Lining the ceiling

Its a few weeks now (time really does get away from you sometimes) since we finished lining the ceiling.  We decided to use ordinary pine lining boards (V-groove), as a reasonably eco-friendly material (Radiata Pine is plantation grown - and although there is some potential that the plantation was planted on what was previously old growth forest, most of the pine plantations I know are on what was previously degraded farmland, and it is renewable).

nailing the first board!

The lining boards were hand nailed to the bottom of the purlins, which allowed us enough space to put in some serious insulation (R5 batts), which  added to the wool blanket on the sisalation that was put in when the roof went on gives us (we think) a total of R7 insulation in the ceiling.  Not too bad, and will complement the high insulation qualities of the strawbale walls.

putting in the insulation batts as the boards go up.

It took us about one day to line each 'wedge' of the ceiling, working between our main beams that form the post and beam frame.  So sadly now much of that heavy timber is not visible, but a good insulated roof is more important that showing off big timber.  We got quicker in our methods, pre-cutting the angles on the boards (since each wedge is the exactly the same there were only two angles to cut, the centre angle and the outer facia angle).  The full ceiling is lined completely, including what will be eaves.

So about ten days in weekends, and its another big job done.  Its nice to start seeing 'finished' parts come together instead of digging away at trenches that will be filled in with concrete!

All done!

Now onto the most exciting part of building a strawbale house, the walls!

The great concrete pour

It was a very foggy and gloomy day (one of the few we have had all winter) that we finally poured the concrete slab for the house.  That was about a month ago now, time flies when you are having fun.

We had a crew of about five volunteers, and a paid concreter who was happy to work with us (harder to find than you would think!), and two guys who operated the concrete pump.  We had to hire a concrete pump (a line pump) as the slab site was just too far from the driveway to be able to shoot the concrete straight out of the truck, and while we contemplated it for a (very short) moment, we decided against wheelbarrowing 40 cubic meters of concrete!

the pump truck with concrete truck

pumping the concrete, first into the trenches, and then over the whole slab

it was a fairly relaxed affair!!

It ended up being a fairly relaxed day, nothing really went wrong, and the pace was calm.  The man who held the hose for the concrete pump certainly earnt his wages, he worked like a machine!  So now months of work is covered up, all those trenches and curved reinforcement....  at least we have photos to show for it all!

the boys 'hard' at work

screeding the concrete

our curvy slab, just finished.

its dry!

So now we have a lovely flat area, that will be our thermal mass in our house.  We designed the house to recieve winter sun (but not the summer sun) and its lovely to see how far into the house the sun reaches at its lowest point (to the halfway mark in the house).  This will be integral in our passive solar climate control, gently warming the house with winter sunlight. 

Now to save up for the next stage which is most likely going to be lining and insulating the ceiling. 

And your not going to see any of it!!!

Was the mantra that was repeated over and over by my labouring wife over several months of preparing the house site for the pouring of the slab. This is the last expensive thing we need to do before getting on with the relatively cheap mudbrick making. I really can't blame her it has been a bit of a slog but we can now see the end of this stage of the house build.

To ready the site for pouring the concrete slab it is simply a matter of digging the trenches, adding a layer of sand (road base?), boxing up, covering it in plastic and setting out the steel reinforcing. We have done these steps but of course we added an extra level of difficulty.

Firstly we put up the frame and roof before the slab, which is not normally the way it is done. The main reason we did it this way was to get the house build started quickly so that we would be able to extend our planning permit (ie. frame stage finished). It has had an advantage in that we don't have to worry so much about the weather when preparing for and when we eventually pour the concrete. But we have had to dig the trenches by hand (or pick, shovel and wheelbarrow), which added up to moving about 16m³ of dirt. This was done over a period of a month on the weekends. Because the outer edge is curved half the trenches ended up being curved. The total length of trench was about 160lm. The dirt we moved was dumped next to the house and will be used for the mudbricks and render later on.

The next step was covering the bits of land with about 8m³ of sand. This was done by wheelbarrow and shovel. We compressed the sand by hitting it with a bit of 4x2. The sand needs to be slightly wet to do this well, too dry and it won't hold it's shape, but too wet and it is too sticky.

The boxing up was also a bit different and I think a bit easier (and cheaper) than if we had a square slab. The entire outer edge of the slab is curved, so I decided to use 3ply because it is easy to bend instead of 6x2's that you would normally use. I used scraps of 4x2 and 3x2's upto about 500mm long to stake the 3ply. The bits of wood were staked to the ground with 250mm galvanized fencing nails (these will be re-used for fencing once the slab is done) and then the 3ply nailed to it. The slab is 150mm above the ground level so the 3ply was cut into 200mm strips. Because the 3ply is curved this adds strength to it and hopefully it will hold up on the day of the pour.

Laying the plastic we thought would be a bit of a nightmare seeing as how half the trenches are curved and at odd angles to each other and the added difficulty of working around posts. But it wasn't all that difficult and only took a day. We used about 400m² of plastic to cover an area of 200m², I guess it was in the up's and down's of the trench walls, the overlap of the plastic and a little extra in the trenches so when the concrete is poured it doesn't pull the edges in too much.

The last bit of the preparation really highlights one of the reasons most people don't make a round house. Trench mesh is straight and is really, really hard to curve. So we had about 80lm of straight trench which was easy to lay standard 3xL11TM in. The outer edge and inner trench which made up 80lm of curved trench needed to have 3xN12 bar, which is 12mm notched steel bar, which needed to be curved. This ended up being not too hard to do, but did add a lot of extra time over installing standard trench mesh. There also ended up being a lot of extra cutting of the slab mesh (SL82) because it has to follow the edge of the slab. We also had to navigate the 10 central posts and cut more than half the 18 6000mm x 2400mm sheets used to fit around the posts. But myself and the wife got the job done in about 4days with a bit of help from the kids.

So now we are ready bury the whole lot in about 40m³ of concrete, we just need to organise the concrete, concrete pump and helpers for the day.