Ayres Rocks

Being 38C today gives me an opportunity to sit in aircon comfort and crunch a few numbers.

Blocks poured to date – 467.42
Bags of cement used – 213.5
Blocks per bag – 2.19
Cement cost per block – $3.84
Sand cost per block – $1.55
Blocks per square metre – 5.55
Wall cost per square metre – $29.91

Cubic metres poured – 23.69
Guesstimated cubic metres wasted mix – 3
We are getting better at managing the wasted mix but it is not completely avoidable.

Amazingly, after weeks of frustration due to weather and everything else life could throw in the way we are finally getting on with pouring the walls to the house. These blocks are 50% larger than the blocks poured for the power room and are presenting logistical issues on mixing and handling that much at one time. We are mixing 40 litres of soil, 50 litres of sand, 10 litres of cement and up to 20 litres of water to get each mix to a consistent standard. That translates to 70-80 litres of mud ready to pour once it’s been churning in the mixer for 15-20 minutes each load.

Pic 1 below shows the set of 3 blocks that separate the windows between bedrooms. Pic 2 is the detail of how the threaded rods are being positioned. Those rods are holding the large redgum blocks as seen in the lower block in pic 3. Pic 4 is the second layer completed on one of these window bays. At the base of all layers is a 20mm thick strip of redgum, sealed with linseed oil and anti mould that will be used to fix skirtings to once we are at the final fit out stage.

All of the fixings are M10 nuts and bolts and the 1/2″ square to hex drive converter (that is the simple name the hardware people have for these gadgets) means any drill can be used to quickly spin bolts in and out. I set the torque on the drills to about half of the maximum so there is plenty of play with getting stubborn bolts back out if needed. Pic 1 below show the gadget in use. Pic 2 is the lovely scenery I’m looking over while working, and the view from all living areas of the house. Pic 3 was an attempt at perspective.

Setting up for this base layer is cumbersome and very time consuming, but since the moulds will literally fall into place for the subsequent layers we are happy to take this stage slow and get it right. Setting up for this stage consists of lots of measuring, remeasuring, coffee, remeasure then just a quick measure and check once more to make sure it is right.

Quite frankly the long range weather outlook is rather bleak with plenty of rain affected days to come over the next few months. In view of this I’ve just ordered enough steel and formply to double the current mould system shutters.

Since the dividers can be removed without actually exposing any of the drying earth mix these will not need duplicating, but the dividers they sit within will also need duplicating. This way when the sun shines I will be able to “make hay” (40 or so metres of wall) over 2 days and still allow the 2 day drying time that seems to have worked with the power room when we were experimenting with method.

Perfect weather would see us have the walls finished in under 9 weeks using the time per block we achieved with the power room during our testing. Since we can’t control the weather we’ll just do all we can to use fine conditions to our advantage instead.

Power Room
Foundations have been dug for the power room and after encountering a lot of large rock I’ve had to rethink how the slab will be laid.

Originally we were going to dig, reinforce and pour the slab and beams in one shot, now we’ll customise each of the beam reinforcing mesh configurations to avoid as much of the rock as we can. We will use some booker/tie rods protruding from the beam and then pour the ring beam by itself.

This will also lift the base of where the slab was to be by about 150mm to accommodate the required beam thickness. Once the beam has had a week or so to set we can then fill and compact that 150mm with crusher dust, lay a sheet of forticon and pour a slightly thicker slab with heavier reinforcement on top.

Mould System
All the testing and configurational tweaking is done and the system is ready for action. All we need is a power room slab to get started on. I have made a few small changes to pieces of the system just to make assembly of it quicker and easier for one person to handle.

Soil Tests
Tests are completed and we will be adding 10% sharp sand to the soil and cement mix. The soil is actually OK without it with minimal shrinkage in the test sample but since soil can vary in composition and we want a uniform finish, we will use the sand as a buffer that will avoid drastic changes to the mix as the build goes on.

Tour Down Under
A great event for the state and also a great pain in the ass for anyone that lives near or needs to travel along the stage routes. TDU passes through Tungkillo this year and rolling road stoppages with an enormous crowds travelling to and then lining the roads is going to make travelling to the build site to hard to bother with for 2 days this week.

Site Loo
With instructions from the plumber the site loo is now in place. It has shall we say million dollar views and a “light and airy” feel to it. Unfortunately the camera was forgotten in the scramble to get to the block after I finished work Saturday, so photos of the progress will be uploaded after next weekend.

Boom Lift
The crane has taken shape and sits in the yard tacked together enough to play with the functionality of  it. I need to rethink a couple of things the major one being expanding/reducing the physical footprint and the minor ones include things like wheel placement and other manoeuvrability issues. It will not slew so being able to turn it with load in place is going to be important.

Life keeps getting in the way with family and the many birthdays around this time of year so things just seem to keep getting delayed. However, this weekend we shall be setting up the foundations and footings for the power room and pouring the slab early into next week.

All the mould system has been completed and is just going through the final “what if?” scenarios to make sure it truly is as flexible as I have designed it to be. I am so far happy with it, the proof will of course come in that first row of blocks of the power room itself.

To help with all the lifting of earthen concrete, the formworks and later the roof trusses, I have designed and am about to start building a boom lift controlled with a hand winch for horizontal movement and a remote controlled 12volt winch for rise and fall. It’s substantial enough for me to confidently predict it will lift the 100-150kg loads I expect it to encounter at heights to 6 metres. It will be easy enough to move with a jockey wheel to lift one end off the ground and a pair of 200kg rated bearing wheels at the other. The base will be welded flat welded box section with the rest of it bolted together so it can be flat packed for moving.

What ever flavour of religion (or not) you follow here’s hoping you’ve survived the mayhem and chaos of family, booze and excess food of the silly season.

My list of things to do before we start building is rapidly disappearing with odds and ends being completed and tested. I have 2-3 days of tinkering left before the list is complete and then we are on the build, just in time for summer proper to get here.

That will present a few challenges with New Years day here predicted to hit 39C with a wild drop into the low 20’s for the following Sunday. I’m not quite sure just how the earth walls will cure when there is such a huge fluctuation in ambient temperature. My gut tells me the more consistent the temperature the stronger the cure but I can’t find any reliable information sources to back that up. With that in mind the start may be delayed until into the new year when things stabilise temperature wise.

I’ll get some pictures of the finished shutters and the odds and ends up some stage this week on flickr so you can see what I’ve been up to.

I’ve just about chewed through 5 kg of welding rods in finishing off various bits and pieces of the mould system and ancillary inventions. My dad is coming over next week to give me a hand with trimming up all the formply so I can bolt together the shutters and various custom corners to finish the mould system. Once these are done the very final bit of welding needs to be done to the dividers and that is adding the top locator bolts.

I must say I am very happy with how the system has come together, when you check out the very first idea I had for the dividers

then compare that to the end result

you can see how much lighter they will be for a start with about a third of the steel needed. The lighter design did need a lot more thought put into it to ensure some accuracy across all the pieces. The final design will have a thin sheet of oiled MDF placed either side and that will allow easy removal of the divider from the set blocks with the MDF then being gently peeled off the set face of the block, re oiled and then set again for the next run of blocks.

I put together a 2 stage soil sifter as well. We can sift down to 20mm aggregate by adding a removable mesh cage. This will be good for the walls and should give a nice smooth and uniform finish. The larger mesh filters down to 50mm, and that larger aggregate will be used in the retaining walls around the place.

The stuffing around bit is in the soil tests we are conducting to work out the additives we need for the soil. So far I’ve done a couple of “shake tests” to seperate the soil particles into solids, sand, silt and clay and it looks like the soil is around 15% clay. I’ll run 2 earthen concrete shrinkage tests over the next week with soil as is and the soil cut back with 10% sharp sand by volume, both with 10% white cement as stabiliser.

If I put this in writing then I have something to stick to……

I put my business into a halt a few months back after realising I cannot devote the proper time to it to make the money to build the house while building the house. I have since found work driving trucks on an afternoon shift run which guarantees money with fixed hours. The hours are favourable enough for me to drop in home, pick up an esky with some supplies and head out to the block to sleep. I should be able to get 5-6 hours work in before having to head back home, grab some lunch, clean up and head back to work. Weekends I’ll simply camp on the block and head back home Monday morning for work.

I have made some modifications to the old truck, ripping out the rear seats and forming a flat platform large enough for an airbed for one with considerable tool storage underneath. The tandem is also getting some mods done to be able to chain and lock larger tools (generator, mixer, formwork and so on) I don’t want to be bringing back and forth each day and this will be left on the property, chained to a very large concrete block.

The Walls
We are planning to start the actual house in the days following Christmas. Our plan is to have it weather tight by August. We have 920 blocks to make with formwork already made to pour 16 blocks in the 5-6 hours per day. I’ll allow myself 3 months to get the walls done.

The Windows
All the windows are being made by us from recycled hardwood from the species required for our bushfire zone. Iron bark and redgum are some of the acceptable timbers we can choose from. These won’t take long to make since I can set up a couple of router tables I bought in preparation for this and simply spend a day machining and cutting wood. The frames will be installed unglazed and I will pay a glazier to fix the glass once they are in place.

Having done this volume of work with recycled wood when building the kitchen in the last house we owned I know it will take around 7 days to machine, cut and assemble the 14 windows, 2 sets of french doors and the front door and side light.

The windows and doors will be deliberately rustic in nature with lots of wooden dowels being used and left visible for some interest. They should look right at home next to the mud walls.

The Roof
Footersville and Lysaght will be contacted for a firm delivery date once I have a clear picture of a finishing date for the walls. The walls will need 4 weeks to cure properly before we can load them so there will be a heck of a mess of bracing in and around the site until the trusses and wall frames are in place to take the bracing loads.

Our biggest challenge with the roof will be weather, the calm periods around our site are rare and short lived and it could take days or months to fit the roofing iron dependent entirely on the wind.

So we have around 4 months of work to get done over 8 months. It should be achievable and the date is firm as one of us is celebrating a milestone birthday and we’d like to have it in our own home.

I was on the block over the weekend getting some labouring work done for the plumber. The slab looks great and we’ve been so lucky with the weather with mainly overcast days and a fair amount of rain spread across the day. Here’s hoping those curing conditions give us the strongest slab possible.

The plumber has been hard at it connecting the drains to the underfloor plumbing. The amount of fall by the time he’s wrapped the pipe around the slab and started heading it out to the septic tank is around 1.8 metres. That’s some major site excavations. With some dumb luck he has not found any huge lumps of rock, instead being able to bash his way through with a jackhammer. That works out cheaper for us than a rock breaking excavator for sure but will still blow out his bill somewhat.

Never mind though, we’d had visions of being $10 000 poorer after the site cut revealed those huge lumps of rock so the $3000 or so bill resulting from that is a more pleasant result.

In the mail today was the official council stamped copies of our development application along with a little letter culminating in the words “APPROVED”.

Yay! Now the easy bit is over with it’s time to get on with the preliminary planning and coordination of the excavations, concreting and under slab plumbing.