Graven Hill SIPs Panel Home
Outstanding fabric and structural performance on this ground-breaking self-build
Case Study6 min read
There are lots of things to consider when tackling your self-build – especially when your property is located in the flood zone for the River Thames!
Nick and Roxy Creak and their project team managed to overcome the challenges posed by the nearby waterway on their build, with Point 1 Building Systems designing and erecting the TEK Building System on stilts – safely clear of potential flood waters.
LOCATIONShepperton, UK
ArchitectSCd Architects
ProductsTEK Building System
The TEK Building System comprises Structural Insulated Panels (SIPs) with a high-performance rigid insulation core which is bonded between two layers of Oriented Strand Board type 3 (OSB/3).
The couple purchased the plot in Shepperton back in 2022. The existing single storey home that stood on the property was fairly dated and poorly insulated. They decided to demolish and start fresh, appointing SCd Architects to design the home and project managed the build themselves. The architects developed a stunning contemporary design with a double pitched roof, utilising metal cladding and timber soffit linings to invoke a marine aesthetic.
With its location just 8 metres from the river, the property needed to be raised on piled foundations to keep it above the potential flood heights. A steel frame with a beam and block floor was erected on the foundations to form a solid base. The couple considered a number of different options for the structural walls and roof of the house as homeowner Roxy explained:
“We knew we wanted something highly insulated that would be fast to go up and affordable. It also needed to be a proven system that we could get a mortgage on. The TEK Building System ticked all the boxes. Our build was BBA compliant 142 mm TEK SIPs for the walls and 172 mm panels for the pitched roofs. The panels also came with a huge range of calculated details with low psi-values – helping the design team to limit thermal bridges. The delivery partners, Point 1 Building Systems, also gave us confidence with their proven track record having worked on over 200 projects in the past decade.”
The TEK panels feature a proprietary jointing system which allows for excellent insulation continuity across the building envelope and, in combination with the OSB/3 facing, also allows the construction of highly airtight properties. To ensure good air quality within the property, a mechanical ventilation heat recovery system was also specified. This uses the warmth from outgoing stale air to heat, incoming fresh air, further limiting heating demand. This remaining demand could then be met with an air source heat pump connected to an underfloor heating system within the house.
Design and production
Point 1 Building Systems worked with Nick and Roxy to develop their initial concept designs into a final design plan for the TEK SIPs in CAD. Careful consideration was given to how to limit the use of structural steels within the property, both to manage costs and limit its embodied carbon impact. In addition, the designs called for exposed glulam ridge beams as a feature within the open plan space. By carefully planning the interactions of these elements at the design stage, the project team were able to limit unwanted surprises once they arrived on site.
Once the CAD plans were finalised, the panels were then scheduled for cutting at Point 1 Building Systems specialist facility using CNC routers. This ensured the finished panels precisely matched their design dimensions, with openings pre-cut for doors and windows. The offsite production process also allowed for clear scheduling, with deliveries to the site pre-planned to limit the need for site storage.
Installation
The erection of the panelised system was undertaken by the Point 1 Building Systems site team. Space restrictions around the site meant that careful planning was essential as Garry Dyke from Point 1 Building Systems explained:
“We carried out strategic site visits prior to the first site deliveries and liaised closely with the client and site team in advanced, carefully selecting the appropriate vehicle and plant. The timing and number of deliveries were also pre-planned with the site team and our contract manager spoke with neighbours to address any concerns ahead of the delivery.
There was a slight issue with the transfer slab steels, we identified this to the client on day one on site. The client and principal contractor arranged for the steel fabricator from the slab provider to alter the steel UB as per drawings. Within 48hrs the issue was solved. Our erectors simply fitted the soleplates onto stilts in this small, localised area to minimise the impact to our progress.”
Each panel was slotted over a sole plate, rigid urethane foam was then applied to the edge of the panel before the jointing system and adjoining panel were slotted into place and nailed. This approach ensures excellent thermal continuity and airtightness at the joints. Once the ground floor panels were in place, the structural steels and glulam ridge beam for the larger pitched roof could be installed and the roof SIPs could then be lifted and fitted. A breather membrane was then applied to the outer face of the panels ready for them to receive the external battens. From the first delivery, the erection of the structural shell took just 3 weeks to complete.
Homeowner Nick commented:
“It was an incredible experience, from the initial planning stages right through to final sign off we couldn’t have asked for more. Kris and the Point 1 Building Systems team were so helpful, gave us so much advice and finished it to such a high standard. We may be biased but it’s incredible that more houses are not built in this way – fast and efficient!”
With the shell in place, Nick and Roxy applied external battens to the outer face of the wall and roof panels and then fitted plywood outer boarding. The outer metal and timber cladding could then be fixed in place whilst windows and doors were installed. This allowed the internal spaces to be made weathertight, allowing internal fitout to begin at an earlier stage than would have been possible with a masonry construction.
The finished property provides a beautiful, modern addition to the river scene whilst also delivering excellent energy performance and low utilities bills. Its raised design has already proven useful after it sat safely above flood waters at the start of 2024.
