Castlemaine Cast and Block House
Proving Cast & Block at Scale with a High-Volume Builder Castlemaine, Victoria
Supplied by: Respirabuilt
Design Partner: Lifehouse Building Design
Builder: Regional Home Builders
Delivered on a steep site, this Castlemaine build had a few things working against it from the start. Given the slope, strong western sun, and the need to maintain construction progress at a standard pace, the project served as a valuable proving ground for the Cast & Block system.
For Respirabuilt, the project carried added weight. We worked alongside Regional Home Builders, delivering 60–70 homes per year, and Lifehouse Building Design, known for resolved, thoughtful residential work.
The project served as a proving ground for Respirabuilt Cast & Block system in a mainstream setting, with a standard crew, under real site pressures.
Ultimately, the real question wasn’t performance alone. It was whether that level of performance could be achieved without slowing the build down or changing a conventional build schedule for Regional Home Builders.
The Goal
The aim here was pretty simple. Build a house that actually performs in a tough climate whilst remaining on schedule and budget..
At the end of the day, success came down to whether the house could deliver real comfort and reliability, without costing time, bringing complexity, or stall momentum on site.
The Challenge
Once we moved past the idea stage, the unique site began to set the tone for a lot of early decisions.
The block’s steep slope became a defining feature of the design. Lifehouse Building Design leaned into this early, using the terrain to shape the layout and spatial flow of the house. The design layout responds directly to the site, with level changes and orientation doing real work for both function and form.
Orientation added another layer to consider. A large portion of the home faces west. In the Goldfields, that brings sustained afternoon heat, particularly during summer when temperatures regularly exceed 40°C. Without a considered wall system, managing internal comfort would have been difficult.
The Approach
The Cast & Block system was used on the western and southern elevations, where thermal load and temperature stability mattered most. Compared to traditional hempcrete, the system delivers around 40% higher thermal performance, creating a more effective buffer between the external climate and internal living spaces.
On the western side, the high R-rated blocks take the brunt of the afternoon heat before it reaches the interior. Along the southern elevation, the walls act as a thermal store, absorbing energy through the day and releasing it gradually. Together, they help stabilise internal temperatures without relying on mechanical systems to the same degree.
The system works quietly in the background, responding to orientation and climate while fitting neatly into a standard build process.
The Build
All 85 square metres of external hempcrete blockwork were completed in four days, using a small crew of one bricklayer and two labourers.
That speed came down to how the system is designed to be installed. The blocks arrive pre-cured, consistent, and ready to lay. Each course stacks cleanly, openings are straightforward to form, and the external side is ready to render without delay.
Height didn’t slow things down either. One of the western walls reaches 5.5 metres, a height that would have been slow and cumbersome using cast-in-situ hempcrete. With blocks, it was handled easily, with RespiraBlock only being 55kg/m2, we were able to move hempcrete blocks easily up high on the scaffolding.
Because the walls were already set, rendering could begin almost immediately. The build moved straight into the next stage without extended drying periods or downtime.
Efficiency
Based on standard cast-in-situ hempcrete benchmarks, the Cast & Block approach reduced on-site labour, eliminated extended curing periods, and allowed follow-on trades to start sooner.
Project snapshot:
External wall area: 85m²
External hempcrete block walls (85m²): completed in 4 days
Crew size: 1 bricklayer + 2 labourers
Hempcrete volume reduced by 1/3rd compared to a standard 300mm cast wall
Immediate transition to rendering and next-stage trades
The build moved forward without disruption, even while delivering significantly higher thermal performance.
Finishes and Other Details
Alt Text: Finished kitchen showing exposed hempcrete wall alongside timber cabinetry and stone island bench
Externally, the house is finished with a traditional lime plaster system from Rockcote. The finish has a natural, tactile quality that suits both the material and the regional setting. It’s breathable, durable, and works seamlessly with the Cast & Block wall system.
Inside, hempcrete features walls that add a different kind of weight. Over time, they give the rooms a sense of solidity, helping regulate humidity and soften day-to-day temperature changes without drawing attention to themselves.
This Castlemaine project demonstrates how the Cast & Block system performs when it’s used within a standard residential construction process.
The wall system performed within a conventional residential workflow, alongside a high-volume builder, on a demanding site, in a challenging climate. It delivered measurable thermal performance, speed on site, and built certainty without requiring special handling or compromise elsewhere.
It’s an approach suited to builders who value efficiency, designers focused on resolved outcomes, and clients looking for comfort without complexity.
Looking for more expert insights beyond this Castlemaine Hempcrete project? Take a look at our other helpful resources below:
