concrete and stone insulated and reinforced wall

This is the wall that we are currently building along the south side of the house (southern hemisphere, north wall opens to sun). The above shot is where its at right now. We are a third of the way complete along its length. I wanted to have a wall that would give the coldest part of the house (south side) a large thermal mass. It had to be an insulated wall (which this is) and it had to be built by hand by my wife and I.

This is where we started. The first corner block. We did various walls around the property adjoining gardens and terraces as a trial. I finally was drawn to the idea of completely forming the wall in sections that were manageable. 2400 x 600 x 650mm thick was the chosen size. The sheet of form ply fitted well cut into two, and the height ensured that there was not too much pressure on the formwork as it was loaded up.

I constructed two forms, a corner mould and a straight mould out of RHS steel. I then fixed positions that threaded rod could be fed through conduit and tightened to keep the forms together. I will do some close ups of the forms next time i strip a block.

In the centre i used a 30mm styrofoam insulation which is fixed in position by silicon at sides and bottom and held vertical by a couple of welded bars that are removed after pour is complete.

down low on the wall are steel tubes 150mm diametre that will operate as cool air ventilation inlets into the house, allowing great cross ventilation, keeping the house cool in summer.

we found a neighbouring property that wanted to get rid of local granite they had all over their land. we got all this lighter coloured rock for free. we added a bunch of hard basalt from a quarry not far from here and mix the sizes and textures and colours as we go. We do all the concrete mixing by hand (9 mixes per block) and it takes us about 3 hours to pour each block start to finish. it takes a day to go off, an hour to strip and an hour to clean the block and the formwork. Two hours to set up for the next pour and off we go again.

i put two keyjoints into each block end, one on each side of the insulation.

above the wall along its length will be louvered and double glased window sections and architecturally the roof line should “float” over the heavy wall below.