## What is Head ?

**Definition of Head in Construction**

There are two different, common definitions of the term ” head ” in construction. This term can reference the top of a window or door as the head or it can be the amount of water accumulated in a vertical column. In hydraulics the term head is used when sizing pumps and hydraulic equipment.

The amount of head is directly associated with pressure. If a retaining wall has accumulated a head of water against the backside of the retaining wall, substantial pressure will develop on the wall. Dependent upon the design of the wall, as well as its capacity to drain the water from the backside, will determine the ability of the wall to sustain the pressure without failure. Water has a tremendous influence on the design of retaining walls, slabs on grade and other structural components. The forces that develop when a head of water develops can cause substantial damage. The weight of water is approximately 8 pounds per gallon or 64 pounds per cubic foot of water. Due to the fluidity of water, cubic foot of water will exert the full 64 pounds of lateral pressure on a structure. The calculations of water pressure is extremely important , due to this force.