Building Materials
General | Flooring | Porous paving | Bricks | Cement | Plaster | Glass | Steel, other metals | Earth/mud | Wood | Plastics | Bamboo/grasses | Straw Bale | Green Roofs | Building Materials Further Reading
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In the General Further Reading section, we talk about Built Green, a US organisation. One of the great resources they have produced is a series of free PDF's on what materials to use around the house: http://www.energy.wsu.edu/code/code_support.cfm .
The main thing about building materials is that they take energy to make and transport, and some are made from non-renewable resources (like those fancy granite kitchen counters…). Chapter 4 of The Natural House Book in our General Further Reading section goes into detail on the many materials you can use – from concrete to straw bales.
In South Africa the reality is that most houses are built of brick or wood. Brick is the most commonly used material - very few build with alternate products such as straw bale and steel frame. Although these alternatives offer very good techniques, they are as yet not well understood in South Africa from the general builders perspective. Steel frames have to be imported or custom made, and it is difficult getting a bond, insurance or council approval for such houses.
Try to source wooden flooring from a certified plantation that grows as sustain-ably as possible, such as rosegum from Zimbabwean certified plantations. Wooden floors are not good at retaining winter heat (see Passive Heat Control).
Some carpet suppliers advertise that they recycle carpets. Check with your supplier.
Stone and concrete is best for retaining winter heat (see Passive Heat Control) See below on cement. Stone is not a natural resource and stone quarries are not very environmentally friendly.
The more surface you cover, the more you tamper with the natural water flow and cycling. If you have to put paving down, consider porous paving which has gaps for grass to grow through, and which allows water to run off as naturally as possible. Contact your paving supplier for options.
http://www.terraforce.com/terraforce_products_terracrete.htm is one SA supplier
Try to go for locally produced, and clay if possible. Mud walls and bricks are actually very viable – but your architect and/builder will have to advice, based upon the local mud onsite where you are building.
Due to the large amount of energy required to manufacture cement (mainly electricity usage, but also mining and transportation), it has an extremely high carbon footprint and it's manufacture contributes to a significant percentage global warming. Again, try to purchase locally produced to reduce the transportation footprint. Cement is however well established as a product - it goes back about 2000 years – the Roman Coliseum is built from it. And although cement factories can spew out pollution just like any other – the end product is not harmful. It's also a great insulator and heat sink.
Concrete is made of cement (mainly)
Every year 1.9 billion tons of cement are made. The
manufacturing process creates major CO2 (as it’s energy intensive –
it’s made by burning fossil fuel to heat limestone and clay powder
to 1500C).
Cement is then mixed with water and gravel. This creates a
chemical reaction that forms calcium silicate hydrates – these bond
gravel to make concrete...
Cement production produces 7-8% of all CO2 WW.
Note that water runoff from concrete mixing has a high alkalinity, and
can be harmful to plants that aren't used to the pH.
Again, source a local supplier where possible. It is a great heat insulator.
In South Africa there is very little choice when it comes to glass. It is mainly supplied by PG Glass. They have some fantastic products for insulation (see Insulation) – we have no knowledge to comment on production cleanliness, apart from that it does require lots of electricity (there not many other replacement products for it though).
You wont easily avoid using metals unless you build a timer frame – and then you still need screws unless you're really dedicated. Steel production is very bad for the environment. Use as little as possible, where possible.
Great product – if used correctly (some SA architects and builders know how to make mud walls and bricks – we're talking extremely strong products here), however the problem is supply – it has to be done onsite, which means you need the material on your plot. The most common modern use is something called rammed earth, where mud is mixed with a bit of Portland cement (a particular mix of cement) – see The Good House Book, pg 26
No hardwoods, no exotics. Both are not grown sustainably. Use renewable sources. Timber must be treated in SA for wood bugs – this does result in harmful fumes. So consider exposed beams and poles carefully. The Natural House Book, pg 260, has a list of which woods to use.
Use local woods to keep the footprint down. Red gum (Salinga) is a good option
Use Forest Stewardship Council (FSC) wood –the global accreditation organisation for green forest certification. Forests are audited once a year. Wood marked “100%” is from well managed forests. Wood marked from controlled sources has less stringent standards. http://www.fsc.org/en/ .
An alternative window and doorframe supplier is Formwood who have a compated wood product http://www.formwood.co.za/Windowsdoors.aspx or http://www.nulu.co.za)
An alternative to wood is recycled plastic! Have a look at http://www.polytimber.co.za
Universal Timbers (Tel: 021 507 2628) are environmentally sensitive wood suppliers
This is a term that covers many types of products, mostly made from oil and coal, some from plants extracts, but all very different (think polystyrene vs. Gore-Tex!). Generally today it refers to synthetic materials made from coal and oil. The production of plastics has a very high and thus negative environmental footprint. So things like PVC window frames are a bad choice from that perspective – although they insulate better than aluminium (which also has a high footprint). So if you can't use wooden window frames, you're stuck between a rock and a hard place. Also try to get plumbing pipes that aren't made from PVC…
Uncommon in SA as a primary building product, however a good one. Bamboo is extremely strong – and renewable – it's just a type of grass. It yields 50 times as much fibre as acre as cotton according to Business 2.0 Oct 2006. Consider the massive footprint of buying imported bamboo from China though… Bamboo projects there apparently donate money to conserving the Panda, although we do not have a list of suppliers who are linked to these projects. Also, we have no knowledge of what Bamboo cultivation is doing to the environment in China.
Read more about the issues here:
As mentioned in the intro for this section, an unconventional yet good product. For now we suggest you search the Internet for “Straw bale South Africa” to keep up to speed.
Green Roofs organisation
http://www.greenroofs.org/
Green roofs and walls company
http://www.g-sky.com/Default.aspx
Building Materials Further Reading
The Good House Book (chapter 2) has some great information on materials (and building techniques), including the amount of energy required to make them and how efficiently they insulate (it's no point building from materials with a low environmental footprint if you end up using energy to heat or cool your house as they insulate badly or need replacing all the time). There are many things that can be reused around building - glass bottles for windows and old tyres in walls (extreme) are some examples the book goes into.