How Big is My House?

House measurement square footage

As a house gets older the wood begins to shrink…

Do you ever get those questions? “Well ABC appraised my house last year and my house was 3,726 square feet. Why do you say it only contains 3,698 square feet?”. I have always wanted to say, well as your house gets older, the wood begins to shrink… Everyone knows of course that houses come in different sizes, shapes and that walls can be built at angles other than 90, 60 or 45 degrees, thus accurate measuring can be a challenge. When you factor in roof pitch for upstairs rooms, or many shrubs, or rose bushes or other obstacles around the perimeter, any given measurement can be off by a few inches one way or another and then you take the variance of a few inches and multiply that by a run of 45 feet or more. The estimated house size can easily vary due to the different methods that are used to measure the home as well.

Many old timers, like me, still use a 100′ steel tape to measure the exterior perimeter of the home. There are, of course, several alternatives available today:  steel, fiberglass, and vinyl measuring tapes. There are also measuring wheels, and sonic and laser measuring aids. There is no one device that is better or more reliable. However, you must understand the degree of reliability that each device offers before you decide to use it to determine size. For instance, the measuring wheel can skip when it encounters rough terrain. The sonic device may give false readings if there is an obstacle between you and the wall that you are measuring. The laser sight can find interference from direct sunlight, or can give false readings if an obstacle is blocking a clear path between you and the distance you are attempting to measure. A vinyl tape will stretch over time thus 1 inch becomes more than an inch. A steel tape requires maintenancemost reliable, in my humble opinion.

When measuring a home, the garage, porch, patios, and any non-heated or cooled space is not included in gross living area; however, these spaces are measured so that the appraiser can account for the cost of these items. Additional flatwork, or extra concrete (i.e. driveways, parking pads and the like are also measured for the cost approach). Finished attics can be included if properly finished, including venting for heating/cooling. The pitch of the roof can inhibit the space which is counted due to clear space (overhead). Generally speaking, any space below 3′ is not considered habitable space. Also when measuring a second floor, many appraisers will measure the interior walls of each room and add the space together. This is practical for a small condominium or other type dwelling that does not have a lot of space; however, it is not a practical approach because interior walls should be included in the GLA. In other words a 12 x 12 bedroom right next to a 12 x 12 bedroom (i.e. 144sf + 100sf) will not equal 288 square feet of gross living area. Why? Because there is a 5-1/2 inch wall in between the rooms and exterior walls on each side of the room. Therefore, this span is actually 25.37 x 12 or 304 square feet. How can this space be added to gross living area? I have been asked this time and time again. Let me ask a question though. When a home is built, do you believe these walls are simply built without cost? Of course there is a cost, and the only proper way to account for cost is to include the space at the time of measuring.

The accepted method of measuring a home is the ANSI method; however, there is no law that requires an appraiser to use this method. The law, USPAP, requires that an appraiser communicate the appraisal report in a way that is not misleading; thus as long as the sketch is presented in a way that is easy to follow, and the dimensions that are presented are reasonably accurate, the appraiser has met the intent or spirit of the law.

Keeping in mind the variables that can come into play when measuring a house, it is understandable why no two appraisers are likely to arrive at the same square footage estimate unless the house is a basic shape, with no angles, no fences, no shrubs and no pets. Any of the oddities or variables can cause appraisers to write different findings, and different findings will cause different results.

All of this being said, appraisers should be able to agree within 10% of size each and every time. If a sketch is off by more than 10%, there is a distinct possibility that someone is in error.

By John Reynolds aka UncleZev ~ Source Appraisers Speak Out

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6 Responses

  1. Avatar Joe says:

    Any appraiser who is measuring to the 0.1 inch (ANSI) is insane and needs to have his head examined.

    And you are actually worried that a vinyl tape may stretch. Are you kidding me?

    Driveways and parking pads are measured? By whom?

    • Avatar Richard says:

      I believe ANSI is 1/10th FOOT not INCH. You might want to read the standard before suggesting head examination.

      Vinyl does stretch, metal does rust and break. Author is correct, fiberglass is preferred.

      I don’t typically measure driveways either, but in the case of a 10,000 sq.ft. drive with pavers (think Gulf front mansion on Florida beach), underwriter would expect measurements to support the $60,000+ item in my cost approach.

  2. Retired Appraiser Retired Appraiser says:

    Submit $800 to your local bank ($400 for the bank/$400 for the appraiser) and someone will tell you.

    Appraisers are unable to comment on valuation these days without the necessary kickback you see.

  3. Baggins Baggins says:

    John, I liked that article. Good read. Yeah, my favorite vinyl tape measure had stretched over the years. Had to quit using it because the results would be sometimes off by a half foot on a long measuring stretch. One day I used that old 100′ steel tape and figured out why my sketch power seemed to be dwindling. The steel tape is the best, but it is unruly to work with for tough measurements. / I like to put this comment in my sketch, to help remind people why it’s a mandated inclusion; “The sketch serves it’s intended purpose of verifying the county stated sq ft of the subject is generally accurate.” Sometimes also making a statement if the sketch came together well, or was difficult. / I count the inches, every one of them. It’s not always perfect, but the purpose is to seek validation of existing data points for proper credible comparisons. Every now and then, you find one with incorrect city records, sometimes substantially. Sizing verification is a very important aspect of appraisal. You try to be as accurate as possible. My sketches are pretty simplistic and I’m not a great sketch artist. The emphasis is on proper size and room count, for vital comparative points. Listing agents can change that number at will, depending on how the mls is set up. At least a general verification of proper size is a vital consideration point.

  4. Mike Ford Mike Ford says:

    Good comments John. I think the actual FHA standard for finished attic living area height is 5′, but 3 feet for legitimate second stories seems more reasonable to me, when coupled with photos that show the interior roof pitch-often on only one side.

    Joe above apparently miss-read the ANSI standard. Its 1/10th of a foot OR one inch, depending on the type of tapes used, NOT 0.1 inch. Also he must be new if he is unaware if fiberglass tape stretch. Its easily an inch over a 100 foot run. If all one appraises are 25 foot long houses, maybe its not much of a factor, but its something one should be aware of.

    Many assessors and building departments consider porches or entry stoops under the main roof in their building size estimates. It’s common for these ‘cut outs’ to account for minor size discrepancies.

  5. Avatar Jack Schlenk says:

    In the comment section(s) of my appraisal report(s) I note the subject physical measurement(s) GLA, also the Assessor GLA, the Realist GLA and the MLS GLA. Note in some cases each of the above measurement are different. I explain to the report reader why I used the physical measurement GLA.
    When I get the call “why is the Assessor GLA different from the report GLA”. I request the party asking to please review the data in the comments section of the report.


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How Big is My House?

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