The final straw

Gratuitous picture of Trevor

A few hours ago, I placed the final piece of straw in the final light-earth wall.  The structure of the building is done. 

Actually, it was a great way to finish off - I tried out a whole new technique for a different type of wall that we will probably use next time.  More on that later.

Last weekend, TJ put the roof on the bump-out.  That's him on the roof looking groovy with his new hammer drill (a Metabo, replacing the Makita that burned out twice - the Makita fought the shed and the shed won).

This weekend we mudded the last external wall, which was the triangular gable above the window-seat roof.

North wall core completed

The last bit of light earth on the exterior of the building was the gap between the frame and the roof above the new gable panel, to keep critters out of the roof cavity.  I had to get up on the window-seat roof and lie down to get my head and arms underneath the main roof's overhang.  Intensely uncomfortable. 

Gable - done and critter-proofed

You'll notice we buried the raw edge of the window-seat roof in the gable wall.  This is the sort of easy finishing detail you can do with mud but nothing else. It will never, ever leak.

Then we made an interior wall next to where the wood fire will go.

This final wall was an experiment to see if we could make a really solid thin wall, because I think the foot-thick walls on this building slowed us down a bit. If we do this again (TJ needs a woodwork shed) we'll do thinner walls.

The main challenge was to find a way to make the light earth stick firmly to a single stud, instead of having a double-stud "larsens truss" with a cavity in the middle to hold the wall.  After all these months of using bamboo to solve problems, the solution was obvious - TJ drilled holes in the frame and slotted in lengths of bamboo that spanned between solid wood, so when they are buried in a rigid wall they will be completely immoveable. I think in a stud wall for a new building, the bamboo would be horizontal, like a noggin, between vertical studs.

Single stud frame, cement sheeting and bamboo in place

The frame was backed with cement sheeting, to protect from the wood fire.  

Making and positioning the light earth took most of the day, but we completed 3.5m2  - more than double the area we could have built of foot-thick walls.   Don't get me wrong, I adore the thick walls and the curved lintels.  But thinner walls take less than half the time, which is not to be sneezed at - it might have knocked 6 months or more off this project.

Light earth, piggy-back formwork, wall-top technique

The photo above actually shows the last bit of straw we will use in the building.  We ran out of straw at that point and had to scrounge around for fibre to finish the wall.  But it's a good spot to look at the building method, and what we've learned.

Formwork made from scrounged MDF, but reinforced with pine boards.  The pine is offset so one board slots into the one below. In the gap above the top formwork (not usually as big as this, but meh) use a thin metal object like a float, or in this case a plasterer's hawk, and shove the mix in from the side.

And that's it.  The last wall in place.  When I walked outside I looked at the building and it struck me that I've lifted tonnes of mud and straw into place, bit by bit.  And I've grown some muscles, let me tell you.

New wall.  Now it's just fit-out, floor and render