brick home is two skins of brickwork — an outer leaf and an inner leaf — separated by a cavity of around 50mm, tied together with wall ties, sitting on a strip footing or a slab. The roof is usually timber-framed with terracotta or concrete tiles. Windows are aluminium framed, single glazed.
The characteristics that govern every decision:
- The inner leaf is frequently load-bearing. Internal walls are not partitions; many of them are holding the roof up.
- There is no wall cavity for services. The cavity between the leaves is a moisture barrier, not a service void. Every wire and pipe must be chased in, bulkheaded, or run through the ceiling.
- The walls have thermal mass but no insulation. They store heat well and release it slowly, which in Perth’s climate is a mixed blessing: pleasant in a mild spring, punishing in a February heatwave when the house has been absorbing heat for a week.
- The cavity is an insulation opportunity. It can be injected, and this is the single most cost-effective thermal improvement available in these homes.
- Masonry is heavy. Demolition generates tonnage, disposal is priced by weight, and the work is slower and dustier than timber.
- The building is durable. Absent water ingress, a well-built Perth double-brick home has a very long life ahead of it.
Opening Up the Floor Plan
This is the defining renovation of these houses and the one that transforms them.
What it involves
Removing an internal double-brick wall is a structural engineering exercise, not a demolition one.
- Engineering assessment to determine what the wall carries and how the load will be transferred
- Steel beam design — an RSJ or similar sized for the masonry and roof load above
- Bearing points — piers, pads or engineered supports beneath each end of the beam, which frequently means breaking into the slab
- Temporary propping — acrow props and needling to hold the structure while the wall comes out
- Brick-by-brick removal, which is slow and generates enormous dust
- Beam installation and packing to ensure the load transfers properly
- Making good — the beam is usually concealed within the ceiling line or expressed deliberately, and the junctions require careful finishing
- Building permit — structural work requires one, with a certified application being the faster route
What it costs
A significant opening in a Perth double-brick home runs $8,000 to $18,000, and more where the span is long, the load includes a second storey, or the bearing points require substantial underpinning.
To put that in context: removing a load-bearing brick wall typically costs 20 to 30 per cent more than modifying a timber-stud wall of the same span. Owners moving from the eastern states routinely underestimate this.
Design decisions worth making
- Consider a wide opening rather than full removal. Retaining a nib of wall at each end reduces the span, reduces the beam size, and can significantly reduce cost while achieving most of the visual effect.
- Decide early whether the beam is concealed or expressed. Concealing it within the ceiling line requires more structural depth and coordination; expressing it as a deliberate element is cheaper and can look considered.
- Combine openings. If two walls are coming out, designing them together frequently allows a shared structural solution.
- Check what is above. A single-storey house with a lightweight tiled roof is one problem; a two-storey house with masonry above is a much larger one.
Services: The Real Constraint
The second double-brick reality, and the one that shapes what is affordable.
Electrical
Adding power points, data, lighting circuits or a new switchboard means chasing channels into solid brick, laying conduit, and making good the wall afterwards. It is slower, dustier and more expensive than the equivalent work in a framed house.
Practical approaches:
- Do it all at once. If the walls are being opened for any reason, run everything you might want — additional outlets, data, provision for future solar and EV charging.
- Use the ceiling. Running horizontally through the roof space and dropping down is often cheaper than chasing long horizontal runs.
- Consider surface-mounted solutions in secondary spaces such as a garage or workshop, where appearance matters less.
- Budget $3,000 to $9,000 for a switchboard upgrade and partial rewire, and $15,000 to $30,000 for a full rewire of a double-brick home.
Plumbing
In a slab-on-ground double-brick home, waste pipes are cast into or run beneath the slab, and supply runs are chased or run through the roof space. Relocating a bathroom or kitchen sink is genuinely expensive here — core drilling the slab, establishing new falls, and sometimes a step or bulkhead.
The design implication: in Perth, keep wet areas near their existing positions wherever the layout permits. The money saved is substantial and it buys finishes that people can actually see.
Air conditioning
Ducted systems in double-brick homes generally run through the roof space with ceiling outlets, which works well. Split systems require careful planning for pipe routes and condenser positions. Either way, decide the system before the ceilings are closed up.
The Cavity Insulation Opportunity
Unrenovated Perth double-brick homes almost universally have no wall insulation. The cavity between the leaves can be injected with foam or fibre insulation, substantially improving the wall’s thermal performance without altering the appearance in any way.
Why this matters in Perth specifically:
- Perth summers deliver extended runs above 35 degrees, and an uninsulated masonry wall absorbs that heat all day and releases it into the house all night
- The thermal mass that makes these houses pleasant in spring works against you in a heatwave without insulation to break the path
- The improvement is invisible, permanent and does not affect the building’s character or approval status
- It is far cheaper than any glazing upgrade and generally delivers more
Points to check before proceeding: the cavity must be clear of debris and mortar snots, the wall ties must be sound, and there must be no existing damp issue — injecting insulation into a wall with a moisture problem makes the moisture problem worse. A competent installer will inspect with a borescope first.
Windows, Openings and Shading
Enlarging openings
Making a window bigger, or converting a window to a door opening onto an alfresco area, requires a new lintel and brick-by-brick removal. Two complications:
- Brick matching. Original bricks from a 1970s home are frequently unavailable. Options are secondhand demolition bricks, which rarely match exactly, or rendering the elevation to conceal the transition.
- Lintel sizing. The wider the opening, the heavier the lintel and the more substantial the bearing.
Budget $3,500 to $12,000 per opening depending on size and whether rendering follows. Where several openings are being changed on one elevation, rendering the whole elevation is often the more coherent and sometimes the cheaper answer.
Shading beats glazing
In Perth’s hot dry climate, external shading stops solar heat before it reaches the glass and outperforms any window upgrade for a fraction of the cost.
- Wide eaves — many 1970s Perth homes have generous eaves already, which is worth preserving
- External awnings and blinds — $600 to $3,500 per window
- Adjustable external louvres — particularly effective on west elevations, which in Perth take a punishing afternoon sun
- Pergolas and planting
- A covered alfresco on the west or north-west, which shades the wall as well as creating living space
Roofs, Ceilings and Heat
Roof heat gain is the dominant summer load in a Perth home, and these houses were built with minimal or no ceiling insulation.
- Ceiling insulation to R5.0 or higher — $25 to $50 per square metre, and the single highest-value comfort measure available
- Roof space ventilation — eave intake with ridge or high-level exhaust. A Perth roof cavity can exceed 60 degrees on a summer afternoon.
- Reflective sarking when re-roofing — free to include at that moment, expensive to retrofit
- Roof colour — a genuine performance decision in this climate, free at the point of specification
- Re-bedding and re-pointing a tile roof — $4,000 to $12,000, and it extends roof life significantly. Perth’s tile roofs commonly need this at around 25 years.
The Alfresco Connection
The other transformative move on these houses. A 1970s Perth home typically has a small back door onto a patch of lawn, with no relationship between inside and out.
Opening the rear living area with a wide sliding or stacking door onto a covered alfresco area changes how the house is used for most of the year. Cost: $25,000 to $75,000 for the alfresco, plus $6,000 to $14,000 for the opening including lintel and making good.
Orientation matters. In Perth the afternoon sun from the west is intense and the sea breeze — the Fremantle Doctor — arrives from the south-west on summer afternoons. An alfresco positioned and screened to catch the breeze while shading the western sun is comfortable; one that does the reverse is not. See our guide to Perth decks and alfresco areas.
Services Condition and Other Checks
- Electrical. 1970s wiring may lack safety switches and have an undersized board. Budget $3,000 to $9,000 for upgrade, more for a full rewire.
- Plumbing. Galvanised steel supply pipe in older homes corrodes internally. Replacement in a double-brick slab home is disruptive — $10,000 to $22,000.
- Asbestos. Common in eaves, wet area sheeting, fencing and vinyl backing in homes from this era. $2,500 to $15,000.
- Roof framing. Timber, and therefore the one part of the house termites can reach. Have it inspected.
- Damp. Check for rising damp at the base of walls, bridged cavities where mortar has fallen, and blocked weep holes. Weep holes must be kept clear — they are how the cavity drains.
- Wall ties. In coastal suburbs, older wall ties can corrode. Signs include horizontal cracking at regular intervals up the wall.
Budget and Sequence
A full renovation of a 1970s Perth double-brick home — opened floor plan, new kitchen and two bathrooms, rewired, cavity insulated, ceiling insulated, new flooring throughout, and a covered alfresco — costs $200,000 to $420,000 and takes eight to sixteen months from first design to completion.
The order that avoids waste:
- Investigate. Building inspection, timber pest inspection, structural engineer’s view on the walls you want to remove, and a borescope check of the cavity. $2,500 to $5,000 that changes what you design.
- Fix the water. Roof, gutters, downpipes, weep holes and any damp issue. Injecting insulation into a damp cavity makes things worse.
- Structure. Wall removal, steel, and any opening changes.
- Services. All electrical and plumbing while walls are open and chased.
- Insulation. Cavity injection and ceiling insulation.
- Wet areas.
- Kitchen and finishes.
- Alfresco and landscaping.
These houses reward owners who work with the construction rather than against it. The ones that feel wonderful afterwards are not the ones where every wall came out regardless of cost — they are the ones where the right two walls came out, the cavity was insulated, the roof was dealt with, and the back of the house finally opened onto somewhere worth sitting.
Damp: The Problem to Diagnose First
Perth’s characteristic masonry problem, and the one that must be resolved before any finishing work.
Salt damp
Presents as blown render, salt crystallisation and deteriorating brickwork at the base of walls. Causes in Perth homes:
- External ground or paving levels raised above the damp course over decades
- Reticulation spraying against the wall on every cycle
- Blocked weep holes, so the cavity cannot drain
- Garden beds built against the brickwork
- A concrete path or patio slab poured hard against the house
Correct treatment sequence: lower ground levels below the damp course, move the reticulation, clear or reinstate the weep holes, remove impermeable render from affected areas, install a chemical damp course by injection where none exists, allow the wall to dry — which takes months — and only then apply a breathable finish.
A related guide to consider while planning this work is Rising Damp in Older Homes: Diagnosis and Treatment Options.
Never seal a salt-damp wall with impermeable render or paint. It drives the moisture higher and makes the problem worse.
Corroded wall ties
In cavity construction near the coast, the metal ties connecting the two brick leaves corrode. As they rust they expand, lifting the brickwork and producing horizontal cracking at regular intervals up the wall — typically every fourth or fifth course.
This is a structural issue, not cosmetic. Remediation involves installing replacement ties, which is expensive and disruptive. It is also a reason to be cautious about injecting cavity insulation without a borescope inspection first.
Roofs and the Terracotta Problem
Most 1970s Perth homes have terracotta or concrete tile roofs, and they reach a predictable maintenance point at around 25 years.
- Re-bedding and re-pointing ridges and hips — $4,000 to $12,000, and it extends roof life significantly
- Tile matching is genuinely difficult in Perth, where many profiles are discontinued. Salvage yards are the usual source, and sourcing should be resolved before any partial roof work begins.
- Full re-roof — $100 to $190 per square metre. This is the moment to add reflective sarking and choose a light colour, both of which are near-free at that point and expensive later.
- Roof space ventilation — install it while the roofer is on site
A Realistic Sequence and Budget
A full renovation of a 1970s Perth double-brick home — opened floor plan, new kitchen and two bathrooms, rewired, cavity insulated, ceiling insulated, re-roofed with a light colour and sarking, new flooring throughout, and a covered alfresco — costs $200,000 to $420,000 and takes eight to sixteen months from first design to completion.
The order that avoids waste:
- Investigate. Building inspection, timber pest inspection, structural engineer’s assessment of the walls you want to remove, salt damp and wall tie check, and a borescope look at the cavity.
- Fix the moisture. Ground levels, reticulation, weep holes, roof, gutters and soakwells. Everything downstream depends on the walls being dry.
- Structure. All wall removals and new openings in one campaign, because propping and engineering are expensive to mobilise twice.
- Services. All electrical and plumbing while walls are chased open.
- Thermal envelope. Cavity insulation, ceiling insulation, roof ventilation, external shading.
- Wet areas.
- Kitchen and finishes.
- Alfresco and landscaping.
The single most important sequencing point is doing all the structural work at once. Mobilising an engineer, propping and a bricklayer twice costs far more than doing it once — so if two walls are eventually coming out, take them both out in the same campaign even if the second room stays unfinished for a year.