Monday October 19 / Tuesday October 20
We started construction of 60k House at the beginning of what turned out to be the coldest winter in southern Tasmania for nearly 50 years. May was much wetter than normal and the ground was saturated. This was the main reason why we decided to have a break before we started framing up the building – to allow the weather to warm up and for the site to dry out.
There is only a thin layer of topsoil across the site – underneath is various types of clay, each stickier than the previous layer. Sometimes a short walk to the building will see you grow three inches from the mud on the bottom of your boots!
Once the ground had dried out it was time to get the excavator back onsite to complete the remainder of the earthworks. This included installing a fair dinkum drain on the top side of the building. We had dug a couple of temporary drains to divert the surface water away from the building during the early stages and now knew what the finished ground level would be.
Most rural areas of Australia rely on catching rainwater from the roof for their water supply – drinking, bathing and washing. Australians invented both the shower timer and the dual flush toilet to conserve water. Growing up as kids in the bush we learned to not leave the tap running while brushing our teeth.
All about that base
Tanks come in a range of sizes, shapes and materials. The corrugated iron water tank is quintessentially Aussie. If the tank sits on the ground it needs a level base to spread the load. Although the tank itself isn’t very heavy the water inside is – 1 litre = 1 kilogram. We used a 100mm deep layer of 7mm blue metal for the tank base, contained within a timber frame.
It’s easy to calculate how much water you can expect to catch in a year – the area of your roof (in square metres) multiplied by the annual rainfall (in millimetres) will give you the volume of rainwater in litres. 60k House has a roof area of 112 sq/m; Flowerpot has an annual rainfall of approximately 700mm – I can expect to catch around 78,400L each year.
How much water you use is dependent on you and the fittings. I used the conservative estimate of 120L/day per person to determine the size of the tank. I ordered an 11,197L Aquaplate steel tank (in galvanized finish) that would hold enough water for one person for three months – it never goes that long without raining in Tassie.
Just as we finished spreading the blue metal level across the tank base the water tank arrived. This was maneuvered into position before the fittings were added (outlet, inlet and overflow).
Costs: ag drain (pipe, blue metal) – $830; tank base – $273; water tank – $2,210
Disclaimer: Any advice contained within this blog is of a general nature only and cannot be relied upon. Details provided are in good faith and relate specifically to this project. Any author will not be held responsible for advice or information presented.