The Problem of Square Footage

Square Footage - What is it good for

You see it on every house listing website you look at it, in big, bold numbers. It's often one of the metrics people most search by,  and people use it as a common gauge to see if a property will better fit you. Some sites even have a price per square footage number, a seeming concrete analytics number to better compare two properties. But, where do these numbers even come from? How accurate are they?

So, Who's Counting?

You would think there would be a standard way that all trades would measure the size of a house. And while there is a standard, not all trades hold to it as firmly as others may. The problem comes in that there are so many different trades that deal with the size of a house. Each of them actually have a different goal for measuring, and therefore different needs for specificities and different accuracies. Here are some of the trades and their goals:

Developer:

Goals:

Usually, to sell a house, or to give a proper price of the work per square foot for budgeting and estimated sale purposes.

Methodology:

The problem here comes with the way the way some elements are typically omitted from the size of a house, but still need to be constructed, so to give a proper "price/sq. ft.",  especially if they are in a bidding process against another vendor, they may use different definitions. Some developers have been known to include unfinished areas, garages, balconies, and other elements in their square footage definition due to this, or the budget for built square footage could be taken by some as the actual square footage even if it is not included by the official standard. Some other developers would debate on whether to include siding or not. Again, there are many factors to be taken into consideration, as there are a lot of costs for building that inlude areas not officially counted in the standard, so numbers used here may not apply to other trades.

Real Estate Agent:

Goals:

To accurately give a proper idea of what the living space of a house is, and to give proper market comparison for pricing evaluation against similar homes.

Methodology:

Due to the goal to give an idea of what space in the house could be used to live in, some agents will just take the room sizes and add them all up to find the living area. Others use the ANSI standard to determine the size, which are taken from the exterior of the house, but which has very specific definitions of what can be included. And yet others use a modified version of the ANSI standard to better comply with a former unofficial industry standard (the difference is that the ANSI standard will include stairs on both the floors they lead to and from, whereas the unofficial standard only included the stairs once). Since the goal here is to better judge the usable square footage, the fact that things like block walls can add a significant amount of unusable space may cause some agents to prefer alternate methods of judging the size of a house.

Appraiser:

Goals:

An appraiser is most concerned with the comparable value of a home to other homes, but take in a lot of factors more than just the size of the square footage to determine that value.

Methodology:

 A lot of appraisers will go with the ANSI standard, but others will simply use exterior measurements to determine the interior space. That would include rooms with vaulted ceilings twice, sometimes include garages, and likely omit finished basements.

Tax Assessor:

Goals:

The tax assessor is mostly concerned with values for tax purposes, so they are a little less accurate since they are 

Methodology:

Assessors almost never include the basement in the square footage, and due to lack of access to the home, will often measure the exterior, then deduct a set percentage for the interior of the house (for example, 5% or 10%). 

Public Records:

Goals:

To give access for relatively easy access to information about the different properties, so many different trades and needs can have access to the basic information they need.

Methodology:

These records can come from just about any source, and depending on the age of the home, can be all over the place with regard to accuracy due to the methodology used and how updated it is.

Holding To A Standard

In 1996, ANSI published a standard for the measuring of single family homes, which was most recently revised in 2003, ANSI Z765-2003. This was created to more properly align all the measurement systems that were in place, and to make sure that there were actually comparable methods for the calculations.

However, since the standard is relatively new (in terms of how old houses and public records can be in many areas), this presents a problem that many houses will have inaccurate public records. Additionally, some don't even follow the standard, so the numbers can be even more skewed as it is not mandatory, and some realtors won't even list the square footage of a house just because of liability concerns. Also, many won't even measure the size of a house, and just rely on public records, so there is a problem of information not being updated.

On top of this, since there is so much confusion, many MLS sites have many different names for the size of a house, from square footage, to livable area, and often give options for many more. It is well established that the methodology can in many cases be very confusing, and the consensus is not firmly set.

The Art of Science

On top of the fact that some don't follow the standard and that many houses have not been updated to it, also, even within the framework of a standard, there is also an art to interpreting and measuring within a standard. Additionally, there are questions of precision. Rolling measuring wheels can be imprecise, tape measures can bow (especially the long 100' tapes), and sometimes you really just can't measure the top floor outside. With the advent of lasers, some of these concerns have been lessened, and even with them, there was still a reasonable amount of flexibility, as you can only have a certain factor of realistic precision. On top of that, some houses come close to the standard and different people may choose to add or deduct things that are very close. For example, if the standard says the room has to average out to 7 feet, and it comes out to 6'-11-1/2", then most people would tend to let that room slide. However, some people hold firmly to the standard. Also, what if a room has 3 walls and a floor finished, but there is one wall that isn't? If the majority is finished, is it still "similar" to the rest of the house? This can add to a judgement call for the person making the measurements. Therefore, even within the standard, there is some wiggle room of interpretation.

Significant Digits

This is where you have to choose what criteria are important to you, and where you start having to take numbers with a grain of salt, understanding that square footage is not necesarily the best variable, and that it is not as cut and dry a number as it may be thought of. For objective analysis, it's best to minimize the importance of your dependence on that value, as with any method of evaluation, bad data can lead to incorrect beliefs. This is compounded when you know who measured one house, but not who measured a different house. A range of 5-10% of difference in size is not out of the question, and tolerances need to be taken into account.

This is also where most people should realize that size isn't necesarily the most important number for comparison. Number of rooms, their sizes, how the house flows, and many other considerations should be much more important for evaluating a house. This is where having a floor plan, and not just pictures, as well as accurate measurements, can give you a much better concept of a house, and how it might best fit your needs.

So, Now What?

Don't view the square footage as more than a minor consideration to be used to give gross approximations, and don't buy into the "price/square feet" lie that some sites propose. Instead, see if a house fits your needs, and get someone who knows the standard to do any evaluations that you may need, since you will know at least the information you have is accurate. Additionally, it is best to also get a floor plan of any houses you are considering, if available, and there are often local companies who can assist you with this at a very reasonable price. That way, you know you are making the best informed decision you can.