Self-build new home

SPACIOUS YET THERMALLY EFFICIENT HOME

Client: Bill Reid

Architect: Denholm Partnership Architects

Location: Kinclaven

Project: Five-bedroom new build

The Project

The client wanted to create a spacious and thermally efficient new-build home that would require little to no heating. As he intended to self-build the two-storey, five-bedroom house (350-metre square footprint), ease of build was an important factor in deciding the construction materials.

Having found that the traditional build approach to mitigate against rising energy bills is to make houses smaller, the client needed an alternative build method. He searched the market and discovered that Durisol ICF could meet both the thermal performance and self-build requirements.

The Durisol system is straightforward to use, so the client could complete the build himself as desired. In doing so, the client saved money by not needing to employ expensive tradespeople and realised his dream of building his own home.

Design

The plans included a heat recovery system to keep heating costs to a minimum and reduce the home’s environmental impact. The insulation afforded by the concrete core of the Durisol system ensured the heat recovery system was a viable inclusion.

A tricky design feature in the new property is a 30-square metre floating balcony. This stunning addition was achieved by cantilevering the balcony over a four-metre Durisol lintel. The D250 block was used for the lintel instead of the D365 as this unit has a greater capacity for concrete. In addition, three steel beams were anchored into the concrete of the outside wall above the front door. These beams cantilever over the lintel and protrude four metres out to form the upper landing, support the balcony and anchor the stairs.

The exterior design features three different finishes – 100mm thick natural stone (Denfind Stone), cement cladding (Cedral) and render (K Rend). The Durisol woodcrete units have a rough surface, providing an excellent key for the render and allowing the cladding and stone to bond directly to it. Given the weight of the natural stone, the stone cladding was built off a foundation as well as being bonded to the woodcrete.

Challenges

The build is near Perth on the East coast of Scotland, a zone 3 location in terms of weather exposure. With a large proportion of the project taking place over the winter months, the site was subject to the worst Scottish weather, including high winds, an abundance of rain and snow, and frost. Unlike traditional bricklaying, which is affected by frost, Durisol construction can continue in all weathers. So even on the sub-zero temperature days, the concrete pour could continue as the concrete was going into an insulated block. This factor was an essential element in keeping the build on track.

The client opted to use the 365mm-deep Durisol unit for the envelope of the build. This unit has a 120mm thick concrete core with 165mm of PIR insulation and is sturdy enough to withstand extreme wind even during construction. Lighter than a concrete block yet heavy enough to stay in place, the build was unaffected by the 70mph winds experienced on site.

Outcome

The finished result is an outstanding build that achieved the client’s aspirations for a spacious and comfortable yet efficient self-build new home.

The client was able to create the space required without compromising on energy efficiency. It is also a sturdy home that will withstand whatever the Scottish weather throws at it.

Despite the size of the property (700-square metres) and the Scottish weather, the house is drawing very little energy from the National Grid. Although this is due in part to the solar panels which have been installed, the house has extremely low energy demands. For example, at 11am on a late February morning with snow on the ground outside, the house was only using 361 watts of electricity.