Used with permission from Working RE magazine, published by www.orep.org, providing E&O insurance for
appraisers, inspectors and other real estate professionals. (888) 347-5273 [email protected].
Editor’s Note: Appraiser Pat Butler shares little-known but common measuring mistakes,
reveals why two competent appraisers might produce varying sketch measurements and provides
the best ways to reconcile the differences.
Everything You Don’t Know about Measuring (Really)
By Patrick J. Butler
An important part of the appraisal review process performed by relocation companies
and others is ensuring that both appraisers submitting reports have calculated a mostly
similar amount of gross living area for the subject property.
Likewise, it’s important for every appraiser to understand why their sketches can vary
from other appraisers, even when both are done “by the book.”
A reviewer might need to determine whether an appraiser made a measuring mistake or
whether differences in each sketch are simply a result of different measuring
techniques. Insurance underwriters also reveal that measuring mistakes are one of the
most common reasons appraisers get sued.
This article will introduce you to some inherent problems in the measuring process, allowing you
to complete (or review) property sketches with an understanding of what problems might occur
when measuring a particular house.
Because many organizations require a fixed limit on how close two appraiser’s size calculations
must be- 100 square feet for example, accurately measuring properties becomes exceedingly
important. After reading this article, you may decide a relative amount, such as a five percent
difference, is a better strategy. To illustrate, a 100 square foot difference on a 2,000 square foot
home (five percent) makes sense but what about a 100 square foot difference on a 5,600 square
foot home?
Significance of Small Mistakes
Some of the measuring situations mentioned here may result in an appraiser being off on a
measurement by only a few inches and this does not seem like much. However, remember that a
house sketch might be comprised of dozens of small line segments, and those one- or two-inch
mistakes add up if they are all in one direction. Also, the gross living area of a house is
comprised of area calculations in which width measurements are multiplied by depth
measurements—multiplying the effect of any mistakes.
Finally, there are some appraisers who insist on rounding their measurements to the nearest six
inches or even a foot. A one-inch error can therefore result in a six-inch mistake if it causes the
appraiser to round up or down in the wrong direction. Now multiply that six-inch mistake by the
50-foot length of a sample house and suddenly that one-inch mistake just affected the living area
by 25 square feet. An appraiser who rounds to the nearest foot just made a 50-square-foot
mistake by being off on only one measurement out of dozens that are likely to be made.
Pulling your Tape Tightly
Fiberglass measuring tapes are probably the most common measuring tool in an appraiser’s
arsenal. Fiberglass models are preferable to steel tape models because they are less apt to scratch
something when pulled around inside a house. Fiberglass has a tendency to stretch more easily
than steel tape. Two people can get a different measurement depending on how tightly they pull
the tape.
The stretch is usually less than an inch but that can be a critical amount for an appraiser who
rounds his or her measurements to the nearest six-inch interval. Does one of your sketches have
measurements that are consistently shorter than the measurements of another appraisal? It could
simply be a difference in how tightly one appraiser is pulling his or her tape.
If this sort of difference in measuring has caused the sketches to differ quite a bit in their living areas, it
might be necessary to have one of the appraisers re-check his or her measurements. That might actually
require another trip to the subject property.You probably can get a good idea of which appraiser did a
better job measuring based on your interviews with them. That will help you decide who needs to be
encouraged to double-check his or her work.
Rolling Wheel
Some appraisers measure using a rolling wheel. These are commonly available with either small
or large wheel diameters. A smaller-wheeled model is better for measuring the exterior of a
house because it can be rolled in closer to an inside corner. Some of the larger-wheeled models
have a 12-inch diameter wheel and can be rolled only within six or seven inches of an inside
corner. A larger-wheeled model is more useful for taking long-distance site measurements over
rough terrain, where the larger wheel is less apt to slip as it is rolling.
When measuring a wall with an inside corner, the appraiser needs some sort of reference point
on the wheel itself to know when one revolution has been completed. The appraiser needs to
carefully line up the reference line over the corner of the house and make sure he or she
considers where the reference mark ends after the wheel has traveled the length of the wall. This
will allow the appraiser to measure the final distance between the reference mark and the inside
corner. Overall, rolling wheel measuring tools are among the least accurate devices available
because the diameter of the wheel reduces the ability to measure into tight corners.
Another error made with rolling wheels is when an appraiser rolls the device along the sloping
surface of the ground rather than against the house. In this instance, the appraiser actually is
measuring the slope line of the ground, which will be a longer distance compared with the actual
width of the house.
Carefully view the exterior photographs of the subject property to see if there are any sloping
areas that might have contributed to measuring errors. If you are comparing two appraisals with
differing amounts of living area, it might be a good idea to ask your appraisers what types of
measuring devices they used. The “wheel-roller” appraiser might want to double-check his or her
measurements using a fiberglass tape.
Lasers
Laser and ultrasonic tape measuring devices are becoming the measuring tools of choice for the
modern appraiser. Ultrasonic measuring devices are less expensive than laser tools and are
becoming more commonly used by appraisers. Ultrasonic devices rely on sound wave
transmissions through the air and measurements can be affected by changes in temperature.
Thus, two appraisers can acquire different measurements depending on the temperature of the
room they are in. The targeting beam of most ultrasonic devices can be large in diameter—that
can result in inaccurate measurements if it is unclear where the invisible beam hit.
Most of the ultrasonic devices are designed for the mass consumer market and are likely to have
quality issues. Many appraisers and real estate agents who use these devices will tell you that
they seem to become less accurate over time.
While expensive, laser measuring devices are the tool of choice for any appraiser desiring the
utmost accuracy. One popular model used by appraisers is the Disto by Leica. These devices
were used in the surveying profession long before they became popular with appraisers. As a
result, most laser devices have a rugged design and generally are a higher quality than ultrasonic
devices. Most laser measuring tools will project a red laser dot onto the target so the appraiser
knows exactly where he or she is measuring. Some even have built-in scopes so an appraiser can
visually line up the red laser dot over a long distance.
If an appraiser is properly using one of these laser tools to measure a house, you generally can
expect more accurate measurements compared with the other types of devices. If you are trying
to reconcile two sketches with different measurements, it would be a good idea to ask each
appraiser what tools they used to measure the house.
Trouble Spots
Some characteristics of a house can cause measuring problems. Appraisers are taught to measure
the outside dimensions of a house—that is where the term “gross” comes from in gross living
area. The exterior dimensions assist the appraiser in developing the cost approach when it is
needed. Of course, the cost approach is not required for a Worldwide ERC® appraisal but
appraisers still use the same measuring techniques.
Problems start to occur when the outside walls of a house have varying thicknesses of materials.
A common example is when a portion of the house has face brick installed on only the lower
portion of the wall. One appraiser may include the face brick when measuring while another may
not. Unfortunately, there are no standards indicating the correct way to measure a wall with
differing thicknesses.
If you compare two sketches and see that one appraiser has a wall length that is three to four
inches longer than the other appraiser, look at the photo of the house—if you see a wall partially
covered in face brick, then you will know the source of the difference between the two sketches.
Decorative stonework creates the same type of problem: large stones have differing thicknesses
that can easily cause two appraisers to be off from each other by four to six inches on one wall.
One of the best solutions to the differing wall thickness problem is for the appraiser to keep track
of how he or she has been accounting for differing thicknesses and change measuring methods
on opposing walls so that the overall thickness of a particular wall segment represents an average
thickness.
Lap siding can create another type of measuring problem. Lap siding is the horizontal siding on
a house where each subsequent board partially overlaps the one below it. If you look head-on at
the corners of a house with lap siding, they usually are tapered—that is, the top edge of one piece
of siding is narrower than its bottom edge. Two appraisers measuring the same end of lap siding
can obtain different measurements depending on where they attach their tape measures. It is
usually a good idea to attach the tape measure to the middle section of the siding to obtain an
overall average reading.
The corners of a house present another problem. Vinyl or aluminum siding have corner pieces
installed at every outside corner of the house; wood siding also can have similar corner pieces
installed. Those corner pieces usually add an inch or two to the length of the corresponding wall
section.
Some appraisers will include the thickness of the corner pieces while others will ignore it.
Sometimes those corner pieces will be installed rather loosely—it is imperative the appraiser pull
the tape measure especially tight so the corner piece is pulled tightly against the house. Look
carefully at the house photos to see if there are corner pieces installed or if the corners of the
house just have butt joints.
Not so Square
A new appraiser quickly realizes that many houses are not built square—this becomes most
apparent when the appraiser starts to draw the sketch on his or her computer. Suddenly, the
sketch does not “close” completely, despite the appraiser typing in all the correct measurements.
Few appraisers will draw a sketch that shows the reality of a crooked house—most appraisers
will fudge the sketch so the entire house comes out square. That has become an acceptable
solution to the problem—most appraisers square up their sketches.
Nonetheless, the practice does result in otherwise absolute measurements getting a little
distorted. Despite the best intentions during the measuring process, accuracy gets lowered as a
result of the appraiser squaring things up.
Sometimes an appraiser is simply unable to directly measure part of the exterior of a house. The
second story of a house can be troublesome if there are no good reference points to line up with
on the first story of the house. That can happen if there is a room or closet on the second level of
a house that is partially projected out over the first story of the house.
Some rooms may project out over the garage but not have a window on that particular wall,
leaving no visual reference on the exterior of the house. In that instance, the appraiser might have
to take interior measurements of the house and convert those into exterior measurements by
adding the wall thickness to the interior measurements. Walls commonly range from five to eight
inches thick. A problem occurs with this approach when it is difficult to measure the wall
thickness because of an uneven surface, such as a stone veneer.
Wall Thickness
Different appraisers are bound to get varying measurements for the average thickness of the
exterior wall of the house. Many high-end houses will have features such as walk-in closets or
bathrooms that blend into the outside elevation of the house. Pay particular attention to these
problem areas on a sketch and you likely will see some variation in measurements between
different appraisers.
“Gross Living Area (GLA) is the calculation of the total living area in the residence, expressed in
square footage. This is calculated using exterior measurements (except condominiums and
cooperatives), and is generally limited to the habitable above-grade living area only. Basement
and attic areas (finished and unfinished) are not included in GLA, room and bath counts.
However, they may make a valuable and significant contribution to the property value, and
should be calculated and shown separately in the report.” - Worldwide ERC® Guideline #5
from the Relocation Appraisal Guide
A decision has to be made when an appraiser starts to account for wall thicknesses: does the
appraiser only consider the exterior wall thickness or should he or she also consider interior wall
thicknesses when drawing an area of a house?
Let us take an open two-story foyer, for instance. The appraiser might take an interior depth
measurement toward the front of the house and then add the exterior wall thickness. Should the
appraiser also add any sort of wall thickness to the width of the open foyer where it does not run
against an outside wall?
There is no standard to apply when answering that question, so you might see two sketches of the
same foyer with different depths and widths. The issue of how the wall thickness is handled
lends itself to measuring inconsistencies and sketching difficulties. All you can do as a reviewer
is make sure that both appraisers are within a foot difference of each other.
Most appraisal sketching programs do not give appraisers much control over wall thicknesses.
Many simply draw a thin line and it is not apparent if the line represents the inside or outside of a
wall section. The appraiser lines up different levels of the house by drawing lines on top of each
other but it is not exactly clear whether the interior or exterior of the wall is being lined up. That
is in contrast to computer-aided design (CAD) programs that do take the wall thicknesses into
consideration and allow the user to precisely line up the appropriate areas. An appraiser wanting
the utmost accuracy with his or her sketch might be hampered by his or her sketching software.
The Unit
An appraiser has to make a decision on what unit of measurement is going to be used in
measuring a house. Is a common fractional measurement system (sixteenths of an inch) going to
be used or are all measurements going to be taken in tenths of an inch? Most sketching programs
allow data entry in either method but rounding errors will occur if the appraiser enters
dimensions in a unit other than what is being used in the sketch program.
For example, it is obvious that six inches equals exactly half a foot. But what happens when an
appraiser needs to draw an eight-inch line on the sketch? An eight-inch line is about 0.667 feet,
but most sketch programs do not retain that many significant digits. So eight inches might get
converted into 0.7 feet. The measurement has been slightly changed as a result of the conversion
process.
Conventional tape measures are available in tenths and most electronic measuring devices also
allow for changing the units. The appraiser should be recording measurements in the same unit
that is going to be used when sketching. There are quite a few appraisers doing sketches to the
tenth of an inch who are using conventional tape measures that only allow fractional
measurements.
Standards
ANSI Z765-2003 is the American National Standard Institute (ANSI) standard that covers the
measuring process and is available from the National Association of Home Builders (NAHB)
Research Center at www.nahbrc.org. Unfortunately, it does not address the majority of issues
mentioned in this article. It does provide a bit of clarification on how to properly measure an
open area such as a two-story foyer and when to include small areas such as walk-in closets. It
requires that any openings to the floor below not be included as finished square footage.
However, the appraiser can include the area of the stairs themselves.
You never can be sure if any two appraisers are following the same standard because adherence
to the ANSI standard is voluntary. However, the Worldwide ERC® Relocation Appraisal Guide
contains its own definition of gross living area that appraisers must adhere to for providing
standardization. It is very similar to the ANSI standard in that it requires exterior measurements
of the above-grade habitable areas.
Basement and attic areas are not included in the calculation of gross living area. However, those
areas might contribute to value and can be given value elsewhere in the appraisal report. Open
areas of a house, such as two-story foyers, are not considered habitable areas, so they would not
be included as part of the gross living area calculations.
Appraisal Effect
The most obvious effect of differing measurements on an appraisal is that any adjustments for
gross living area might differ among appraisers. That is why some appraisers do not even make
an adjustment on a comparable unless it differs by at least 100 square feet. An appraiser who
adjusts for very small differences in gross living area should be questioned as to his or her
technique.
Differences in measuring also can affect comparable properties. Appraisers need to do their own
reconciling when looking at comparable property data. For example, an appraiser might use
comparable properties of the exact same model as the subject property, while the assessor might
report slightly different measurements and calculations.
The appraiser should obtain the assessor’s actual data cards for the comparable properties and
check for him- or herself where problems occur. The appraiser can report the assessor’s figures
that are different but choose to make no adjustments if he or she is certain it is the exact same
house. The appraiser should comment in the report that the houses are the same despite having
differing amounts of gross living area and that is why no adjustments are required.
The attention paid to some of the subtleties of measuring techniques reported in this article might
seem a bit over the top. But every appraiser measuring a house should be considering these
factors when encountering a difficult measuring situation. A property sketch that appears simple
on the surface might be the result of an appraiser making lots of small decisions on which way to
proceed.
Summary
Clearly, there are many measuring difficulties for which the appraisal profession has no agreedon solutions. When reviewing, it is important for you to interview your appraisers to see how
they handled particular situations.
Make sure they use the highest quality measuring devices appropriate for the job. Ask whether
they considered the wall thickness of the house for any of the measurements. Ask whether they
obtained data cards from the assessor to double-check the assessor’s work for comparable
properties. Find out if they used supplemental data such as builder’s marketing sketches to
further verify some of their data. Look at the photos of the subject property when reviewing the
sketches and talking to your appraisers—see if the dimensions on the sketch have obviously been
rounded to a large interval such as six inches.
The answers to those questions will help you determine if your appraisers made obvious
measuring mistakes or just used different techniques. If there are no obvious measuring or
sketching mistakes, then both of the sketches should be reasonably close in their gross living area
calculations. There are no standards as to how far apart two different sketches may be—however,
I would recommend that you be concerned if two appraisals differ by more than five percent in
gross living area.
Reprinted with permission of Worldwide ERC®, from the May 2006 issue of MOBILITY.
About the Author
Patrick J. Butler is with Appraisal Services, Inc., Montgomery , IL . He can be reached at (630)
897-2088 or [email protected].