Architectural Drawings: Gospel or Intent?
October 2009Every bid, every job, comes with its own set of plans: drawings, details, spec books. Sometimes the plans come complete, sometimes not. In fact, by survey it seems that the national average pegs completeness at about 80 percent these days.
But complete or not, the plans always include a set of architectural drawings. The burning question is: Can you trust them?
Maybe, is the short answer. For the long answer, read on.
Disclaimer: Do Not Scale Drawing
Hardly any drawings today, especially those delivered electronically, fail to include some version of this disclaimer.
Examples are these:
"Do not scale drawing, work to figured dimensions.”
"All dimensions to be checked; do not scale drawing.”
"Use dimensions shown, do not scale drawing.”
And to top it off, this ominous paragraph: "Do not scale dimensions off drawings. Use written or calculated dimensions. The contractor is responsible for checking dimensions before ordering or starting work.”
"About 50 percent of the drawings we see also say, ‘Not to be used for construction,’” adds Gerald Roach of Forks Lath & Plaster in North Dakota. "Or even, ‘drawings are only complementary,’ or some such language.”
But what exactly does the architect mean by the ubiquitous "Do Not Scale Drawing” disclaimer? Opinions vary.
Estimators. Dave DeHorn, chief estimator at Brady Company in California, feels that "the architects are definitely shoving the liability downhill. And we’re a long way down that hill.”
"What they mean,” says Jason Price, estimator at Sides Drywall in Alabama, "is that the written dimension always overrides the measurements of the graphics. The architect may have pulled the graphic from a shop drawing, and not bothered to scale it correctly. So they’re telling you that any written number dimension overrides what that wall may actually scale on the plans.”
Glenn Sieber, chief estimator at Easley & Rivers, Inc. in Pennsylvania, agrees that the disclaimer says "not to measure the graphics, but to only go by the written numbers.”
Gabriel Castillo of Pillar Construction in Virginia also shared his interpretation: "It means that nowadays, as we’re sharing the documents electronically, we don’t know what type of printer or display device will be used, so the architect wants to make sure that it’s not his fault if you print it scaled to whatever format you want, because it may not come out right. He’s saying he’s not responsible for the accuracy of the scale if you print the file.”
Roach adds, "It means, don’t go by their graphics measurements, go by their numbers.”
Architects Weigh In. Walter Scarborough, AIA, CSI, CCS, vice president and manager of the Dallas regional office of Hall Architects, explains, "The issue is that drawings when they were hand-drawn, were hard to accurately make to scale since you’re dealing with a small representation of a big thing. That’s why we spend a lot of time calculating and indicating dimensions, for the danger is that if an installer actually scales the drawing, he or she may end up with a different dimension than what’s shown on the dimension line.
"Also, sometimes things change, and rather than change the graphics and move it over the equivalent of 3 inches, we only change the detail number.
"The accuracy is in the notes, in the numbers, not in the graphics. When you draw a floor plan, for example, at an eighth of an inch to 1 foot, just the width of the line on the paper represents 6 real inches. Therefore, the issue is that measuring drawings isn’t accurate enough.
"If the dimension is not written, and is not apparent, the proper thing to do is to ask the architect. It is the architect’s obligation to give the contractor accurate information.”
Levi Patterson, architect with DLR Group in Portland, Ore., confirms Castillos’ take: "What it means to me is that they don’t want you to shrink or enlarge the actual drawing that they sent you, especially if it is a PDF file. It’s easy to shrink to fit, or fit to page size, so that it prints the size of the paper rather than to scale. The problem with PDF files is that they are not dimensionally stable.
"So they don’t want you to put a ruler to the drawing and hope to get the exact dimensions off the graphics. You should take the dimension from the written numbers.”
Philip G. Pipal, architect and senior project manager at Carrier Johnson in Costa Mesa, Calif., sheds this light on the disclaimer: "Drawings have always carried this disclaimer; it’s not only the electronic ones. Even when we were doing them by hand, it’s always been a CYA disclaimer that architects put on their drawings because when drawn by hand you tended to take more shortcuts.
"You would find people not drawing things to scale when they did them by hand. We’ve always told contractors not to scale drawings.
"In other words, don’t measure the drawing and assume that a quarter-inch on the drawing really means one foot in real life. That disclaimer was always there. Today, it’s a standard CYA on electronic drawings.”
A Legal View. William A. Lichtig, a California attorney specializing in construction contracts, comments, "The do not scale drawings” language is a vestige of the old technology. Everything from "shrink to fit page” to photo copying machines can wreak havoc with the ability to accurately scale drawings. Hence, the disclaimer.”
What It Means. At the end of the day, "do not scale drawing” tells the contractor not to take the drawing as gospel. The dimensions of the graphics may or may not be correct, so if you were to construct a project based on those measurements, you may have an ill-fitting mess on your hands.
The disclaimer says to go only by the written numbers in the plan details or spec books.
The Estimator’s Problem
On paper—pun intended—this seems clear-cut enough: You should only use the written numbers. However, from an estimating standpoint, using only written numbers is easier said than done; in fact, it’s never done. Every estimating software on the market today uses the drawing graphics to calculate dimensions and quantities.
DeHorn: "They tell us not to scale the drawings, but as I do my takeoff electronically, I have to.”
Price: "Our estimating software draws an overlay image on top of the walls we’re taking off, and it highlights these without changing the scale on the drawings.”
Matt Van Hekken, chief estimator at The Bouma Corporation in Michigan, concurs. "For on-screen takeoff,” he says, "we go by the dimensions of the drawing, the graphics.”
Sieber: "We scale the drawings all the time. It’s the only way that we can effectively do our takeoffs. Were we to only use the numbers, it would take forever.”
Castillo: "Nobody takes off by the written numbers, it would take too long to be profitable.”
There is really no way around it, the estimator has to use the graphics of the drawing to take off the job in a timely and cost-effective manner. What you must do, however—and all estimators interviewed do—is to ascertain, as well as you can, that the scale you are working with is correct.
DeHorn: "If my electronic file says one-eighth of an inch equals one foot, I will then spot-check a few of the measurements on each page to make sure that my scale comes out to what the floor plan says it is. If it does not, I have the ability to adjust the scale in my software.
"We always check the scale, whether we receive the plans electronically or as prints from the blueprint shop.”
Price agrees: "With the estimating software we use, we do it all on screen. And it has a tool that allows you to check the scale, or to set the scale to the dimensions on the plans. I’d say that 90 percent of the time, the scale is correct. The other 10 percent of the time, we adjust the scale according to verified portions.
"We find a dimensioned line somewhere on the plan, and then click the two end points and type in what that dimension is supposed to be based on the detail. And if the scale is off, the software will adjust the scale of the overlay image to match the detail.”
Sieber: "Now, the first thing we do is—and this is a hard and fast rule: We check the scale dimensions, both east to west and north to south. And we periodically spot-check the drawings as we go along to make sure that everything is to scale.
"We have to rely on the dimensions on the drawings, and usually the scaled dimensions are in accordance with the given dimensions. If they are not, we have the ability on the digitizers to make adjustments for that.”
Castillo concurs, "We verify the scale on every page of the drawings. Mistakes can be very costly.”
Architect Pipal is aware of the problem, and that estimators always use the graphics for takeoff, but adds, "When they do, I think that they are taking a certain amount of risk. That said, I also think that drawing systems have progressed and things tend to be more accurate these days.”
Sieber adds, "The estimator’s job is to spot anything that’s out, and if he does, he’s has to make some extrapolations. If he notices incorrect measurements, he has to be able to work out what they should be. We know that the estimator has to make corrections in those instances.
"Of course, that does not relieve the architect from having to draw that section correctly. But we also know that this is the way things are sometimes, and that there are things that the estimator will have to extrapolate.”
Although ubiquitous, "Do Not Scale Drawing” is not the only type of disclaimer we see today.
Price says, "We often see the caution that we should look at drawings for all the trades, say plumbing, electrical, mechanical and structural—in other words, the whole set. They are concerned that we may only print the structural and not the other parts of the plan and so miss something that showed up on another set of plans for another trade. We see that disclaimer a lot.
"As a rule, we in the drywall trade only need the architectural and structural drawings, but they say that if you don’t study the electrical, mechanical and plumbing drawings, then they are not responsible for anything that you might have missed.”
Van Hekken says, "We see the disclaimer that if there’s a conflict between the drawing and the architect’s intent, we should go with the intent. The problem is that we’re not bidding intent, so there is a fine line to walk between what you feel may be their intent and what’s on the drawing. Can we afford to bid what we believe they mean, and still be competitive?”
Sieber adds: "We often see stamps on drawings that it’s at 50 percent or 60 percent, and that’s a heads-up that the scale is off.”
Several other estimators concurred on this point; they often see mentions that the drawings are at "half scale” or 60 percent, which of course means that they need to make the necessary adjustments before taking off the job.
Digital files are not impervious to distortion and error.
The following interesting disclaimer was found online: "Computer Aided Design (CAD) data are being provided to the recipient of this disclaimer. We make no representation as to its completeness, currency or accuracy because of reasons inherent to CAD. All digital CAD data appear to be extremely accurate, however, this apparent accuracy is an artifact of the techniques used to generate it, and is in no way intended to imply actual accuracy. The user of this data takes full responsibility for the accuracy and correctness of all measurements, area, inventories or other data extracted from this, either manually or with the use of a computer.”
Files that are compressed—zipped, for example—before transmittal, and decompressed upon receipt are supposed to retain 100 percent integrity, and for the most part, they do. However, we came across instances both with estimators and architects where things were lost or distorted as a result of digital processing. Nothing major, but some of the detail was lost, and this—and other digital distortion—is apparently common enough to prompt the above disclaimer.
Competing Software. An uncompressed AutoDesk file sent from one person to another is virtually guaranteed to retain 100 percent accuracy. A compressed file from same to same software is most likely also to be error-free.
However, an AutoDesk file converted to, say, TurboCAD, stands less of a chance to be free of error.
Commercially, it is not really in a software vendor’s interest to be 100 percent compatible with its competitors; for while all vendors have token converters for most of their competitors’ files—which work fine most of the time—they all want to rule the roost and would rather that no one used "the other” brand of software, and certainly do not want to encourage such use by providing perfect converters for them.
Vigilance. Digital distortions of one form or another will occasionally occur. Your only solution is to stay vigilant when dealing with possible distortion, and always verify the scale, once, twice, three times per page.
"The first thing we do,” suggests William Shakespeare in Henry VI, "let’s kill all the lawyers.”
An extreme remedy, perhaps, but the Bard of Avon was nothing if not observant, and he certainly saw the problem in his day—a problem that has not eased over the years.
Legal disclaimers are a way to shift responsibility—in this case from architect to contractor, and they are a fact of life. It is important, however, to know exactly what they mean in real terms, and how to work with them.
Attorney William A. Lichtig makes the observation that, "As we move forward into BIM (Building Information Modeling) technology, the ability to "scale” within the model will become commonplace.
"The technology is designed to afford the viewer the ability to click and drag between spots and have the model generate the dimension. While this will work wonders when working in the model, there is still likely to be an admonition about "Do Not Scale” when there is a transfer between formats, i.e., the model to paper. Since the producer of the model cannot assure that the format of the printing will not ruin the scale, it would be foolish to eliminate the warning.”
Gospel or Intent?
The graphics part of any drawing is not gospel. If anything, it represents the architect’s intent and in most respects should be viewed that way.
The everyday reality that estimators and their software must rely on the graphic representations of the project drawings means only one thing: Stay vigilant, and verify scales and measurements as often as needed to be certain you have it right.
Coeur d’Alene, Idaho-based Ulf Wolf writes for the construction industry as Words & Images.