Innovative home building

Building your own home is far more stressful than buying one. However, there are several construction products on the market that can make the process easier and more cost-effective. Here are four alternatives to conventional bricks and mortar.

Photographs courtesy of Garth Gainsler, Craig Paton-Ash, Mike Tremeer and Pieter Silberbauer

Any construction project is a significant investment in time, materials and resources. This is why more owner-builders are educating themselves about alternatives. At the same time, builders and property developers are also recognising that, by continuing to use the same materials and methods that have always been used, they are not addressing the problem of high building costs. The ideal alternative material offers design flexibility, environmental responsibility, energy efficiency, long-term structural integrity, durability and lower home-operation costs. It is along these criteria that we have isolated the following methods. Apart from timber-frame houses, maintenance costs and requirements for the other three methods are similar to those for conventionally built homes. Foundations are standard across all processes.

TIMBER-FRAME HOMES

Timber framing has been used in construction for more than 600 years and is widely used in Northern Europe and America. In South Africa, there are many examples of timber homes, some of which were built more than a century ago – an indication of the durability of this building method. Thanks to modern timber treatments such as anti-fungal and beetle treatments, timber homes can last indefinitely.

Left: Modern timber-frame homes have come a long way in their 600-year history and can last indefinitely due to special treatments applied to the timber.


Structural timber is treated against termite infestation and fungal attack. The timbers are then cut, shaped, and finished, before being sent to the building site where specially trained crews erect the house frame. Timber frames are then clad with insulated exterior sheathing panels, which can be installed very quickly. Fire-retardant materials and firewalls are also incorporated, making these structures very safe. Enclosing the timber framework from the elements as quickly as possible allows follow-on trades, such as plumbers and electricians, to work under cover sooner.

Advantages
Timber is a superior insulating material. External walls and flat ceilings are filled with bulk insulation, resulting in a home that is cool in summer and warm in winter. These homes can be clad with fibre-cement panels, which require less maintenance than conventional plaster. A timber-built construction can also substantially reduce noise levels – even better than double brick walls. The material cost of a timber-built home may generally be a little higher than that of the average home (refer to Comparative Savings below) but the long-term benefits of living in and maintaining one are an entirely different story.

Applications
Timber homes are perfect for sites that may present expensive-to-solve problems for conventional brick-built homes. This is because they are particularly adaptable to tricky sites with steep gradients.

Comparative savings
Good-quality timber-frame homes tend to be more expensive. However, in the long term, the benefits of insulation, energy efficiency and the unique aesthetic of a timber-frame home should be weighed carefully when comparing costs with an equivalent structure made of bricks and mortar. Quality timber-frame homes also have an excellent resale value. As opposed to a conventional house, a timber home can be erected in less time using less labour. Supervision and labour costs will therefore be lower than for a bricks-and-mortar structure. However, due to higher material costs (and location aside), a 150m2 , three-bedroom home, excluding finishes, could be constructed for around R600 000 as opposed to a similar bricks-and-mortar structure that would cost R525 000.


ECO-BEAM AND SANDBAG HOMES

Left: This beautiful home looks just like a conventionally built one, but it was constructed in less time using less money.

The Eco-Beam and sandbag system was developed in South Africa six years ago by engineer Mike Tremeer as a way of providing low-cost housing. Today, timber-frame and sandbag homes have found their way into many suburbs across South Africa, as this building process – and the specific design of the materials – is particularly cost-effective.

The building process, which can be undertaken easily without using highly skilled carpenters, is very simple and owner-builders can complete many of the stages that are involved themselves. The method consists of three elements: a framework of Eco-Beams (timber and metal beams that form the framework for the sandbag walls); specially formulated geo-fabric bags, filled with sand and stacked between the beams; and, finally, the cladding of the beams with wire mesh and either plaster, timber or plasterboard. The completed structure is waterproof (sand does not have the intrinsic capillary action found in cement), fireproof and soundproof, and has very good thermal properties. While standard walls may develop cracks in the plasterwork that can carry through the entire wall, this will not happen with this process, as cracks cannot run through sandbag walls.

Advantages
Eco-Beam and sandbag homes can be produced and built in a short period of time, as no actual brickwork needs to be done. Once the beams and bags have been transported to the site, the framework can be erected within a few days. Design features such as curved walls or unusually shaped windows that would represent an increased cost in a brick structure would not be the case here. Once the framework is in place, filling and stacking sandbags can be undertaken by semi/ unskilled labour or by the owners themselves, reducing labour costs. Much of the sand required to build the structure can be obtained from the site.

Applications
This form of construction is ideal in isolated areas, as the weight and design of the construction material makes it easy to transport. Sites with lots of sandy soil are ideal.

Will I be given a bond?
Yes you will. There are two independent organisations in South Africa that are concerned with technical approvals – the SABS and Agrément South Africa. While the former operates in a wide range of areas, the latter confines its activities to the building and construction industries. Agrément SA is the authority that governs and assesses the use of innovative or non-standard construction products. The National Home Builders Registration Council (NHBRC) also serves to protect housing consumers by monitoring quality standards in the home-building industry. In order for banks and building societies to grant a bond for any alternative building process, a valid Agrément certificate and NHBRC approval must first be obtained. Visit www.nhbrc.org or www.agrement.co.za for more information.

What about insurance?
Johan van Schalkwyk, Underwriting Manager at Santam, says that at this stage most buildings insured by Santam are built using conventional methods. 'We seldom receive requests to insure buildings constructed using alternative materials and processes. We do currently insure several structures built with wooden frames. These requests are subject to various enquiries before being insured, and the premium is worked out according to a tariff scale, rather than the standard rate. 'However, the South African Insurance Association (SAIA) is currently investigating the establishing of guidelines regarding the insurance of buildings constructed using alternative materials and methods.'

Comparative savings
Apart from the benefits of insulation, energy efficiency, eco-friendliness and the ability to use unskilled labour, an Eco-Beam frame building could represent a saving of more than 15% on the overall project costs if some, or all, of the building processes are undertaken by the owner. As opposed to a conventional home, an Eco-Beam and sandbag home can be erected in less time using less labour. The reduced contract duration, use of site resources (sand), supervision and labour costs could end up representing a total saving of 15-45%.

Location aside, a 150m2 , three-bedroom home with reasonable standard finishes could be completed for around R250 000, as opposed to the equivalent bricks-and-mortar structure that would cost around R525 000.

STEEL-FRAME HOUSING

Right: Lightweight steel-frame housing has evolved to be the dominant means of construction for domestic housing in many countries, including Australia, New Zealand, Canada and the United States.

Lightweight steel-framed housing was developed in the United States during the 1970s in response to similar issues as those currently affecting the South African building industry: productivity, quality control and availability of skilled trade labour. Even though lightweight steel framing is widely used in half a dozen countries, it is a relatively new process in South Africa. A completed home utilising an internal steel frame is virtually indistinguishable from homes erected using standard methods. The quality of construction can, in most cases, be superior to that of bricks-and-mortar structures.

Steel-frame housing involves modular construction in which sections of a complete home are built in the factory and then erected on site, often without the need for cranes. Houses are then clad with face brick, plastered brick (single- or double-brick layers), plasterboard, timber or corrugated steel.

Advantages
Steel-framed homes can be produced and built to precise specifications in a controlled environment using computer-assisted design and manufacturing technology. These homes can therefore be custom designed to include almost any variety of features or architectural preferences. Once the homes have been transported to the site, walls can be erected within hours. Unlike the problems that occur in bricks-and-mortar homes, walls will not only be perfectly straight and square, they will also be precisely positioned according to drawings. This will
make it easier and quicker to lay tiles accurately and complete internal carpentry work, thus representing major savings in labour.

Applications
Often building sites have inherent problems such as extreme gradients. Steel-frame structures offer greater structural integrity in these instances.

Comparative savings
Steel-frame building could represent a 10% saving on the overall project cost and a 14% saving on the builders' cost. Unlike a conventional home, a steel-frame home can be erected in 40% less time, using 40% less labour. This is largely due to concurrent trade activity: follow-on trades (plumbers, electricians,
carpenters) can work under cover sooner. You will save somewhere around 15% on building a single-storey home and as much as 25% on a double-storey home. The reduced contract duration, site resources, supervision and labour costs could end up representing a saving of around R85 000 on a R600 000 home.

INSULATED CONCRETE FORMS

Left: Even a trained eye would have trouble detecting whether this home was built with bricks and mortar or EPS blocks.

Insulated Concrete Forms (ICFs) is an innovative product that meets many of the challenges of alternative construction. The system calls for the use of expanded polystyrene (EPS) blocks and is relatively new to the Southern African construction industry. The use of expanded polystyrene as a building material is commonplace in the rest of the world. The foam EPS building blocks act as a permanent, thermally insulating framework that contains a steel reinforced concrete fill. The hollow foam forms interlock to form walls, which are then filled with concrete. Walls are plastered afterwards.

Advantages
This building method results in durable houses and the material is easier to handle than concrete blocks. The steel reinforcing offers extra stability. As with the previous two methods, the primary advantage of the ICF building system is speed and ease of construction. Walls can be built up to five times faster than normal brickwork. Depending on wall thickness, material costs vary between about 12% over and 20% under conventional building costs, depending on the scale of the construction. Any surplus material cost will repay itself in the first few years as a result of the high insulating capacity. Heating and cooling costs can be reduced by as much as 50% to 80%. In addition, ICFs also provide outstanding noise reduction.

Applications
This system should be considered as the building system of choice in areas with high rainfall or excessive damp. It is also a good choice for sites with logistical supply problems, sites in which wall weight is an issue or there are extremes in temperature, as well as sites with a lack of skilled artisans or unstable ground conditions.

Comparative savings
Besides the benefits of insulation, energy efficiency and the use of unskilled labour, the all-important time factor is worth considering: approximately 30m2 of wall work can be completed in one day – roughly four to five times faster than using traditional building materials.

Compared to a conventional house, an EPS home can be erected 40% faster. The reduced contract duration, site resources, supervision and labour costs could mean a total saving of 20%: in a case in which you planned to spend R600 000 to build using conventional materials and methods, you might only spend about R475 000 to build the same home using ICFs.

Further information
Below are a number of websites worth visiting. These online references will provide background information on performance, environmental aspects, design and technical details. It's always best to conduct thorough research.
• Agrément SA (www.agrement.co.za)
• Council for Scientifi c and Industrial Research (www.csir.co.za)
• South African Bureau of Standards (www.sabs.co.za)
• Southern African Institute of Steel Construction (www.saisc.co.za)
• The Australian National Association of Steel-Framed Housing (www.nash.mx.com.au)
• National Home Builders Registration Council (www.nhbrc.org)
• UK Timber Frame Association (www.timber-frame.org)

References
Information on the processes featured was provided by:
• Rustic Homes: timber-home specialists (www.rustichomes.co.za)
• Impacts: lightweight steel frame and truss systems (www.impacts.co.za)
• Styrox: EPS building system (www.styrox.co.za)
• Eco-Beam Technologies (ecofencing@telkomsa.net)