During the early construction phase, freeboard is the elevation of a building's lowest floor to a height above the minimal base flood elevation (BFE). A freeboard mandate, with height limitations based on zone or level of danger, can be introduced to a municipality's regulations. Otherwise referred to as minimum clear height or MCV. Freeboard is important because it allows for emergency response equipment access without endangering responders. In addition, it gives occupants a sense of security since anything that happens below the freeboard level will not affect them. Generally, the freeboard should be high enough to allow for adequate fire protection and life safety facilities such as fire exits and escape routes that are clearly marked. The freeboard should also provide sufficient clearance beneath it so that any malfunctioning fire equipment does not hit the floorboards or other hazards that may cause damage or injure people if they fall. The freeboard must be determined during the design phase of construction for buildings over 7 feet tall, including residential high-rises. For lower-rise buildings, the freeboard can be estimated by adding 2 inches for every 10 feet increase in building height. However, this estimate is only an approximation since higher floors may have different loading conditions than lower ones and thus require thicker walls. As a rule of thumb, freeboard should be at least 1 foot for low-rise buildings and 2 feet for high-rises.