As a well-documented exercise in efficiency as a case study, Stand 47 explores an alternative approach to residential builds. Design-wise, it is both inspirational and aspirational.
If the journey is more important than the destination, then case study Stand 47 serves as a perfect example of this truism. This case study at Monaghan Farm near Lanseria in Gauteng has been documented throughout its four-step design and construction process on its website.
The aim of the joint venture between owner and developer Gavin Rooke, architects Thomashoff+partner and construction material producer Saint Gobain is to illustrate the process of building a house that “meets contemporary needs and yet remains flexible enough to adapt to future ones”.
Stand 47: Flexible accommodation
The project team has divided the process of this case study into four phases so the layman knows what needs to be considered when building an efficient house.
According to Rooke, the first phase is the most important step, one that is often skipped when people design a house – the design of the accommodation schedule.
Stand 47 is a three-bedroom house with a separate guestroom. Two of the bedrooms can be easily adapted as a study. The bathrooms are designed to close or open doors to three separate spaces or a joined shower, bath and toilet area.
It is relatively simple to change the layout. There is a single floor in the entire living area, and a single, self-supporting ceiling. This allows for moving entire walls, without any damage to the walls, floors or ceiling.
Paying attention to the walls
Several of the external walls used are ETICS walls, a Saint Gobain product consisting of eight layers, including a fire retardant, cavity insulation, expanded polystyrene, and a vapour membrane to manage moisture and air tightness.
“The R-value of these walls comes to 3.29m²K/W, compared to 0.35m²K/W for conventional buildings,” says Farayi Muhamba, technical expert at Saint Gobain.
The internal walls are made of load bearing steel framework and insulated drywall, additionally lined with Gyproc Duraline in the passage to make this high traffic area more durable. The walls in the bathrooms and kitchen areas are lined with 15mm of Gyproc Moisture Resistant board that makes the wall water resistant for 48 hours. If the boards cannot dry within 48 hours, water stains or mould could require remedial treatment.
The problem of mould growth is not limited to drywall systems though, as it can happen to a masonry surface too. Dry walling, however, is easier to replace.
The living area drywalls are lined with a layer of fire retardant and a layer of Gyproc ActivAir, a material that actively improves indoor air quality by taking VOCs and other pollutants out of the air.
Compared to traditional brick construction, building with light steel and the offsite, modular production system saved significantly in material wastage. It also saved up to 50% of construction time. In total it took only 183 days to build the entire house.
Sense of familiarity
Traditional building materials have also been used. The teak parquet flooring (from a sustainable source), rock walls and wooden window frames were used to give people a sense of familiarity.
There are limited options available for energy efficient window frames. According to the latest building regulations, aluminium window frames need to be insulated, which is expensive.
“We liked wood,” says Rooke, “but it weathers and needs a lot of maintenance so we started looking at alternative woods. Hard woods are very expensive but handle the Highveld climate much better.” They eventually found a local company, Rhino Modified Wood, which treats soft woods, e.g. local pine, to get the characteristics of hard wood.
Stand 47 challenges
Architects had to find solutions to address simple connections such as openings in walls, windowsills and roof overhangs, and careful detailing in the planning phase was crucial.
“It is a young industry and there are few companies that can work with these materials properly. There are only so many light steel suppliers,” says Rooke.
“There are only so many people who know how to apply the ETICS system. Especially when you want to combine with more traditional building materials.”
Evan Lockhart-Barker, general manager marketing at Saint Gobain, says: “The one big lesson on steel frame is that it requires a lot of clever thinking upfront.”
Another challenge was getting approval from the Tshwane Municipality, a process that took about three months. This was the first light-weight building that had gone through their system. Lockhart-Barker: “To get approval, we organised training of the building inspectors through SASFA and we had to demonstrate that the building methodology meets the requirements of current building regulations.”
This case study will be on show until halfway through August. It will be fully furnished, so people can experience the home. Thereafter it will be put on the market.
The full feature appears in the June-July 2014 issue.