A residential structural review most generally is concerned with a detailed visual examination of the building's foundation and visible cracks, bowing, or displacement as a result of current or previous differential vertical settlement, excessive horizontal soil forces, hydrostatic pressures, improper construction techniques, or other influences that distort the original alignment and may affect the primary (support) function or secondary (moisture penetration prevention) function. Other structural reviews may be concerns with "street creep", hillside subsidence, driveway or patio displacement, deck problems, sagging roofs and truss disconnects or joist and beam potential failures.