To address the problem of rainwater for the timber structure, we have covered it with a sloping mental deck. A wooden floor is floated above this with timber battens, allowing rainwater to fall away from away from the house and timber.
A simple energy-calculation gives us energy estimates for various material choices. Using these estimates, we can choose the most efficient materials. We have used OSB as the structure, with cork being used for insulation. The structure is clad in cedar, a weather-resistant softwood.