Using permaculture ethics & design principles to transform an old energy guzzling bungalow into a showcase of sustainable design. It's about energy cycling, building community, self-reliance,creatively using & reusing materials... all without spending heaps of money.

Tuesday, June 30, 2009

The big deconstruction

Principle 12: Creatively use & respond to change

You may remember, from earlier posts, that I was looking at relocating the original building. After removing the lining from inside the building, we got a better idea of the condition of the structure. And it wasn't as good as I would have hoped.

While all of the framing timber is hardwood, which was good, there were signs of termite damage in parts of the frame. We could have still used it, replacing the damaged sections, but we decided that it would be easier to dismantle the building, and reuse the timber in other parts of the new structure. We will use termite-treated plantation pine for the framing instead.

Termite damage


The tools of deconstruction, and the results...


Battens and weatherboards.

Framing timber and tiles

An audit of the materials from the deconstruction (see more here) of both the house and the old carport deconstructed earlier:
  • 200 metres of floorboards (150mm x 20mm) @ $7.00p/m = $1400
  • 150 metres of battens (25mm x 50mm) @ 60c p/m = $90
  • 390 metres of weatherboards (170mm wide) @ $2 p/m = $780
  • 300 metres of hardwood (35mm x 90mm) @ $2 p/m = $600
  • 175 metres of hardwood (45mm x 90mm) @ $2.75 p/m = $480
  • 45 metres of hardwood (45mm x 75mm) @ $2 p/m = $90
  • About a dozen large sheets of corrugated iron @ $2 p/m = $72
  • 9 cement sheets (1200mm x 2700mm) $?
  • 750 concrete tiles $?
  • 6 sets of louvered windows $?
  • Lots of trim and smaller bits of timber $?
Total hours worked: 116
Materials valued at $3512 (not including tiles, cement sheet, windows or bits & pieces)
That's about $30 per hour return on labour.

Considering the cost that would have been incurred to demolish and dispose of the materials, deconstruction has proved here to be a cost-effective alternative to demolishing. Deconstructing also reduces transport costs, materials in landfill, and the need for new materials - lowering the overall carbon footprint and reducing waste.

Sunday, June 21, 2009

Slab it up

Principle 6: Produce no waste

Ordering the correct quantities of materials on a building site is a real challenge. How much does a cubic metre of sand look like? Experience tells. At A$60 per cubic metre for sand and A$213 for concrete you want to make sure you get your numbers right - or at least close.

All up I used 14 cubic metres of packing sand during this stage and 6.6 cubic metres of concrete. Structural concrete requires a mix of approximately 3 parts stone, 2 parts sand and 1 part cement. Both the sand and river stone were sourced within a couple of kilometres of the house site, not sure about the cement yet, while the supply depot is only 500m away. So transportation costs were kept to a minimum. The reinforcing was sourced from Sheparton, about 75km north.

I've spent about A$10,000 on getting the slab up, including excavations, materials and labour.

Quentin spreads the first 200mm layer of packing sand. The 'Bobcat' was used to load the sand and is in the process creating a base for a large watertank using excess soil from the excavations, which will give the water a small head which will allow for gravity feed.

A form was set up with recycled timber so that I could screed the sand to the correct level.

The sand was loaded and leveled in three layers. After each layer it was compressed with a 'whacker'. When the timber form was removed I could shape the sand using a trowel - hours in the sand pit as a kid put to good use.

The cavity between the brickwork was then filled with concrete and reinforcing bars set in place before it sets. Structural concrete sets quickly, so you can't muck around to much. Also best to order more concrete than you need, as being caught short can be problematic - as we found out.

Plastic sheeting covers the sand to act as a moisture barrier and slow the drying time of the concrete, giving it greater strength. Plastic chairs raise the reinforcing mesh to the correct height and wire is used to tie it into place.

The wire in the foreground was set up by the electrician to earth the reinforcing, so that the plumbing (which is earthed) and slab are both the same - avoiding potential electrical 'tingles' through a wet floor. Formwork was set up to hold the wet concrete in place for the pour. We made sure it was strong and level to avoid problems for the concretor - he was impressed!
We ordered 5.8 cubic metres of concrete, and there was six of us on hand for the pour. A vibrator was used to remove air bubbles and help move the concrete around. Scott, the concretor, ensures the slab is level using a laser level and a giant screed bar with level attached.

7mm river stones were spread over the wet slab, which will be revealed after it gets cut back and polished. Scott uses a bull float to get a nice smooth finish.

Scott and Quent have a cup of billy tea while they wait for the slab to dry enough to trowel over. Pouring a slab at this time of year (Winter Solstice) is a great way to ensure that your slab dries slowly, you just don't want heavy rains during the first few hours. Fortunately the rain was mild during the pour - a bit nerve-racking all the same.

It seems that our calculations were out with the concrete order by about one cubic metre (which is a lot - we played it a bit too safe). We set up some formwork for support columns at the entrance of the cellar for excess (right of pic), but had way more than we needed. So, we used the rest to fill in around the outside of the cellar (left). This will give the structure added strength, while avoiding waste.

Thursday, June 11, 2009

Brick by Brick

Principle 7: Design from patterns to details

I managed to access my brick supply again with the new neighbours. The 'low hanging fruit' had already been picked, so the collection was much slower going than earlier on (took about twice as long). I moved a massive pile of bricks in order to find unbroken ones to clean. In a deal that I made with the neighbours I put aside the best bricks for them (the solids) collecting only the 'wire cuts' for myself. Wire cut bricks are more brittle than 'solids', but are fine for the job I have in mind. I've collected and cleaned about 2800 bricks, hopefully that should be enough.

The last load of brick delivered on site, thanks to the help of James and Liam.

Now that the footings and cellar floor are in place we can start laying bricks. Thankfully Peter knows what he is doing, even though he's never trained as a brick layer - just learnt from others. He's passing on his knowledge to Quentin and I so that we can do some of the grunt work.

While the basic plan is in place, we are figuring out the details as we go.

Peter sets up the corner bricks, ensuring they are all level and square.

The work progresses, the southern side is left open so that we can access the area with wheelbarrows.

Stringlines are a key to keeping brickwork straight. The idea is to lay the mortar down and tap the bricks into place, to the height and line of the string without touching it. You can see how crooked the insulation line is, we will have to figure out how we can link that with the insulation that fits on the brickwork later.

Outside skin almost complete, now the inside begins. The metal bars sit between the brick skins, and will tie the concrete into place when it fills the gap.

Nearly done. You can get a pretty good idea of the size of the living / dining area now. The low winter sun streams across the entire floorspace - good passive solar design.

The sump got tested out the day after we poured the slab, seems to work well.

Peter set up a jig for the brickwork for the cellar, so that we get a nice even circle.

The sleeve that holds the horizontal bar in place is adjustable so that the height of each course can be set level all of the way around.

Peter sets up four piers within the walls for added strength.

Sunday, June 7, 2009

Excavations Part Two: The cool duct & cellar

Principle 8: Integrate rather than segregate

In the low energy future that we face we will need to be able to store food in cool places without using the huge quantities of energy that freezers and fridges currently consume. I was inspired by the cool cupboard design that David Holmgren and Su Dennet used at 'Mellidora'. The idea is that cool air is drawn from a cool space (in their case, under the house), up through a cupboard and out a metal flue pipe in the ceiling. Fruit, most vegetables, cheese, butter and eggs can be stored in the cool cupboard for reasonable lengths of time at temperatures of around 10-15 degrees centigrade. While it does not replace the job of a fridge, it does reduce the need for a large fridge, reducing electricity consumption considerably.

The cellar will be used to store preserved and bulk foods, where more room is needed. The idea of integrating the cellar and cool cupboard makes sense to me, drawing cool air from a cool space - but comes at a price. Warm air will be drawn into the cellar constantly. After much discussion I believe that this will not have a big effect on the effectiveness of the cellar, as the space is surrounded by cool thermal mass which will help to regulate the temperature.

The cellar will sit about 1350mm underground, the roof of the cellar will be 1m above ground level and a 5000 litre watertank will sit on top. This will give a small head for the water (allowing gravity feed) and provide thermal mass above the cellar. I am considering siting a header tank for the house on a stand above the cellar/water tank.

While the footings were being cleaned up I got Dave to work on the excavations for the cool duct. Peter worked out where the duct needed to come up in the future kitchen. We started there, with a depth of about 600mm and ran back down to where the cellar is to be located at a depth of 1500mm.

Dave used a 600mm wide bucket for the cellar excavation, which required a lot more fill to be removed. The ramp leading down will become a stairway.

Although it was the plan to keep all materials on site, there was far too much fill from the excavations than I could use on the small site. A local truck driver was contacted who arrived soon after. He took two loads of fill where it was needed around the corner at a cost of A$120. All up (Bobcat & excavator) the earthworks cost A$592.

After Dave left the site we realised that the trench for the cool duct needed to be 500mm, not 400mm. While the duct itself is 400mm wide, we need some extra space either side for screenings to sit, extending the life of the duct by allowing water to drain around it. This required some hard work with a pick and shovel.

A 50mm layer of 20mm screenings was laid down (Two cubic metres of screenings cost A$100 delivered).

Next, the ducting was fixed together with pop rivets - two 4m lengths and a corner piece. The duct was then lowered into place.

Screenings were then scattered around the edge of the ducting. Levers were used to ensure that the duct stayed centred.

About 50mm of screenings covers the duct before a strip of builders plastic is laid in place. This will divert any water to the sides of the trench.

The fill is replaced over the plastic, and the duct is fixed into place. The air inlet for the cool cupboard will be within the cellar at a depth of 1400mm at the lowest point.

A sump (black plastic bucket) is placed at the base of the duct to collect any small amount of water that may run into the cellar. Reinforcing mesh is placed on 'seats' to lift it off the ground, ready for the concrete pour.

The concrete pour happened straight after the pour for the footings. Our calculation of 4.6 cubic metres was a little short to complete the job for the cellar floor, so we ordered another .8 cubic metres (A$1130). A concrete vibrator (A$66 for half day hire) was used to remove excess air from the mix and help level it. It also helps to compact and make the slab stronger.

Peter screeds the slab after letting it dry for a couple of hours using a trowel. He uses a piece of cement sheet to kneel on to spread his weight.

Tuesday, June 2, 2009

Excavations Part One: Getting your footings right

Principle 8: Integrate rather than segregate

It's been a big week, with big machines, lots of people and heaps of money spent.

It's probably easier just running a bit of a photo essay here, with comments below each photo. I've divided this into two sections as there are really two projects going on at the same time. There's the raised slab footings and the cellar with cool cupboard duct. As both projects need the same machines I decided to do them in tandem. I also have had a lot of people working with me during the intensive phase to reduce the workload and potential problems.

Dave and his son return to dig the trenches for the footings, 300mm wide by a minimum 525mm deep. It's difficult for a big machine like this to work on such a small site; I think Dave did a pretty good job. You can see the telephone cable, and further up the water pipe broken through - I was expecting that.

The soil was very dry and crumbly, with many tree roots. So the trenches needed quite a bit of 'tidying up'

Quent helps Peter find the 140m AHD, 300mm above the highest recorded flood level

Peter directing Quent in the laying out of reinforcing steel

The trenches needed to be enlarged slightly (20mm), so that the insulation could slot into place, and still leave 300mm for the footing. Bits of timber brace it from the inside, which will be removed during the pour.

A clever suggestion from visiting mate Brian was to use his gardening mesh to help get a straight edge on the insulation. Thick wire was bent in half to form 'pins' which hold the mesh in place, while the ends of the mesh are bent on the inside and outside of the insulation to grip it.

After marking the level that we wanted the concrete to pour to (see 'V' bottom left) we set up metal bars on bricks which were used to tie the upper layer of reinforcing steel in place, 50mm below the concrete level. These were lifted out before the pour, and put back in place when the pour was complete.

After months of no rain, it rained, turning clay into sticky mud. Sand, which will be used as fill to raise the slab, is used here to create a safer working space.

We ordered 4.6 cubic metres of concrete for both jobs, requiring a rather large truck to negotiate the small site. Wheelbarrows were used to move the concrete into place.

A frantic hour or so with one guy on the truck, two guys on wheelbarrows, two guys on shovels and myself with a giant vibrator (which helps level and remove air from the concrete). It was important to backfill the outside of the insulation as the concrete level increased, to avoid blowing out the insulation.

The finished insulated footing, with steel rods inserted into the concrete, in preparation for the next stage. Plant tubes on rods to reduce the risk of injury.

Coming soon, Part Two: The cool duct and cellar.

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