Ayres Rocks

The image in the site header is the actual view we’ll have from the living areas of the house. Just thought you’d like to know where the picture came from 🙂

Those that know me will not be surprised I’ve already read through and taken notes on all the relevant information from the back issues of The Owner Builder magazine. One thing has been confirmed in my mind, and that is building with earth makes more sense than anything else.

The question is now which method is going to provide the benefits we want. 
The Methods
At the risk of insulting those who make earth building their lives, there are perhaps 4 methods of earth building, although there is considerable overlap between all of them. Again, without offending those that make this their passion, here is my oversimplified version of how things work.

Mudbrick–  60% of the world lives in mudbrick dwellings. Unfired, sun dried clay bricks is what they are. In Australia they are now typically stabilised with cement, lime or organic emulsions mixed into the clay slurry to improve weathering resistance and improve their strength for load bearing applications.

Mudbricks can be puddled, requiring lots of space, plenty of molds and incredible stamina to mix and pour the bricks into the molds. The brick mix for puddling is extremely wet, allowing for a slow cure that produces a very strong brick.

Pressed bricks use less water but some sort of  pressure to activate the clay and stabilising agents in the brick to produce a brick that could be used immediately, or left to dry just as the puddling bricks are.
Both bricks may have straw incorporated into them to improve insulating efficiency and also to lighten the bricks weight. A traditional mudbrick made in Australia would weigh around 20 kilograms.

Mudbrick is also known as adobe which in my world means bloated software. I believe the word is a derivation of Spanish/Arabic for brick.

Rammed Earth– Large form works are bolted into place and filled about 600mm at a time with a mostly sand mix stabilised with concrete or lime before being compacted inside the form work.

Poured Earth – smaller individual forms more like molds are used and a wet mix, again mostly sand with some clay and cement or lime to stabilise, is poured into the mold. The pour is allowed to set overnight, the mold removed and the next layer of bricks is mixed and poured.

Light Earth– A clay slurry is mixed with straw or wood fibres until all the straw is coated in the clay. This is then pressed into wall frames often made from woven timber strips, or as a newer and less time consuming alternative, over light steel mesh. The clay protects the straw, the straw/fibres acts as both insulation and filler again reducing the weight

Costing each method
I don’t enjoy paying more for something than I see value in. This often leads me down the DIY path, and thankfully for our bank balance and the wife’s sanity I am not one of those “Tool Time Tim Taylor” DIY tragics. Therefore I would consider trying anything, but only after research, thinking, research, planning, research, consulting, research and research. My figures here are accurate for the quantities involved, I even added 10% to cover incidentals. There are ALWAYS incidentals.

Mudbrick – I have no problem with digging a dirty big hole, taking the soil and mixing it with a stabiliser before using an hydraulic press to press a brick.
Cost approximations –
1 x 40kg bag of cement per 40 bricks. 4660 bricks = 116 bags of cement @ $12.50 = $1450
$150 to weld 2 molds, 1 working, 1 spare.
$420 for a 20 ton hydraulic press and a lightweight steel mesh safety shield. 
$9000 for a shed to keep the entire process out of the weather.
So a realistic cost for doing mudbricks, made by ourselves, is $3, 000 without the shed. (I won’t get a shed with any of the other options below either. Realistically any of these methods need somewhere to securely store machinery out of the weather but for comaprisons sake lets ignore the shed).

Interestingly to have the bricks made and delivered would cost around $17,200!

Rammed Earth – Specialist work requiring a LOT of experienced labour and a LOT of expensive machinery. We would also need to import a lot of sharp sand to cut back the heavier clay soil we have on the property. I have not honestly costed this option, I can do rough sums in my head and know that 2x bobcats at $100 an hour for a fortnight and 4-6 labourers on site is more than I am prepared to spend on hired hands.

Poured Earth – This one is tricky. We have plenty of soil that will need cutting back with some sharp sand to produce a better sand to clay mix more suitable for this. The volume of walls we will need to make is 58 cubic metres ( not allowing for any window or door openings), lets do these figure on needing to import the full raw material on to site.
Steel for brick molds – $400
Ply for brick molds – $450
52 cubic metres of sharp sand – $2240 (yes only 52, there will be roughly 6 cubic metres of cement)
Cement, 161 bags @ $12.50 = $2020
Realistic cost for this would be somewhere around $5600.

This would let us form 40 bricks 600x300x300mm per day, or around 24 metres of wall. Hell it wouldn’t take long nor be expensive to build a poured earth shed would it? Edit – No, it wouldn’t, $2000 for walling materials.

Light Earth – I’m still trying to figure out why you would bother with this method. It requires a framed wall, lots of steel mesh and amazing amount of patience as you literally take a handful of clay and straw and force it into the mesh. I don’t like the method nor do I particularly like the finished result. Straw can be expensive, the material needs to be screeded, it takes forever with manual or mechanical labour to turn clay into a smooth slurry and the biggest downside for me is I doubt you’d get a load bearing wall made from this method without extensive frame work behind it.

Speed of build
Time is money is time. I and the wife are self employed, if we are working on the house we are not earning any money. Quite simple really. The quicker we can get our building to lockup the better.

Mudbrick – I’ve seen believable accounts (read that as not on the site of the manufacturer of these presses and molds) from people who were able to make 15 per hour with 2 people mixing, forming and pressing the bricks. So we would also need 310 hours, and I’m guessing an 8 hour shift will be physically demanding enough so around 40 days of really motivated effort (ahem) to produce all the bricks. Lets be real and say 60 days or 2 months.

The longer the bricks are allowed to dry the more dimensionally stable they will become and the less shrinkage and possible cracking will occur in the walls when built, so lets allow 3 months drying time.

The bricks will weigh 20-25kg each making for a lot of really hard labour when it comes to laying the little blighters. Accounts from experienced mudbrickers suggest 100 a day for 2 people, including mixing the earth mortar and laying and pointing the bricks. Add in incidentals like moving scaffolding as you go, hot and/or rainy days, your body telling you to GFY and I’d expect 2-3 months as a realistic time frame.

That adds up to 8 months, 5 of which can be expected to be back breaking labour.

Poured Earth – I own a petrol powered mixer that can comfortably mix .099 cubic metres per load. (The real amount a mixer can mix is not the full bowl capacity, which is what you buy them by. That load works out to 3.5 cubic feet and the mixer is rated as 5.5 cubic feet.)

Some stats based on the verified capacity of that mixer:
It would take 15 loads to fill each set of molds.
It takes 15 minutes to thoroughly mix each load, maybe a minute to shovel each load into the molds.
The perimeter wall of our house is 72 metres, we would need 9 courses in height. I have worked this out to be 20 days @ 5 hours per day of work allowing for window and door openings.

I would need about a day to create the mold system after having all ply and steel parts precision cut so they only need to be bolted and screwed or welded together. This is where eager retired parent and parents-in-law come in handy. Especially when they also have their own welders and know how to weld. I’ll rabbit on about the mold system and the design specs and manufacturing in another post, if and when it becomes a reality.

So we would need 3 weeks to a month to get the poured earth walls built. Here we have the luxury of doubling the mold system for relatively small cost. Either way that will double the capacity or turn our mix and pour days from half to full, halving the days required.

Rammed Earth and Light Earth – I have read rammed earth is still time consuming and I can’t even begin to guess how much walling can be made by a team of labourers in a day. Light earth, well as above why would you want to? Certainly not for me but I’m sure it has its time and place.

It’s been quiet on the spending front which is not always a good thing.

Picked up a 1000L caged transport tank off ebay suitable for transporting water for our trees. The seller told me it held the dye they use to colour red wood chip mulch, which you would assume is non toxic. It does needs some cleaning, but the water I flushed through it and dumped on some weeds hasn’t managed to kill them after 7 days. More importantly it’s held the water level I left it with a week ago.

I’ve also ordered nearly 10 years worth of back issues from The Owner Builder Mag so we can sound our ideas off against the last 10 years of evolution in thinking and technique for owner building.

Cost for back issues and a 1 year subscription was $229.50 inclusive of freight.

Total spend to date is now at $214 182

Hellooooo, any tradespeople out there looking for any work?

You’d think not with the complete lack of response I have been getting from emails and leaving messages on phones.

I have found the draftsperson we will be using, Darren from Wise Drafting Pty Ltd. Darren realises the benefit to email communication and to date I think we’ve given each other scope on exactly what we expect from our client/professional collaboration. Yet we’ve never met face to face or had so much as a phone call.

For those tradies out there who have websites and email and think it is a pain in the butt, or too hard to switch on your damn computer let me explain to you why you should change your attitude.

Convenience
In my case I work with a lot of international clients, so my work hours do not always match yours. I don’t appreciate a call at 8am if I’ve just gone to bed after finishing tweaks to some work in real time with a client in Europe. I sometimes think of things or take a break from work and do some research at 3am, would you appreciate a phone call then?

Records
I juggle a lot of things at once. Many people do. Email gives you and me a written record of conversations and what we have agreed to. I do not accept phone calls from my clients instead insisting on email so I have written records of all correspondence to refer to when I need. Those clients that resist this initially are always convinced email is better by the time we finish the project.

Having these records has seen me prevail in cases where a client insists I have made errors. Simply forwarding their own email and pointing out the instructions “they never gave” settles complaints immediately.

Now, if you are an earthmover, surveyor, geotechnic engineer, sparkie, plumber or concreter and are willing to do some work out at our block in Tungkillo, there are contact details on this site to get that ball rolling. Darren thinks I will have a set of plans you can quote off by the end of June or early July.

I’m always open to barter for services too, the internet is my working life and I have more than a decade of experience in websites and marketing and work largely as a consultant to other website owners on design and improving ROI from their web activities.

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.

After the 100mm plus of rain 2 weeks ago, this week the block is looking lush and green. To be honest, in the 5 months we have been looking at this block of land this is the first time it hasn’t been dusty and barren. We’d imagined just how nice it would look once there was some green on the ground, and I have to say it is way beyond what we expected.

This is the view from the current driveway. The fence line to the left is the northern boundary. Directly in front of the car is the current woodlot, which we did walk through and we estimate to have closer to 300 trees now we have seen the full extent of it.

We used the dayglo paint and stakes to mark out where we want the house and the septic to be located.

If you can pick out the crossed stakes over towards the left of this pic, they mark the septic while the stake to the right  is the southern most point of the house. One thing that is really becoming apparent is the area is so vast it’s impossible to take photos that give any real feeling of the size.

After marking out the house we went back and drove from the proposed new gates down the driveway and into the garage that will be part of the house and it was nice and easy and flowed comfortably which was good. I now have the OK from the wife to order the steel posts and RHS steel to weld up the gates which we’ll need to install before trucks can enter and leave the block easily.

As of now there are maybe 150 trees in the existing woodlot and maybe 40 significant red gums across the rest of the property. My new best friends at Austrahort Seed Merchants supplied me with a few thousand river red gum seeds, ironbark and maculata (spotted gums) as well as tens of thousands of acacia victorae.

So far I have 300 river redgums seedlings sprouted and moved into tube stock. These will become the base of our woodlot next spring to be planted once the frosts have stopped. This should be enough for our firewood needs managed as described in the post about woodlot management.

Currently we have the first of 2500 acacias potted into seedling trays and in the mini greenhouse.  We will be using these as commercial seed trees, acacia seeds being a native food and keenly sought after for the nutritional and health value. Once the acacias sprout and can be moved on into tube stock the ironbarks and maculata will be next.

The spotted gums are sought after lumber for fine furniture and beautiful decking and will be planted with a 20 year harvest in mind, like a small super fund. The ironbarks are so incredibly strong they will be staggered 4 deep as a windbreaks around the property line and around the perimeter of paddocks for the same reason. They are also a commercially in demand lumber.

We are looking to plant out 300 red gums, 2500 acacias, 10 000 spotted gums and 10 000 ironbarks plus fruit and nut trees in our orchard. Potentially we have the capacity for 20 000 acacias in addition to the above, how many we end up with will be left to farm gate/market returns for the seed.

One thing is for sure – our block will be a green and thriving oasis amongst the thousands of hectares of cleared grazing land around us.

After making yesterdays post and showing it to a friend, I got the question back “How can you have a wood lot, cut it down and expect it to regenerate itself?”

Here is my simple explanation of how it works. I am not an arborist so some of the terminology may not be pure of explanation, but it will give you the gist.

In forestry management there are 2 techniques used to cut timber and allow the root stock to regenerate. “coppicing” and “pollarding”. Both of these techniques are used by savvy gardeners so they can enjoy the foliage of what would become a massive tree in a manageable and renewable way.

Both of these techniques result in regrowth from the stump of a felled tree. Depending on the species in the woodlot, these processes may be carried out many times with a typical loss of 10% of stumps each time the lot is cut. Cutting can be timed to suit the use of the timber, for firewood 15cm diameter trunks may be ideal, for lumber the trunks may be allowed to grow larger to ensure good straight wood can be processed from the trunks.

We are hoping 5 years between cuts will give us good sized firewood and allow us to maintain the woodlot sustainably.

It is important to make any cuts to the trunks at an angle so water does not pool on the cut stump which can encourage rot in the timber.

Pollarding
This technique involves felling the tree in a traditional manner, leaving half a metre or more of the stump. What then happens is dormant buds in the bark of the stump shoot new growth and these eventually become the new trunks of the regenerated tree.

Careful selection of the shooting growth is then done and the strongest 3-4 are allowed to continue growing while the weaker shoots are smashed off the trunk with a blunt instrument. These are not cut, since the clean cut would encourage more shoots to start from this point.

The disadvantage to pollarding is the resultant growth can be extremely unstable and easily broken away from the trunk. The advantage is in areas with a lot of frosts the buds are higher from the ground and may be more likely to survive.

Coppicing
With coppicing the tree is cut as close as practical to the ground, preferably with no more then 15 cm of the trunk remaining. Again, dormant buds in the bark will shoot and new trunks for the tree will be formed.

Elimination of all but 3-4 of the new shoots happens in an identical way for the same reasoning.

The disadvantage to coppicing is the new shoots are more likely to suffer in frosts and also more likely to be eaten by wildlife. The major advantage is the remaining trunks are stronger than with pollarding and a tree subject to coppicing generally survives more generations of regrowth.

Major advantage of both techniques
Both techniques allow for quick regrowth off of the cut stump. While some root die back will occur, the large root system of the original tree allows for quick water and nutrient uptake into the new trunks. Growth is quick and vigorous.

Major disadvantage of both techniques
The downside to both comes from the ability to regrow new trunks with amazing vigour. Soil nutrient is very quickly depleted around the root zone and heavy applications of manure and mulch to replenish these is required.

So for those who were also curious about just how a woodlot can be regenerated I hope my lay-mans explanation has answered your questions.

I’ll make these seperate from other posts so if you want to see where we have spent cash you can do so by selecting the “Project Costs” category from the right.

So far, our expenditure had been:
Pegs, jute (twine) and paint for marking out – $76.70
Settlement and block purchase – $213 875.77

Total to date is a mere $213 952.50

We have big plans for our patch, tempered only by the fact we want to establish a lifestyle with the cash proceeds from the sale of our house and any money we earn in the meantime. Put simply, we will go at the project until we have reached our reserve cash limit, then its back to work to earn enough to complete the project.

We already know we don’t have all the cash on hand to finish which is a nice reality to be honest. “Can’t spend what we don’t have” budgeting at its purest.

Our immediate plans are to re vegetate certain areas, mainly as windbreaks as the wind up here can be severe. Once this is done we will establish a large woodlot, which will be used to grow timber for firewood and perhaps structural uses such as fence posts later.

We are about to put before council plans for a shed of 15 x 6 metres, 9 x 6 of this enclosed for a workshop with a 6×6 carport for sheltering the cars in wild weather. Off the shed we will have 50 000 litres of rainwater storage. This storage will provide our legally mandated 22 000 litres water storage for bushfire fighting and that leaves 28 000 litres of storage for the green house and vegetable patch and for us to use during the build. These tanks need to have hardware compatible for CFS (Country Fire Service) trucks to take water from if needed to fight fires.

This shed also means we need a proper driveway placed close to it. Again, there is mandated widths and access roads for fire fighting equipment and vehicles that I need to carefully research before we go ahead with that. The shed is only 20 metres from the road boundary so it won’t be a huge imposition to make a path for trucks to the shed tanks.

Down the hill there will be a green house with attached chook shed and fenced veggie patch. All this will be designed with permaculture in mind so each area will have multiple uses other than growing vegetables or housing chickens.

Running off this area will be the house, with orchard linked to the chook shed and vegetable patch to allow the chooks access into the orchard.

The house is going to be large, 28 x 9 metres of actual living space with a further 2.4 metre wide verandah right around the perimeter. If I claim the size of the house like your typical real estate agent does, the house will be around 41 squares in size, or 4110 square feet or 453 square metres.

Here’s a rough mud map of what we want to do in the paddock closest to the road. This is all proposed, currently the block is used for grazing and is a blank canvas. One thing you will notice is lots of water tanks, we want to have 150 000 litres of storage.

The angled boundary is actually an easement containing a buried water pipe for a property a further kilometre away. They were smart enough to place this just inside the paddock fence, making it easy to find.

There is currently a woodlot just past this easement, however it is not large and it sits in the lowest point where a dam would be perfect so as we cut this lot it will be with no view to regenerating the trees. The woodlot we establish as in the mud map above will be cut as a regenerating woodlot.

The fall from the road boundary to this easement is approximately 40 metres, with a plateau where the shed is and also where the house is proposed to be located. The shed will need 5 minutes on a bobcat to level where it will go.  We’ll need to cut approximately half the house base into the plateau up to 50 cm deep and fill the other half a similar depth.