After 6 years researching, planning, drawing and building for our sustainable house extension we still made mistakes! By sharing the journey we can help others meet their goals more easily.
The Main features are:
- Solar passive design to reduce environmental costs for lighting, cooling and heating.
- The downstairs floor slab (made of 90% recycled aggregate, ceramic and glass pieces, polished and sealed) is earth-coupled to minimise temperature fluctuation.
- Insulation for maintaining temperature and minimising noise.
- Fire resistance preserving the building for future generations.
- Durable construction and mostly hand built.
- Low toxicity LOSP frames, mesh not chemical termite protection, natural oils for painting, no plastic except in the waterproofing membranes, ample ventilation to provide fresh air. Avoidance of PVC as much as possible (alternative was HDPE).
- Low embodied energy the cement slab has 90% recycled aggregrate and a polish finish reducing need for floor covering.
- Recycled materials such as recycled timbers for rafters and external flooring, seconds for internal ceiling and flooring, recycled and repaired windows, recycled timber for archetraves and skirting. Recycled metal for balcony (see detailed photos below).
- Conserving existing features by blending with the old section of the house so that very little had to be re-clad or demonlished.
- Preservation for conservation with use of natural oils to preserve timber.
Lessons learnt:
- Check all suppliers well before you need them, even so, some suppliers may change the rules. For example our choice of floor oil was no longer available except by their pre-approved tradesperson. This made it unsuitable for our schedule.
- Be flexible or have a back up plan. Some suppliers might say they have the product and then there is a long wait when they find they don’t have the quantity or quality you need.
- Buy recycled items well before you need them including all timber (this means you need to have somewhere clean and dry to store the timbers). It can take as long as 3 years to get large timbers.
- Get Qualified. Our extension specified the grade of timber needed for joists and posts. If we had got our own qualifications for accessing timbers (able to check them for F ratings) we would have been free to source them from a variety of places. There is a standard (available from Standards Australia at your local library) for assessing timber, it is worth a read. Alternatively you could find someone qualified in assessing timber and pay them to visit a range of recycled timber yards.
- Know the product and procedure before consulting with the tradesman. Do your research.
- Draw the details so that the tradesman (especially plumbers and carpenters) know what you are wanting.
- Be prepared to listen but don’t be easily swayed. Don’t just settle for what the tradesman wants to do. Tradesmen, especially plumbers, are rarely faced with customers who question what materials they use. Often the tradesman is not aware of the toxins within the materials that they commonly use.
- Be prepared to pay more. Unfortunately using safer materials can cost more for
several reasons: the tradesman is not familiar with the product, the product takes more time to use (eg. hardwood has to be pre-drilled, recycled aggregate is less viscious and thristier, old windows are usually out of square and need adjustments) and the product may cost more at the factory door. This is true of most materials and the reason why most builders choose a product is because it costs less. To convince the builder to use something else and expect to pay the same is unreasonable.
- Be prepared to get dirty. Old timbers need to be cleaned (especially if you suspect they were treated for pests in previous place of use e.g. chemical termite protection).
- Get skilled. Old windows and doors need re-glazing or sanding and repainting etc. Making recycled wood and metal mesh fly screens, adding awnings, fixtures, weather sealants under eaves helps improve the durablity of the home. Few builders are concerned about durability today and this is understandable because so much is wasted in modern society. One third of the municipal waste is building waste. This suggests that few homes are unaltered, so durability is rarely considered. Even the life of a kitchen is generally only 10 years and then it is thrown out and re-built.