One of the first things people ask when considering building a straw bale house is, "Will I be able to get home insurance for it and will I be able to get a mortgage?" Due to the fact that this method of building is relatively new to modern construction, you may find it harder to find home insurance and mortgage companies willing to lend to you. However, If you are building a house that doesn’t use the straw bales structually but uses them as in-fill for say a timber frame building you should have far fewer problems.
If you want a truly ecological, environmentally friendly and low impact house it is hard to beat a straw bale house. Straw bales are available locally reducing transport and storgage costs and they offer fantastic thermal insulation values with virtually no impact on the environment. There are however some downsides, as with any building methods. Probably the biggest issue that affects most people is the thickness of the finished walls, a lot of internal room sizes may have to be compromised. A typical straw bale is around 500mm wide, once you add the external render and internal plaster walls can be 600-700mm thick.
Apart from structural stability the number one concern when building with straw bales is moisture. The bales must be kept dry while you are building and the floor, roof and wall coverings must keep the straw dry once the building is complete. A good damp-proof and decent overhang on the roof together with breathable render, plaster and paint should stop the water from getting in and allow any that does get through to escape.