Foundation (engineering)
Foundations are designed to have an adequate load capacity depending on the type of subsoil/rock supporting the foundation by a geotechnical engineer, and the footing itself may be designed structurally by a structural engineer. The primary design concerns are settlement and bearing capacity. When considering settlement, total settlement and differential settlement is normally considered. Differential settlement is when one part of a foundation settles more than another part. This can cause problems to the structure which the foundation is supporting. Expansive clay soils can also cause problems.
Bush carpentry
Ron Edwards asserts that no training at all is required. The requisites are 'a calm mind, reasonable health, and a willingness to learn'. Edwards points out that the early settlers built their homes without prior knowledge and experience, and 'many of these buildings are still in existence a century later'. Edwards adds, 'Confidence in your own ability is the first requirement ... the second is access to knowledge.'