I used a program called 'Home Plan Pro' to design the house - it is sometimes a little awkward to use but given its low cost I can't complain.
The external walls are 200mm concrete block with reinforcing bar every meter or so. The drain for black water goes to the septic tank and for grey water from the showers and washing machine to a soak away that runs along side some oleander bushes - no need to water them!
In the background you can see the new water deposit (16,000 litres more or less), the grey door on the left is the new boiler room - you can see the 3 solar hot water panels on the roof above, set at winter angle for maximum heat - these are linked into the central heating system along with the (also visible) home made heat pump. The orange marks on the wall are for 2 new connecting doors, the small door is obsolete and has been removed.
Everything here is built from concrete and steel, very little wood as it is expensive and tends to get eaten by the local bug population. It amazed me how much steel we ended up putting in the roof - see the image. It took 4 of us 2 days to prepare it for its concrete. We then used 14 cubic metres of concrete to give an approximately 6cm thickness. The hole at bottom left is for a wood burner chimney. There is also a hole for a roof ladder so all the roof space can be used for storage, something the Spanish don't typically do.
Acuario