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Drawing a sketch and measuring GLA

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Larry Lyke

Senior Member
Feb 2, 2002
terr --

I draw the sketch the first thing when I get back to the office for each inspection. I usually fill in the partitions and exterior doors plus enough text to make the sketch pleasant to look at and readable. I also add porches, patios, etc.

To measure for GLA, I measure the exteior of the home on the main level. While at each face of the home I attend to the upper stories. A partial upper story has rules which you can learn from this forum by searching. There's simply no reason for guessing. Sometimes, it's just plane Geometry. I would say that my sketches are within 1% accuracy.

Upper stories don't need to be measured from the outside. Just use geometry. Works perfectly every time. Or buy yourself a book of applied mathematic containing the elementary stuff -- that's all you need. Better yet, get one from the library and copy it. Or try the Internet.


Senior Member
Jan 24, 2002
Professional Status
Certified Residential Appraiser
Starting with the most accessible walls, measure the exterior perimeter of the house, rounding to the nearest ½ foot (reasonable accuracy in my area because of insignificant market reaction to small differences in living area). On legal-sized graph paper, draw each wall as a solid line, to scale. At the same time, indicate, on the same sketch, the position of the second-story exterior walls.

I do this by drawing dashed lines to indicate where the second floor differs from the first. If a second-floor exterior wall ends in the middle of a first-floor wall, take a few steps back from the house and pick a vertically aligned reference point to measure.

Before going into the house, I’ll have completed the first-floor perimeter sketch and most of the second-floor exterior walls (shown as dashed lines on top of the first-floor sketch). When a house has multiple corners and/or angles, I’ll verify my scaled sketch with some reference measurements. These reference measurements can include the total length of one side of the house or the distance of several corners from any convenient reference (a tree, a fence, etc.).

Upon entering the house, measure the garage, again to scale, and show it as a solid line on the sketch.

The next step is to finish the second floor measurements. Still using my first-floor perimeter sketch as a reference, and drawing dashed lines to show where the second floor differs from the first, measure and draw in the stairwell penetration, balcony offsets, etc. In some cases, it is necessary to measure the distances between second floor exterior walls from the inside of the house.

Third floors, basements, etc. are added to the sketch in the same way, using a different line style, e.g. dots or double lines. Keeping everything to scale saves a lot of measuring, because it is common for walls on different levels to line up. More importantly, if your field sketch is done to scale, any mistakes will become immediately obvious. It’s better to swallow your pride and re-measure than to go back to your office and spend an hour scratching your head as you try to figure out where the missing 10 feet goes.

Now that I have all the measurements I need, I’ll do a quick freehand of the second floor’s shape and note the relative positions of the rooms on all floors. I don’t show interior walls unless the floorplan has a functional problem. I always verify the room count with the owner – sometimes a powder room is not obvious, or a bedroom is hidden behind a closet.

I like to complete the sketch using a laptop inside my car, while everything’s fresh in my mind. Using DCSketch, I’ll draw the first-floor perimeter, copy it to the second floor, and then move the walls of the second floor to their correct positions. Deciding which areas to include in the GLA is not always straightforward. In this part of the world, appraisers frequently deal with unpermitted additions, illegal second units, finished garages, and finished attics. My decisions are guided by USPAP reporting requirements, local market reaction to that amenity, and by the instructions of that specific lender.

Depending on the type of house, I choose between three measuring tools: a 35’ steel tape (I use this most frequently and don’t need anything else for most homes), a small measuring wheel (good for large homes with concrete on most sides and also great for the interior measurements), and a 100’ fiberglass tape (I usually pull this out for the ranch-style homes with unpaved yards). The laser devices sound intriguing, but I’m not sold on getting another expensive, complex gadget.

A friend (a commercial appraiser) once talked about doing paperless inspections with a video camera. With the camera recording during the whole inspection (even when hanging on its strap) he would interview the owner, measure the buildings (go 10’, turn right 12’, turn left 50’, etc.) and describe the interior out loud as he toured the building. He would then replay the tape while doing his sketch and description and use frame captures for his pictures.

I too, am looking forward to thin, affordable tablet PC’s because then my notes will become the actual appraisal report.


The first thing I do is ask the owner for a survey or floor plan, most of the time they don't have them but sitting at the kitchen table with a survey and scale sure beats getting cold and wet.

Mike Garrett RAA

Elite Member
Gold Supporting Member
Jan 14, 2002
Professional Status
Certified Residential Appraiser
No wonder I am getting more and more requests for interior walls and doors. Youse guys are spoiling them!

1. Simple exterior measurement of the perimeter of the house. Never seems to match exactly with the public record or MLS...isn't that amazing?

2. Use the sketch program that comes with most good software (stuggling to switch over to Apex from Winsketch). Indicate the rooms with WORDS, ie Kitchen, bath, bedroom, etc. If you want to do more, charge more!
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