I have a long-term plan to build an ecohome, and need some advice. It'll be many years before I'm in a position to start building, partly because I want to think through my ideas properly so I'm sure they'll work. I've already decided on how I'll build the walls, for example: they'll be cob (primary internal, doubling as thermal mass for a rocket mass heater) wood frame with bale infill (external, for insulation) and wattle & daub (secondary internal, to save space) finished in lime render.
I get insomnia when the nights are hot, humid and short, i.e. for about 3 months each summer, so I'm thinking of having the main bedroom half underground; the bottom of the window will be resting on the stone plinth I'll be using for the straw bales & cob (local stone, so it's easier to get planning permission - and because the local stone is a gorgeous dark honey colour). This should mean the bedroom will stay cool all year round; I'll be putting a cellar next to it for the same reason. The soil will probably be mainly clay, which is another reason for digging down: the clay removed while excavating the bedroom & cellar will be used for the cob; the topsoil will be reserved for the roof.
I have two main questions. Firstly, what is the best way of building the retaining walls for the semi-subterranean section? They'll need to support the weight of the stone plinths and, in one case, the cob wall, plus the roof. Secondly, what kind of drainage system (if any) will I need to use, or will a good damp-proof course be sufficient?
sorry i dont have much time just now but if you're intrested (or any one else ) in techniques used in morocco for earth building, check on youtube for 'coffrage' or 'briques en terre maroc' and if you're more intrested i can develop on these, and the hybrid part would be using cement.