The methods for measuring "floor space" vary depending on whether building features should or should not be included, such as exterior walls, internal walls, corridors, elevator shafts, staircases, and so on.... The method used by the Federal Housing Administration (FHA) to measure floor space for mortgage underwriting purposes is called the "Standard Flood Elevation." The FHA guidelines state that if a property has more than one level above ground, the office shall include the total area of all floors above grade. However, the FHA also states that certain areas will be excluded from this measurement: rooms less than 740 square feet (70 m2), bathrooms, and other spaces with clear boundaries... These measurements are important because some insurance companies may not cover properties with high-risk features. For example, some policies exclude apartments built after 1946 due to changes in building codes that require fire separation between buildings. In general, the closer together any two surfaces are, the higher the risk of injury if someone falls against them. This is true even if they are painted the same color. If there is no door handle or other safety device to prevent people from walking into dangerous areas, this increases the risk even more. Doorways with only wall space on both sides increase the danger even more because someone might walk through them thinking they are safe paths when they are not.