Building a Metric Shed

By The Metric Maven

One evening over the phone, my friend Lapin told me that he spent the weekend with another Engineer, Mr. Landi, building a shed. Mr. Landi suggested they build it using metric so it would be more accurate. Apparently this exercise in construction went down hill immediately.  “We made all kinds of mistakes cutting lengths.” Lapin said exasperated. I then asked a question which took Lapin by surprise:

“Did you build it using centimeters or millimeters?”

“It makes a difference?” Lapin inquired with incredulity.

“Yes, you’re prone to make numerous errors when you use centimeters. Millimeters eliminate a major source of those errors, by eliminating the decimal point.”

I explained that in Australia, nothing but millimeters are used for their building construction. The numbers are all simple integers, and no addition or subtraction with decimal points are needed. The least numerate of the workers can use a calculator to add and subtract integers with ease and accuracy. It’s saved Australia about 10-15% on the cost of construction since their metric conversion in the 1970s, when compared with imperial.

It was hard to fault Lapin or Mr. Landi for not using millimeters. In the US, obtaining a decent metric tape measure, or other construction tools in millimeters, is almost impossible, because of The Invisible Metric Embargo.

The formal recommendations for metric construction in the United States is in the Metric Design Guide (PBS-PQ260) September 1995. Here is what it has to say about the use of centimeters in construction:

Centimeters (cm)

Centimeters are typically not used in U.S. specifications. This is consistent with the
recommendations of AIA and the American Society of Testing Materials (ASTM).
Centimeters are not used in major codes.

Use of centimeters leads to extensive usage of decimal points and confusion to new readers. Whole millimeters are being used for specification measurements, unless extreme precision is being indicated. A credit card is about 1 mm thick.

Here is the Guide’s statement about millimeters:

Millimeters (mm)

SI specifications have used mm for almost all measurements, even large ones. Use of mm is consistent with dimensions in major codes, such as the National Building Code (Building Officials and Code Administrators International, Inc.) and the National Electric Code (National Fire Protection Association).

Use of mm leads to integers for all building dimensions and nearly all building product
dimensions, so use of the decimal point is almost completely eliminated. Even if some large dimensions seem to have many digits there still will usually be fewer pencil or CAD strokes than conventional English Dimensioning

A Canadian building construction guide has nice illustrations of the difference—which are absent in the US guide. Unfortunately, Canada’s building trades have not converted to metric, which is why I generally discuss the Australians instead. I have not been able to locate Australian building guides. This is why you will find none in this blog.

The Canadian guide shows how to read a metric tape measure. This tape measure has two units on it meters and millimeters. You can compare it with an Australian tape measure I own below. It remains all millimeters, but only counts off the 100 mm between without the largest digits.

Canadian Illustration of How To Read A Metric Tape Measure (click to enlarge)
Australian Metric Tape Measure (click to enlarge)

Next the Canadian guide shows a typical wall dimensioned with imperial units.

Example Wall With Imperial Dimensions (click to enlarge)

It never strikes Americans as excessive to use two units to describe every dimension. Feet and inches are found everywhere, along with fractions.

The same wall is then presented as it would be dimensioned and drawn using millimeters. The numbers are all simple integers.

Example Wall With Metric Dimensions (click to enlarge)

No Feet and inches, no fractions, no decimal points, and just one unit used for all sizes. The dimensions are easy for a novice or experienced builder to read clearly. Experience in Australia shows that workers will attempt to cut to the exact millimeter when given tools with that capability. We would have more accurately constructed buildings, which are more weather-tight, simply by switching to metric.

Pat Naughtin relates that the head of AVJennings construction in Australia had two identical houses constructed, one in imperial and one in metric. It took two large trucks to haul away the scrap from the imperial work site. The metric house work site had only about a wheelbarrow full. When reformed in a rational up-to-date manner, metric can provide easy dimension checks.  Pat relates that Australian bricks are 90 mm thick, and are specified to have 10 mm of “mud” between them. This means that if you have ten rows of bricks laid down, they should measure exactly one meter. Imperial units simply do not accommodate this manner of easy check.

One owner of an Australian construction company has a blog entry with a title which is succinct concerning our American building practices: Why not going Metric makes America a laughing stock. He concludes his blog entry thus:

One of the last hold outs in a the push toward metric is the American building industry. The lure of inches for lumber and lengths in feet is seemingly irresistible. (it is even curious that the Americans call that timber a 2X4, where in Australia it was a 4X2) To avoid the confusion…… the Australian building industry declared.

The metric units for linear measurement in building and construction will be the metre (m) and the millimetre (mm), ….. This will apply to all sectors of the industry, and the centimetre (cm) shall not be used.’

We banished the centimetre as some defacto inch measurement and have never looked back.

It speaks volumes about the US that they believe in some unalienable right to an outdated, and uniquely strange system of measures in this current millennium.

Related essay:

The Metric Dream House


If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.


The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.


The third book is not of direct importance to metric education. It is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.

The “Preferred” Measurement System of the US

By The Metric Maven

Bulldog Edition

The object to the left is an everyday thing, but it is making a clear statement about the designer’s measurement preference. It may not be apparent what the measurement preference is to you. It might not have been to me had I not read The Design of Everyday Things by Donald A Norman (suggested to me by Sven). The design of even the simplest of objects is done in a manner that provides information on how the designer intends them to be used. A person will unconsciously take an intended design clue, and use an object as intended. Knives are provided with handles, and one doesn’t stop to think which is the best end to hold in one’s hand after early experience and instruction in childhood. Norman cites research which argues there are at least 30,000 everyday things around us, and decreases the number to 20,000 to state: “Suppose each everyday thing takes only one minute to learn; learning 20,000 of them occupies 20,000 minutes —333 hours  about 8 forty hour work weeks.” We have a considerable amount of time invested in learning about our everyday things. When we encounter a can opener, or a scissors, or a potato peeler, we generally know exactly what to expect, how to hold it, and how to use it. One way that a designed object signals how it should be used, is to design it so the ways it may be used are limited, this is called affordance by Norman.

When I worked on the design of televisions, I immediately ran into the idea of affordance. A television motherboard and its chassis were dropped off in my lab, but about seven cables had been disconnected. I protested that it was all apart, and was calmly told by a technician  that all the plugs would only go into one place on the motherboard. Indeed, they did, and I was impressed that because of this affordance, I couldn’t make a mistake.

The affordance of the TV motherboard was essentially foolproof, but often designers can’t restrict a user that much, and the affordance involves only discomfort or a subtle tactile clue. Donald Norman offers this:

Take another example of good design. My felt-tipped marking pen has ribs along only one of its sides; otherwise all sides look identical. Careful examination shows that the tip of the marker is angled and makes the best line if the marker is held with the ribbed side up, a natural result if the forefinger rests upon the ribs. No harm results if I hold the marker another way, but the marker writes less well. The ribs are subtle design cue—functional, yet visibly and aesthetically unobtrusive.

Norman also shows numerous door handles as examples. If we see only a push plate on a door, we have no other choice but to push to open the door. A handle which one can readily grasp cues us that we pull to open it. This brings us back to the measuring cup shown above. Its design is pro-metric, as the metric graduations are facing a person’s eyes when it is held with the right hand. About 70-90% of the worlds population are right handed. Right handed Americans using this measuring cup, would find it uncomfortable and unnatural to place the handle on the left. The measuring cup shown is from the period when the US pretended it might go metric. Measuring cups of this same type, which are currently sold in the US, are all designed so that the imperial graduations face one’s eyes when held with the handle on the right. One of mine is shown below:

Common American Measuring Cup

Measuring cup designs have improved since the 1970s. Some of the ones I now own are “top readable” and only sold (unfortunately) at product parties. Dual scale is always a hindrance to metric adoption, but this set of top reading measuring cups are the best I have encountered.  I have visited many cooking stores and looked online, but have yet to find metric-only measuring cups and measuring spoons. The measuring cup shown below appears to have eliminated a right hand bias as well as being easy to read. Now if I could just purchase a metric-only one.

Top Read Measuring Vessel with Clear Metric Graduations
Left Handed Ruler

The design of common measuring cups is but one example of subtle anti-metric bias in our everyday things. In a previous blog I mentioned that the design of American “metric” rulers hinders their use because of the presence of a centimeter-millimeter dual unit scale, and the rounding of the origin end of one particular metric scale. The origin of the inch scale is placed on the square end, which is much more natural for measuring. For about 10% of our population, which are left-handed, the current dual scale measuring cups are adequately designed for metric use. On the other hand both metric and inch ruler scales  have equally low affordance for left-handed people. Left hand rulers exist which have the numbering from right to left to increase the ease of use by a left handed person.

My father gave me an expandable wrench for my last birthday, which has mm markings on one side, and had inch on the other (yes, I ground off the inch scale). If one holds the wrench as a right handed person would, the inch scale faces your eyes. On the opposite side is the metric scale, which has low affordance for a right-handed person. The wrench is nice because it allows one to immediately see what size a bolt head is in mm, but it is very cumbersome for me to use, as I’m right handed.. I have a better understanding of what left handed people deal with on an everyday basis in our world.

Expandible wrench designed with an affordability preference for inches (click to enlarge)

These examples point to the fact that a preference for imperial measures is designed into our US tools, and US everyday things. But I’ve been assured by non-binding legislation that the US prefers metric measurements. Here is some background:

The Omnibus Trade and Competitiveness Act of 1988 was signed into law by Ronald Reagan. It amended the Metric Conversion Act of 1975, yet didn’t have the word metric in the title of the legislation. President Reagan and Congress apparently were concerned that the voluntary nature of the Metric Conversion Act of 1975 was not clear enough.

Section 3 of the Metric Conversion Act of 1975 is amended to read as follows:

SEC. 3. It is therefore the declared policy of the United States

(1) to designate the metric system of measurement as the preferred system of weights and measures for United States trade and commerce;

(2) to require that each Federal agency, by a date certain and to the extent economically feasible by the end of the fiscal year 1992, use the metric system of measurement in its procurement, grants, and other business-related activities, Except to the extent that such use is impractical or is likely to cause significant inefficiencies or loss of markets to United States firms, such as when foreign competitors are producing competing products in non-metric units;

Well, it has been the case since the 19th Century, that switching to metric is always “impractical” in the US. Apparently there was much concern among our legislators that we have an exception: “such as when foreign competitors are producing competing products in non-metric units;” Apparently Liberia and Myanmar (the last two non-metric holdouts in the world) might flood the US (and the world?) with non-metric products, and thereby destroy what’s left of our uncompetitive non-metric US economy. Thank you President Reagan and Congress for the foresight to see the threat and protect us from the economic danger posed by these two tiny countries, and making an exception. Clearly the 1992 date was meaningless and arbitrary. It made it look like the government was taking action, when in fact it was not. Metric is 21 years past the expiration date for becoming “preferred.”

One can easily see how “preferred” metric is in the US simply by inspecting the design of our everyday things and everyday tools. The legislation is feckless, and crass hypocrisy. It is in line with the strange belief that if we cling onto the trappings of our past, the future may be indefinitely postponed. This emotional response, written in legislation, only postpones the day when reality intervenes, and forces Americans to realize that fantasy is no match for reality. I’m not willing to wait another 150 years hoping America will come to its senses. We need legislation that compels industry to design and make available true metric products, during a short compulsory switchover by industry, government, and education to metric. What we have now is legislation celebrating the the metric system as the preferred system of the future and makes sure it will always remain so.

Related Essay:

The Invisible Metric Embargo


If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.


The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.


The third book is not of direct importance to metric education. It is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.