Chapter 11
ALTERNATIVE BUILDING METHODS
Introduction
While the term ‘alternative’ is often used for any building method other than bricks and mortar, most manufacturers of building systems that don’t use bricks prefer the term advanced building methods. However, the term alternative can also be used for any element of building that is different from the norm.
The reason for building alternatively would be to save money, save energy or save time in addition to ensuring a more comfortable living space. In their overview about their case study Stand 47 at Monaghan Farm, which was built using steelframe, Saint Gobain says ‘Less effort is required when a house has built-in capacity to change – as well as fewer materials, construction, maintenance and living costs. Questioning popular building methods involves looking at design and construction processes slightly differently to find innovative contemporary materials that achieve our goals for a better home’.
Materials
Steel frame
Steel frame is a light-weight building method and can be erected fairly quickly once a foundation is laid. The steel frames are clad with insulated fibre-cement board, once the cavities have been filled with cavity batting. Plumbing and electrical conduits are installed inside the wall cavities. The Stand 47 case study has yielded numerous statistics in how efficiently the building works – for more information on this, go to www.stand47.co.za.
Straw bale
Straw bales are stacked, much like bricks, on a platform or foundation with a moisture break or waterproofing, and then plastered to assist in waterproofing. The stacks are bound together with string or with wire-mesh. This is an ancient building material that is gaining in popularity as it’s made from a highly sustainable product (straw) and is easy to construct. The thickness of the straw bales also ensures excellent insulation, making it an energy efficient option.
Sand bag
Specially formulated bags of sand inside geo-textile bags are stacked between frames, either made of timer or steel. Wire mesh is then used to clad the walls; after which they are clad again with plaster board or timber. The Eco-Beam Sandbag Building System was developed as a solution to low-cost housing. There are three main elements to the sandbag building process. First a framework of timber and metal beams is erected, then geo-fabric sandbags are filled with sand and stacked between the beams. Beams are clad with wire mesh and either plaster, timber or plasterboard. Once complete, the home is waterproof, fire resistant and sound proof.
Timber frame
Much like steel frame, but with the cladding also in wood – this is an eco-friendly option, but not necessarily cheaper than conventional brick and mortar. Wood is a natural insulator and this helps reduce electricity costs. A suspended floor must be constructed first, after which the timber frame is built. Then the roof trusses are installed, followed by the roof covering and waterproofing. It’s important to ensure that timber used is from a sustainable forest.
Interlocking blocks
These can be manufactured using a concrete mix poured into plastic moulds and left to dry, or on-site using the mix pressed through a lock-making machine. Blocks are usually dry-stacked and need little or no mortar, using semi or unskilled labour. Depending on the interlocking block system used, site waste, energy and water usage are reduced. Homes can be built in far less time than brick and mortar structures.
Dry Wall
For interiors, dry-walling is becoming increasingly popular. Drywall can be used to construct walls or install ceilings in homes. Drywall has a foam gypsum core that is sandwiched between paper liners. Drywall is easy to work with and even people with average DIY skills shouldn’t have any problems with it – however accurate measuring is essential. Using drywall for interior alterations is far less messy than conventional bricks and mortar, as well as faster.
Methods
Kit homes
There are some kit homes on the market – meaning that you buy all the elements already designed and manufactured. These can be timber or insulated foam panels. Insulated foam panels can be used for floors, roofs and exterior and interior walls. These aren’t DIY options, however, and an engineer must be employed to design the foundations and a professional team used for the erection. One such example is a Structural Insulated Panels (SIPS) kit home. This is erected on a foundation designed and certified by a structural engineer.
After the foundations are complete, the kit will be developed and a professional team will erect your home. The kit includes SIPS wall panels, a complete roof structure, ceiling, insulation, pre-glazed aluminium windows, doors and first fix electrical conduits that are cast into the panels. Panels are heavily insulated and this eliminates the need for additional insulation. Additional electrical fitting and wiring must be completed by an electrician and plumbing completed by a registered plumber.
Systems
Instead of complete homes, there are some systems that provide the walls only for a home – interlocking panels that are erected on a foundation are becoming a viable option, with conventional building methods used for the rest of the construction (roof and finishes).
Design
Alternative design doesn’t mean a home designed like a Salvador Dali painting – it speaks to saving energy, time and money. Alternative design can make use of shared walls, for example in the low-cost housing market, instead of creating small standalone homes, making use of shared walls by backing homes onto each other, the costs could be reduced and home sizes increased.
Something that is clearly illustrated in calculating costs is that the design can have a massive effect on the cost of a home – using design to reduce costs while still ensuring a beautiful end-product (as opposed to a square) is an essential part of addressing sustainability. Today, designing with energy efficiency in mind is essential, and also legislated. Architectural professionals have to be aware of and take into account the energy efficiency of a building – this helps to ensure that buildings are designed more sustainably.
Labour
Different building methods require different labour types – from unskilled to professional or specialist. Many of the manufacturers of different building materials or systems offer training to assist in proper use or installation of their products. However, with future technology, we could be looking at 3D printing walls or using robots to build specific housing types.
References
Alexander G D . 2016: Buildaid Training.