Steel-frame House Turns Heads Above Hout Bay Harbour
Nestled between indigenous vegetation, with a spectacular view of Chapman’s Peak and Hout Bay harbour, a new development, constructed by Silverline Group, altered the Houtbay skyline forever.
This 340m² triple-storey house took only four months to complete and has drawn attention from tourists and locals alike.
The owner has substituted conventional brick and mortar for his eco-friendly light steel frame (LSF) house – a growing trend in South Africa. Construction of the house produced very little waste and has an 80 percent smaller carbon footprint than conventional building practice. This project started at the end of February and was completed by the end of June 2014. The low mass of the structure and walling allowed the engineers to design a shallow concrete raft foundation with outer beams 450 mm deep and 250 mm wide and a 70 mm thick slab cast in recycled PVC Modulo Blocks. Compared to the heavy reinforcing and thick concrete for conventional building techniques this LSF house saved costs on materials and labour associated with the foundation and floor slab construction.
Once the foundations were completed, the ground floor walls were erected using LSF panels, fabricated from high strength galvanized steel sheet. The engineer specified the use of chemical anchors to bolt the structure to the concrete foundation. A LSF joist floor was erected on top of the walls and covered with fibre cement boards as the new floor.
The remainder of the walls were constructed with light steel frame wall panels fixed together with corrosion protected screws, ensuring a rust-free building in spite of its close proximity to the harbour. 9mm fibre cement board external cladding gave an overall external wall thickness of 133mm, with an R-value of 2.8 and a 1 hour fire rating. The R-value is a measure of the thermal insulation of the wall panels – the higher the R-value the more effective the insulation of the building.
Comparing the R-value of the light steel frame structure to a standard un-insulated double brick wall with R-value of 0.26, shows the superiority of the composite wall system that LSF offers. The LSF structure’s external walls consist of 9mm fibre cement board, fixed to the light steel frame through a thermal break layer and a Tyvek vapour permeable membrane, glasswool cavity batt insulation installed in the wall cavities followed by a 15mm fire resistant high impact gypsum board on the inside.
Internal walls consist of light steel frame panels clad with high impact 15mm fire stop gypsum boards (with a more than 30 minutes fire rating), and glasswool cavity batt insulation in the cavities, to enhance acoustic insulation.
The insulating layers reduce the building’s energy requirements for heating and cooling, with tests on the building’s total energy demands indicating that it has achieved a 17% to 20% improvement in energy efficiency, compared with those of conventional designs and due to the energy efficient design the buildings heat up faster in winter and cool down faster in summer.
With the light frame steel panels protruding from the roof, the house creates the feel of a warehouse inside – which was precisely the owner’s aim. The house is situated below the road and the architect designed a LSF access bridge connecting the house with the street above.
The house is complete with a four-car garage and two balconies overlooking the bay. All internal doors were cladded with metal plating in keeping with the industrial theme. Double LSF wall structures were used for load bearing walls which made it possible to eliminate heavy steel or concrete columns, resulting in a huge cost saving for the owner.
The net effect is a high end product that will last a lifetime.
Excerpt from Feel the Steel By the owner, Dieter Losskarn, freelance journalist
As a regular brick-and-mortar kind of guy, I was initially quite reluctant to build with anything else. But five months into the construction of my newest project and busy with the final finishing, Bay Harbour House in Harbour Heights, Hout Bay, I am a convert. Light steel frame houses are the future – especially in this country. Everybody talks about green and saving energy and this house does it so well. Even on really cold days, when a brick structure would be chilly as a morgue, the LSF house retains the daylight sun and is – even without any additional heat source – surprisingly warm inside. With a fire place burning, even my double-story, open-plan house will be pleasant and cosy inside.
It was also built in less than half the time of a normal brick structure. I loved the fact that the electrician and the plumber followed with their services through the wall cavities, instead of messily breaking and chasing through brick walls afterwards.
And you can bring all your own ideas into the project. The entire light steel frame for the construction is custom-made locally, according to your individual design and plan. Look at my new place. I wanted to create a warehouse-style residential home with lots of open spaces and a long industrial looking bridge into the first floor entrance. I could not have achieved this design with brick and mortar.
And even, if I sell this house in the future and the new owners would want to change things, it is easy to add an additional floor to a LSF house. Once you feel the steel, you never go back.
SOURCE: Steel Construction