"Previously on Buffy the Vampire Slayer ..."

This is the bit of the show where I present a series of flash-backs from past episodes you haven't seen.

The Mud Shed started with finding a spot behind the house that was flat, damaged and weedy, so we could justify plonking a building on it.  But it's very close to areas with very good native wildflower coverage, so we have to be very careful while we build - basically, we walk on set paths and do all the heavy work from inside the building.

We had a bloke with a digging machine come in and dig the foundations, and we poured concrete strip footings, with the guidance of another professional.  This is the minimum amount of concrete we could get away with using and still get a council permit.

We bought a steel 6x4m steel garage kit and set it up on the footings.  This was a difficult choice, because of the embodied energy of steel manufacture.  I might talk about that in a later blog - the compromises we made to get a building permit.

Then we scrounged hardwood four-be-twos from rubbish skips in Melbourne, bolted them together and slotted them onto bits of starter-rod we had embedded in the concrete.  The trusses are shaped like a ladder, 25cm wide, with a space between the uprights. I'll get back to the trusses in another post, because the width and the space between them are an important light earth engineering element - and if I was doing it again, I'd probably use a different design.

Then came the ceiling and the roof.  I'm scared of heights so I stayed out of that one.  TJ and his mate Rudolf fixed roof trusses to the frame, fixed the 5cm thick Solomit Strawboard ceiling panels to the trusses, put a layer of insulating foil over the ceiling then put the roof metal and roof capping on.

This photo also shows the shape of the footings.  There's a solar bump-out window seat on the north wall (facing the camera).  The pile of dirt in the foreground came from digging out the footings, and that's what we're using to build the walls - complete on-site recycling.

The photo also shows the drainage challenges we face.  There's no guttering on the roof yet, the land on the south and east (left and back of the photo) slopes towards the building, there are no eaves on the west (the right of the photo) because we have applied for a permit to add a verandah.  Add all that together and there's a bit of a tendency for the building site to become an indoor swimming pool after heavy rain. I'm not going to build the east wall (the one on the left) until this is sorted out.

But I couldn't wait to start playing with the mud, so I started anyhow.

First I put in a moisture barrier, which is 10cm of loose gravel held in by rocks on one side and pavers on the other - that photo is taken from above, looking inside the wall.

The rocks were left near the house by a previous owner - probably pulled out of the ground when the house was built.  The pavers were pulled up during landscaping works at TJ's mum's place.  I was pleased about getting this method passed by the building inspector, because it breathes much better than a plastic or tar moisture barrier.  Gravel prevents moisture wicking from the ground through the concrete footings into the walls and rotting them. The rocks won't wick moisture - or not much.  The pavers will, but not as much as brick because they are pretty thin, and anyway they're on the inside wall.  I wanted to use rock on both sides, but the rocks are really, really, really heavy and the pavers were so much easier (the walls are my job - I've managed to get by without asking TJ to lift any rocks for me).  This rock / gravel arrangement will also drain water out of the walls if there is a disaster.  I've left weep-holes on the outside for this.

The metal bar you can see embedded in the footing helps stop the wall moving sideways - "lateral stability" says the building permit.  You can also see the 5cm of visible concrete footing on the inside and outside of the wall. That's the only termite barrier in the building. The building permit guy wasn't thrilled with the idea, but he passed it.  The idea is that termites would have to build a mud tunnel over the concrete to get into the walls or ceiling, and we'd see it, so we could take action.  The building inspector's worry is that a future owner may not keep up regular inspections, but he was comforted by the metal frame.

Then on two incredibly exciting days (not a joke) we made the first wall. 

I'll talk about how we make the staw and mud mix in another post.

We started on the smallest wall - the one below the windows on the west side.  You can see how it works with the rocks - I really like that look.

That was the wall that got damaged later. You can see why.  It's the wall that will later have a verandah, so it presently has no eaves and no gutter. A week later, 50mm of rain fell.  The water from half the roof ran down the foil directly onto the top of the unrendered wall.  It wasn't very damaged, though.  The wall simply absorbed most of the moisture and let it evaporate out later - mud is brilliant at doing that. Some water dripped through the wall into the gravel and rock footings, which did their job - the water simply seeped out the bottom - I could see it happening the next day.  I'll just cut the top 30cm of light earth wall off and replace it.

Then the family teenaged holiday workforce arrived and did the heavy work on the south wall. 

This photo shows how light the straw-clay mix is, and how easy it is to place between the formwork. I taught the 12 year old in about five minutes, and she taught everyone else.

This wall was about three days' work, but we're only talking about 2-4 hours per work session - it is quite tiring and hot work but very fast.

We got adventurous on the third day and embedded an old aluminium-framed window in the mud - we bought the window for 50c from the Daylesford Tip Shop.  On the inside of it, we placed an old wooden sieve wrapped in plastic to help shape the mud into a circular window frame - you can see the sieve in the photo. We also put some bamboo in the wall around and on top of the circle to help keep the mud structure in place while it was wet - that was one of the teenagers' ideas.  If all goes to plan, once I remove the sieve and clean away the stray bits of straw with scissors, we will have a circular window framed in mud, ready to render.  It won't be able to open or close, but it will be very air-tight.

That photo also shows the next bit of rock / paver / gravel footing completed - I'm bloody glad to say I've done half the rock work now.  I'm going to take a break from that and see a physio and do some yoga.  The biggest rocks are about as heavy as I can lift, and I have to lift them each several times, trying this way and that, until they fit together neaty, then lift them again to mortar them in place.

So that's the story so far.

We won't be building this weekend.  TJ has to stay in town and it's going to bucket down with rain.

If the rain clears I might go up by train and bike on saturday evening and spend a few hours fidgeting with the circular window.