When measuring Do you:
- Deduct 6 inches for brick facades or use measurements from the interior or exterior?
- Round to the nearest inch, 1/4 foot, 1/2 foot, foot?
- Eliminate one level of the stairway and open spaces?
It all adds up (or down) and when it comes down to it, it's all about how the county or developer (or whatever reference you are using for the houses in the area) has decided to measure the comparable property spaces. Even my state board has varying opinions within the office. This is the reason I give a 50 square foot leeway for comparable properties to subject.
Here are some ANSI (American National Standards Institute) 'suggestions'. I say suggestions because it is a voluntary guide rather than a direct rule.Always start by measuring the outside of the house.
- Begin measuring from any corner and work your way around the house. Move counter-clockwise so the numbers on your tape will be right-side-up.
- Measure the exterior of the house to the nearest inch or tenth of an inch. Measure from the exterior face of the walls. Include any features that are on the same level as the floor, such as chimneys and bay windows. Do not include the thickness of any corner trim pieces or greenhouse windows that don't have a corresponding floor level. * Use the 100-foot tape for long wall sections and the 25-foot tape for short sections.
- If there are stairs, include them on every level they serve.
- When there are openings to the floor below, subtract the opening from that level.
- For split-level designs, measure each level. You can lump multiple floor surfaces into one level if they are within two feet of each other.
- Exclude any areas, such as porches and converted garages, that are not finished or heated the same as the rest of the house.
The ANSI standards make a strong distinction between above-grade and below-grade floor area. The above-grade floor area is the sum of all finished square footage which is entirely above ground level. The below-grade floor area includes spaces which are wholly or partly below ground level.
Level ceilings must be at least 7 feet high, and at least 6 feet 4 inches under beams, ducts and other obstructions. There is no height restriction under stairs. If a room has a sloped ceiling, at least one-half of the finished floor area must have a ceiling height of at least 7 feet. Otherwise, omit the entire room from the floor area calculations. If a room with a sloped ceiling meets the one-half-of-floor-area-over-7-feet requirement, then include all the floor space with a ceiling height over 5 feet.
Detached Rooms, Guest Quarters
According to the ANSI standards, finished areas which are not connected to the main residence by a finished hall or stairway must be listed separately. If you have to leave the house to get to the room, it's not part of the finished floor area.
I realize there's a bit more than just measurement information in there, but I found some of the 'standards' interesting and perhaps useful in the future. Although ANSI is not 'the law', it is the closest thing I could find to it. I will have to assume that developers, tax assessors and other 'measuring professionals' use the ANSI guide and measure likewise (although not necessarily going counter-clockwise everytime).