So what are we building? Part 1
Well, originally
If you had asked me this question before we bought the block I was sure of the answer. Ranch design, 3 bedrooms and 2 bathrooms in the main house with 2 guest suites and their own bathrooms under the main roof but not accessible from the house. Overall building would have been a massive 40 metres long, 9 metres deep with 2.4 metre verandah all round.
It would have been a steel portal frame (shed) engineered to comply with BCA codes for Class 1 structures (houses). We would have a mish mash of colorbond panels, blueboard with murals, stone facings and all sorts of other ideas to detract from the overall look of a shed.
The idea was we spend little on the structure, which lets face it is there to keep the good stuff out of the weather, but lavishly fit out the inside with quality fittings and fixtures and skimp on nothing.
But then
We found this block, with all its undulating hills that plan was not workable. We spent some time re thinking our plans before we bought the block to see what we could do that would allow best view of the block from the main living areas of the house.
This switched our design to a 3 stage build.
Stage 1 was the “sleeping” block with 3 bedrooms, 2 baths, an office and a living are that would serve as the kitchen as we built stage 2.
Stage 2 was the “living” block, with large open combination family, dining and kitchen and a generous laundry and store room being the other 2 physical rooms in that building.
Stage 3 was to be the guest suites, complete with their own living areas and bathrooms.
This design was well suited because we could stagger the buildings up and down slopes and link them with decking and well sheltered breezeways. This idea was kyboshed after an informal discussion with the council planners as it was not in fitting with the rural aspect of the surrounding areas.
So then
Well, we had to rethink things yet again. The ranch style design was still the favoured of the 2 we had, so we took some careful measurements on the block and worked out we could fit a 27×9 metre building into a plateau on the block and stay within council prescribed developments by not having to excavate or fill past their stated limits.
While the 40 metre design just would not work, by dropping off the guest suites and removing the under main roof workshop and garaging, we has the best bits of the original ranch design in a size that would be able to be built on the flat area we had indentified.
But now
I’ve always had an interest in being “green” which means I knew the idea of the shed was the devil because the energy consumed in mining the ore right through to the delivery of the finished product is enormous. This is called “embodied energy”. With that in mind we set out to see what we could build our house from that was more sympathetic to our green views.
Well, we have 58 hectares of Adelaide Hills land. If you know Adelaide you know the soils here are largely reactive clay. Our land is not as heavy in clay, and the soil would in fact be ideal for making mud bricks. Now we’re talking about technology used to build in the time before Jesus. The Great Wall of China is built from mudbricks, and it’s estimated 60% of the worlds population live in mudbrick dwellings.
Typically mudbricks are made in 2 ways – by mixing the materials to make a very wet mix, or “puddling” and by using a dryer mix compressed to form the brick. Puddling produces a stronger brick, but requires a lot more water and physical mixing as well as a larger area to allow the bricks to set in the molds. In both manufacturing processes the bricks are air dried rather than kiln fired as traditional clay bricks are.
By manufacturing myself a simple press made from a hydraulic ram and using a 10-20mm plate steel mold, we can make our own bricks on site by mixing dampened clay soil with some medium such as straw and using a very small amount of lime or cement to stabilise the brick. Compressing the mix under high pressure will activate the bonding properties of the clay and lime (or cement) and form a solid brick. The brick can then be released from the mold and allowed to air dry.
Most of the energy in manufacturing a brick in this fashion is good old fashioned hard labour, making the embodied energy of either method extremely low.
So now
I need to find a draftsperson sympathetic to this old school approach to building and have a design drawn up that will use our mudbricks as load bearing walls. This also means I will need to produce several batches of bricks in different mix ratios and have them certified as being load bearing, which can then be passed on to an engineer who can then give the council the paperwork and computations they need to see to verify the structural integrity of our house.
Why load bearing? Then we don’t need to bother with building any sort of frame and will be able to bolt the roof trusses straight to a top plate built into the walls. Doing this cuts down on the amount of material we need to source and have brought on site, making our house greener by the minute.
The only immediate downfalls to making mudbricks on site are time needed, space needed for storage and the sheer mass of the bricks. At around 90 tons thats a lot to store, and will also mean a huge variation from normal for the slab design.
But then again
I’m not committing to the idea of building with mudbricks. It will take 3 months just to get bricks made, dried and certified then at least 6 months to make and dry the bricks we’d need for the house providing we pass certification.
The largest problem with building green is the time and money required to get things engineered and approved. It is still an infant industry and the technologies are just not widely enough used to make them cheap options. What someone on Tasmania has done can’t be translated to a site in Perth for example without the approval, testing and engineering process being done again to suit the Perth site.