Conceptual sketches

Kyle and I have been through 3 different engineers so far, and we think we've finally found the right one. We wanted someone with a bit of imagination of their own (rather than simply ticking boxes), who was a little excited about the unusual nature of our project (rather than daunted by it), who was willing to work with us as a team, and seemed to understand our vision for the property.

Previously we were looking at something based off the Arc House, designed by Owen Geiger, however given the wind at the site flat roofs were becoming more complicated and technical than we were willing to deal with and we've returned to something more like the Enviro Dome below:

To assist in communicating the vision, I'd done some conceptual sketches of our intended house, focussing not only on the internal layout but also the features I thought an engineer would need to be involved with.

Firstly, the vision for the future:

We imagine building the 3 domes of the house first, with small butresses to either side to act as a retaining wall on the berm. A little while down the track we'll add an outdoor covered area a little way off the house, again bermed by necessity because of the hill. This may or may not end up as a place for our cats to roam (enclosed) outside, as they are strictly indoor animals. Someday much further down the track, we want the option to extend the house off the other side if the mood takes us.

Bermed earth-walled structures make a lot of people nervous (even in spite of the whole earthship thing). Water is the first question to come up, so we wanted to have an answer (or at least the start of one) ready.

It seemed to me to be a no-brainer that the goal would be to avoid any water ever getting close to the waterproof membrane, so we'd need a drainage system.

It also brings up the question of ventillation. In a house like this, ventillation is another way of regulating temperature. The berm makes earth-tubes seem like a straight-forward idea, with the hillside allowing us to vent them downhill meaning we won't have the problems with moisture build-up and mould that plagued the early PassiveHaus models.

The exact point at which the earthtubes exit the hillside doesn't really matter at this stage, so I just drew curvy lines.

Finally, earthen buildings in wet parts of the world need a 'big hat'. I explored a lot of different ideas for roofing, and finally ended up with something pretty simple but hopefully functional.

I wasn't sure about insulation - seems a bit counter productive. On one hand it would keep any warm generated inside in in winter, but it would also stop the sun heating up the mass of the roof. I'm not convinced it would work out in our favour, and the engineer agreed. However, Council authorities like to see mundane, regular things like insulation when they approve Development Applications. We'll see how that one pans out, but I think we'll be good as it's usual for rammed earth structures not to have insulation in the walls.

I'd also done a drawing of the internal layout, on graph paper to make it more accurate for size:

Later on, however, I realised that we'd have to switch it around a little as the bathroom and kitchen can't be directly connected, but we want to retain that orientation for the kitchen/laundry so we can have morning sun in the kitchen.

The engineer we've chosen seems keen on all fronts, nothing is an obstacle just a technicality to figure out. We like this approach!