Making Sense of Square-Foot Figures

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SPECIAL TO THE TIMES; Katherine Salant is a syndicated real estate columnist who writes about newly built homes

Most advertisements for new homes indicate the size by the number of rooms. The number of square feet--a figure that most buyers also use when assessing house size--is rarely mentioned. Even in sales brochures given out at model houses, the square-foot figure is not routinely given. Why not?

The home building industry has not had a standard method for calculating square feet. And builders, knowing that buyers are comparing them on this basis, are understandably shy about giving a square-foot figure when this is routinely calculated in so many different ways.

For example, some builders include all the walls in the square-foot calculation. In a two-story center hall Colonial that is billed as 1,800 square feet, as many as 200 square feet can be walls.


Some builders count only what you can walk on, excluding walls and closets.

Some double count two-story spaces, meaning that they calculate the space on one floor, then double it. If the two-story space is an entry foyer, this doesn’t add much, but when the two-story space is large--say a family room or a great room--double counting can seriously inflate the size of the house.

Home builders are not the only ones in the industry that have not established a standard for calculating square feet. Architects, who apply a single standard to all types of construction, say their method is too cumbersome for residential buildings.

Real estate appraisers have a standard convention, but builders don’t use it. Real estate agents have their own method, which differs from the others.

Help is on the way, however. Recognizing the problem, the National Assn. of Home Builders commissioned its research center to establish a standard. The center, in turn, organized a committee made up of major players in the residential construction industry--builders, architects, manufacturers, appraisers, real estate agents, homeowners, mortgage lenders and several agencies of the federal government.

The committee drafted a standard that has been accepted by the American National Standards Institute as ANSI Z765-1996. The institute acts both as a referee for any organization that wants to form a voluntary standard and as a repository for voluntary standards an organization develops. Its standards cover everything from the dimensions of a square foot to silver levels on photographic film.

The square-foot standard applies to only detached single-family and attached town houses; it does not cover multifamily structures such as condos or apartments. It is also limited to overall dimensions; it does not cover interior dimensions of rooms, which are typically measured from interior wall to interior wall. But it does give figures that buyers can use to compare builders.


The major distinctions are “finished” or “unfinished” and “above grade” or “below grade.”

A “finished” area is defined as “an enclosed area that is suitable for year round use.” The finished calculation also includes all walls, both interior and exterior.

An “unfinished” area has yet to be specifically defined. At present it is construed as an unfinished basement or garage, said Mark Gibson, a staff economist at the home builders’ research center who served on the committee that drafted the standard.

“Above grade” includes all floor levels that are entirely above the ground. “Below grade” includes all floor levels that are partly or entirely below the ground. A “below grade” classification can be given to an entire house--making it sound as if it were one big basement--if the house is built into a hillside, a common condition in some areas of California.

The standard also makes distinctions in ceiling height. To be included in the finished area at all, the ceiling height must be at least 7 feet; two-story spaces are counted only once. If the ceiling is sloped, at least half of the area under it must have a ceiling height of 7 feet; areas under a sloping roof with a ceiling height less than 5 feet are not counted.

The ceiling height issue comes up most frequently with 1 1/2-story Cape Cod-type houses. On the second story in some of them, the ceiling height is only 4 feet where the wall meets the roof.

How soon will the standard become widely used by home builders throughout the country? Gibson said that it has been endorsed by the home builders association and that many local building associations and individual builders have contacted him about it.


The Federal National Mortgage Assn. (Fannie Mae) and the Federal Home Loan Mortgage Corp. (Freddie Mac), leaders in the secondary mortgage market, and the National Assn. of Realtors have also expressed an interest, Gibson said.

Until it does become the standard, however, buyers will still have to ask individual builders how they calculated their square-foot figures, bearing in mind that there can be confusion even within a single company.

When the standard becomes widely used, buyers should be careful how they use the information. Comparing houses on a cost-per-square-foot basis, which many buyers do, can be misleading. A lower cost per square foot does not necessarily mean a better deal. Builder A may use materials that are less expensive but inferior in quality to those used by Builder B.

For a copy of the standard, call the builders association’s research center in Upper Marlboro, Md., (301) 249-4000.