The Dwarf Walls

Once the footings had gone off we were ready to form up the dwarf walls.

These are 300mm wide and 300mm high concrete beams which would become the base from which the rammed earth walls would rise.

We did this in 2 stages - the inner walls (seen here) first to avoid dragging the weighty concrete hose across formwork.

Room Services

The electrical, water and waste services were all underground so their conduits had been brought in through the footings.

The phone (top conduit) had to enter the building above ground so that Telstra could mount a anti-spike box on the building, it's conduit had to exit through the formwork.

The electricity supply was to arrive underground and it's conduits had been started through the footings and continued vertically - its bent over here so that the conduits would emerge roughly at the centre of the top of the dwarf wall.

The plumbing would remain under floor but the electricity and phone needed to come up through the walls so their conduits had to travel through the dwarf walls.

Details

A stirrup wired in place awaiting the concrete.
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An indent to key the walls together

The outer dwarf walls

The inner walls were poured and vibrated for extra strength.

Here they are curing - we left the plastic form-lining in situ and used it to retard the drying-out of the walls to maximize their strength.

That looks better

By the time we were ready to pour the outer walls the inner ones were ready to be unveiled and they do look much better without the plastic.

You can tell where the doorways are going to be by the lower sections in the inner walls.

Concrete “homeopathy”

Another last-minute change was inserting a line of granite slabs against the external wall of the formwork.

This served 2 purposes - a decorative feature for the external walls as well as a way of teaching the concrete dwarf wall to become like granite.

It has no science-based evidence to support this notion, but - like many features of the building - it seemed like a good idea at the time.

Certainly the cement in the outer wall is extremely hard and is not as easily chiseled or drilled as other sections.

The final wall-pour

The council had insisted we use cyclone rods imbedded in the dwarf walls to tie down the top plate on the top of the earth walls which further complicated the preparations for pouring the walls.

This is what the walls looked like after they had been vibrated and before they had been screeded.

The vibrating was so effective in one place that the formwork expanded due to the pressure of the wet concrete - there was nothing we could do to fix that and so there is still one dwarf wall which juts out from the base of the earth wall.

The Dwarf Walls completed

Ready for the earth

The last step in the dwarf wall preparation was to ensure that moisture could not travel up through the concrete and seep into the earth walls.

I didn't feel happy with assurances that this was “unlikely” and so we added a layer of bituminised felt to the top of the concrete and sealed all the openings with black jack - a waterproof bitumen compound.