Clutha magic - Concrete Insulation in the mountains

Posted October 4, 2023

Location: 1 Jackson Rise Luggate Heights

Project Managers: A & I Riding

Draughting: Aoraki Design & Draughting Ltd

Builder: Christie Brothers Building Ltd

The Brief

This property is nestled between mountains that overlook the Clutha River. At the heart of this project was the end goal for the home’s occupants to absorb the beautiful 360-degree views from this stunning location. It was crucial then to design a home that brought the outdoors in without compromising comfort and warmth. 

The Challenges

The biggest hurdle put in front of us at the planning stage was being told that there was “way too much glass to expect any significant insulation results.” With full glass windows, 4-meters high all the way along the entire front of the home, we had to find a way to make this work. 

The Results

Our approach resulted in an open, light, spacious, and warm home, with a distinct feeling that the outdoors are in your living room.

To achieve the desired insulation targets, we focused on small incremental improvements throughout each stage of construction. We spent many hours researching all available products and paid special attention to the finer details. 

For windows and joinery, we engaged Michael Brenssell from E13 Performance Windows - Vistalite. His vast problem-solving skills along with Vistalite’s excellent systems, helped us to meet this aspect of the brief. 

For the foundation to meet the same challenge, MAXRaft® was the only system with a proven perimeter thermal break. After seeing tests and live examples of what ‘not to do’, there was no doubt that MAXRaft® was the only way to go. 

Installing MAXRaft® was one of the quickest parts of the construction process. It took roughly 3-4 days, and the subcontractor on-site was by far the easiest to deal with. They arrived at the agreed time which is rare for contractors. The staff were easy going and the technical details were at the ready for council and our draughtsperson. MAXRaft® made it a truly pleasant experience.

Life After Construction

The home has been occupied since December 2019 and the owners state that the results are continuing to impress them, especially as the cooler months set in. They’re ecstatic with the insulation results and how little it impacts their monthly power expenses. They didn’t use any additional heating during April or the beginning of May, due to thermal daytime gain, despite outside temperatures dropping to 3 to 4c. 

Because of how much effort was put into planning their insulation, the owners like to keep track of how much heat they lose over time. For instance, after using their heat pump for an hour they only saw a 0.8-degree drop in temperature over a 3-hour period internally, despite it being 6-degrees outside. The MAXRaft system created a huge ‘heat sink’ that holds overall gained heat.

When they have turned on their underfloor heating, they set the temperature to 23-degrees celsius (floor temperature). They set it for approximately 1-hour at 9:00 pm, then awake to 19-degrees celsius internally, while it was 5-degrees outside. Needless to say, they’re very impressed with their results and look forward to basking in the warmth and beauty of their property for years to come.


  • MAXRaft® 250, 120mm concrete with underfloor heating and full 50mm thermal break to the entire perimeter. 
  • Siga External Membrane & Siga Internal Membrane to all exterior 140mm frames with Knauf Earthwool Insulation R4.1 & R 6.3 to ceilings. 
  • Siga internal wrap was installed using only their double-sided tape – no holes created – thus creating a SIPS style Construction. 
  • Vistalite Aluminium Ltd (E13 Performance Windows), using Pacific Thermal Suite incorporating High-Performance Low E with argon gas, airtight system that added the most insulation possible with such a mass of windows. 
  • AirMax Ltd - Air to Water heat pump underfloor heating system.
  • A 200mm of tiles to the entire house to pick up the thermal gain.


Previous Article Next Article