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How SHM transformed a cold, leaky mid-century double brick home in Coburg North into a comfortable 4-bedroom sustainable family home.
There's a type of home you find all across Melbourne's inner north that we genuinely love to work on. The mid-century double brick. Solid as anything. Full of character. And usually, absolutely freezing in winter and an oven in summer.
This one, a cream clinker brick home in Coburg North near the beautiful parklands of Merri Creek, was no exception. Blustery as all buggery, to put it plainly. A pre-renovation blower door test recorded a whopping 27.7 air changes per hour at 50 Pascals. For context, the NCC target is under 10ACH. The NatHERS star rating came in at a miserable 3.1 stars, against an Australian average that's already a pretty grim 1.8 stars.
This home was leaking like a sieve.
A young family, an environmentally conscious couple with two toddlers who love their Coburg North community, their proximity to Merri Creek, and their local schools, asked us to turn it into something they could live in happily for the rest of their lives.
We got it to 6.1 NatHERS stars and 7.4 ACH. While keeping over 90% of the original structure.
Here's how.
Before we talk about the challenges, it's worth saying clearly: this was a home worth fighting for.
It sat on the corner of a quiet cul-de-sac with a genuinely welcoming street presence. The cream clinker brickwork had the lovely charm of Melbourne's early post-war heritage, that slightly handmade quality you just can't replicate with modern materials. The slimline steel windows, original to the 1950s, gave lovely views of the garden with a minimalist character that's become sought after again. The foundations were in excellent condition. And its position near Merri Creek made it the kind of inner-north Melbourne property that, once improved, would be a genuinely exceptional place to raise a family.
Our clients weren't looking to sell and move somewhere easier. They wanted to stay in their community, in their home, and make it work properly. That's the brief we love.
Let us be upfront about what we were dealing with, because these are the exact challenges that put a lot of people off renovating Melbourne's mid-century housing stock.
Orientation. North to the front is the most challenging orientation for passive solar design. The main living spaces face the wrong way. It limits what you can achieve through orientation alone, which means the building fabric has to work harder.
Double brick walls with no insulation. This is the characteristic challenge of Melbourne's post-war housing. The walls themselves have essentially zero insulation value. A lot of people talk about blowing insulation into the cavity, but with double brick, if there even is a cavity, it's typically far too tight for any useful result. You need a different solution.
Single-glazed steel windows. As much as we love their aesthetic character, original single-glazed steel windows are a major source of heat loss. The complication here was that the 1950s installers had welded these frames directly to the steel lintels above. Replacing them outright wasn't an option.
Barely any insulation anywhere. Some remnants in the ceiling. Nothing under the floor. Nothing in the walls.
Starting at 27.7 ACH tells the full story. This home was essentially open to the weather.
The brief was clear. Transform a cold, leaky 2-bedroom, 1-bathroom home into a comfortable, sustainable forever home for a growing family, without leaving the neighbourhood they love.
The result needed to be 4 bedrooms and 2 bathrooms. It needed to feel spacious but not wasteful. And it needed to perform to a standard that would make living in it a genuine pleasure through Melbourne's cold winters and hot summers.
What the home also needed, and this was our addition, was a considered approach to the street. The corner position was an opportunity to do something interesting with the facade. We weren't going to waste it.
We designed a two-storey extension to the south, deliberately contained to a limited footprint. This kept the demolition plan minimal, which mattered both for budget and for embodied carbon. We kept nearly all of the existing brick walls intact.
A few things about the extension deserve particular mention.
The staircase connecting the ground and first floors is zoned on the west side of the home, and also connects to the living room and what we called the European terrace. We know open-plan staircases look great in magazines, but they are genuinely terrible for thermal comfort and energy efficiency in Melbourne's climate. Hot air rises straight up. A zoned staircase keeps the thermal zones of the home working properly.
The first-floor extension also includes a daybed area positioned to capture city views and the nightly bat migration over Merri Creek, and the kids are obsessed with it. And in place of the original rooftop bath, we installed a green roof.
The corner position gave us the opportunity to address the street frontage with something genuinely interesting, which we'll come back to. The major renovation works on the existing home focused on the kitchen, bathroom, and laundry.
The result: a 4-bedroom, 2-bathroom family home. Brief nailed.
For the new extension, we used our standard 140mm stud wall system with a ventilated cavity. The cladding is zinc corrugated iron: durable, zero-maintenance, and self-shading. The ripples in the material ensure no part of the surface is in full direct sun, which matters for both thermal performance and longevity. We still installed our counter batten system for a proper ventilated cavity.
We also applied beautiful western red cedar shingles to the facade, a material we never get tired of working with. The first-floor ceilings were kept pitched to promote natural cooling. Hot air rises, and pitched ceilings give it somewhere to go.
For the extension's roof and wall system: R6.0 ceiling batts, ProClima Mento as our roof weather-resistant barrier, and Rylock double-glazed thermally broken aluminium windows throughout.
Double brick walls with no insulation. This was the central challenge of the renovation.
The solution we went with was applying 60mm Kingspan K17 Kooltherm insulated plasterboard internally to all external walls. This achieves a respectful R2.35 insulation value, a genuine transformation from effectively zero R value. Going from no insulation to R2.35 on a double brick wall is not a small thing. That is the single most impactful upgrade you can make to this type of Melbourne home.
Our original intention for the single-glazed steel windows was straightforward: remove them, get a custom measure from Rylock, and replace them with thermally broken double-glazed aluminium windows. Simple.
It turned out the 1950s installers had other ideas. The frames were solid-welded to the steel lintels above. Replacement was off the cards.
So we took a different approach. We left the frames in place, removed the single-glazed units, and got the team at Quinn's Painting to sandblast the frames back and repaint them to match our new windows. Before we did any of that, we had the old glazing putty tested for asbestos, because the original method used putty in the same way as timber windows, and it frequently contained asbestos. Fortunately the test came back negative, and we were clear to proceed. We then installed double-glazed units into the restored frames.
The result: mid-century steel windows that retained all their original character and are now genuinely double-glazed.
Ceiling insulation was straightforward: R6.0 batts installed throughout, with any penetrating light fittings specified as IC-rated.
The underfloor was a little more involved. We had good height under the existing timber sub-floor, which gave us room to work. We removed the existing floorboards, found and straightened a few compromised bearers and joists while we were at it, and then installed R2.5 polyester batts. Chipboard went back down over the newly prepared sub-floor, topped with recycled Messmate flooring sourced from Timber Revival. A solid, well-sealed, beautiful floor.
Before renovation:
After renovation:
That last point matters. We didn't knock this home down and start again. We worked with what was there: the double brick, the clinker character, the steel windows, the foundations, and brought it up to a standard that most new construction in Australia doesn't reach.
That is what a well-executed renovation of Melbourne's mid-century housing stock looks like.
There are thousands of homes like this one across Coburg, Brunswick, Northcote, Ivanhoe and the broader inner north. Mid-century double brick. South-facing. No insulation. Single glazing. Cold, expensive to run, and genuinely uncomfortable.
Most of their owners don't realise what's possible. They assume that the double brick is too hard, that the orientation can't be overcome, that the steel windows can't be improved. This project shows that none of that is true.
With the right team, the right approach, and a clear brief, you can take a 3.1-star, 27.7 ACH double brick home in Coburg North and make it a 6.1-star, 7.4 ACH sustainable family home, while keeping the cream clinker, the steel windows, the neighbourhood character, and almost every brick of the original structure.
A huge thank you to our wonderful clients for the trust they placed in us and for allowing us to create something genuinely meaningful in their home. And to the full SHM design and build team who pulled this one together.
This is what's possible. We hope it's useful to anyone in Melbourne sitting in a cold, draughty mid-century home wondering whether it's worth the effort.
It absolutely is.
