The effect of forces

These forces (live loads, dead loads and wind loads) acting on buildings can cause walls to deform (known as 'racking') and/or increase the tendency to slide.

Three diagrams show effects of various forces on houses, namely a tendency to slide and rack (walls deform) because of forces acting horizontally on the external walls, and uplift (connection failure) by forces acting upwards on the roof. Sliding and uplift are resisted by tie-down connections. To resist racking forces, bracing is required.