How do you measure up?

Experts share ways to get the right measurement the first time

Have you ever hastily taken a measurement, raced to the saw and made the cut? Then, with trimmed piece in hand, eagerly laid it in place to find that it’s the wrong size?

Experts in measurement ’fess up to these problems, so don’t feel as if you’re the only one who has made misfired measurements. But because these experts work with end-users every day, listen to their frustrations and watch their work, they also have good ideas on how to make precise measurements.

Whether you’re using a tried-and-true tape measure, a square or the latest generation of ultrasonic or laser measuring tools, if you don’t pay attention to the basics, you’ll come up short – or long.

Common measurement mistakes
“The most common problem is using the wrong measuring tool for the job at hand,” says Philip Hanson, market development officer at The C. H. Hanson Co. “A framer needs a different level of precision than a finish carpenter or a tile layer. Selecting the right tool for the job makes a difference.”

Kyle Dancho, director of Stanley measuring and layout products, and John Murray, director of engineering measurement, find a tool as simple as a tape measure gets misused.

Dancho reports that Stanley representatives often get tape measures  from customers who have hammered the rivets tightly to the tape.

“The play in the hook is there for accuracy. It accommodates for the thickness of the hook while making inside dimensional measurements, yet be accurate when the tape is hooked to an edge,” says Murray.

Improper measurements often come with fast readings. “Get to know the markings on your tape measure. Adding fractions wasn’t much fun in school, and trying to do it in your head will lead to mistakes. Write measurements down and think through them. Inexpensive construction calculators can also help,” says Dancho.

When making cut marks on material, Murray suggests using a “V” mark to pinpoint where to cut. “It shows the exact point to cut. Then, always make the cut on the waste side,” he says.

For rough window or door openings, Dancho suggests taking measurements at the top, the middle and the bottom to make sure your cut accommodates variances.

When markings wear off a tape measure, the experts recommend getting rid of it.

Getting square
The 3-4-5 method of establishing a right angle is a time-tested method, but that doesn’t mean seasoned workers can’t screw it up. “Using two people and two tape measures to lay out a right angle can lead to inaccuracies. If one person measures on the inside of the mark and the other measures the outside of the mark, the 90-degree angle will be off by the width of the tape measure in 3',” says Hanson.

“That’s why the aSquare has been so popular. The lightweight, yet durable unit unfolds and snaps into place to create a 3'-4'-5' square that eliminates measuring. It is accurate to within 1/32" in 4',” he says.

Measuring long distances
“A common example of using the wrong tool for the job is when a contractor begins to lay out an area using a 16' tape measure. During jobsite layout, the tape must be positioned three or four times to get the desired distance. With every pick up of the tape, there is a chance for error,” says Dancho.

“If the same contractor used a 50' or 100' tape for the job, there is a much greater chance of getting an accurate measurement.”

Long tapes require some attention to assure accurate measurement. “If extreme accuracy over distance is important, use a metal tape. Fiberglass tapes are fine for rough layout, but can stretch and throw measurements off,” says Dancho.

Although fiberglass tapes are more resilient to moisture and dirt, they should be wiped off if they are exposed to dew, rain or dirt. Metal tapes should be dried and a fine layer of oil applied with a rag before winding the tape.

High-tech measurement
Electronic measuring systems can be low cost and great for estimating and, at the higher end of the range, they can offer very good accuracy across distances.

“The two main technologies rely on laser or ultrasonic measuring. Ultrasonic is less precise but good for estimating for flooring, painting or HVAC sizing. At 50', it is accurate to ±3". With one-person operation, it’s convenient to use,” says Murray. Cost: between $30 and $50.

Laser measuring devices are much more accurate, achieving ±1/8" or ±1/16" over 50'. “These are also operated by one person and cost between $300 and $600,” Murray says.

In either instance, the tool must hit something to bounce a signal back to the tool. If there are obstacles in the way, you may get an incorrect reading. Many of the ultrasonic tools incorporate a pointer laser that helps identify the bounce-back point. “They can be tricky to use, but if you understand the concept of how they work, they can be very good tools for one-person measuring,” says Dancho.

Measurement by mark
“Measurements are a problem even for pros,” says Phil Brumley, inventor and marketer of the Trim-Gauge. “Often, two things go wrong. You make a measurement and you forget it before you get to the saw, or you transpose the measurement or misread the tape and make the wrong cut. In 25 years of carpentry, I remember the old timers, some of whom were immigrant craftsmen saying, ‘Mark it and cut it. Forget about measuring.’ That’s why jig blocks and tools like the Trim Gauge can help with accuracy.

“The Trim Gauge works like a portable jig block. You establish your reveal, then line up the slide and transfer that mark to the workpiece. “You aren’t measuring, you are aligning to make a cut. It takes the numbers out of it,” he says.

Published in the March 2005 issue of Contractor Tools and Supplies magazine.

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