Shop Drawing Review

[SteelPE]

When doing shop drawing review, specifically steel shop drawings, do you guys check dimensions or leave that for the architect to verify? Or do you even expect the architect to look at the drawings? I have had some architect say that checking the structural shop drawings is my responsibility. When it comes to dimensions of I am finding that I may note the architect to verify dimensions (say around a stair or a slab opening) only to have the shop drawings come back a month later with the same questions in regards to dimensions I asked the architect to verify.

 

[Hokie93]

IBC 2012 (and earlier versions) section 1603.1 requires that "Construction documents shall show the size, section, and relative locations of structural members with floor levels, column centers, and offsets dimensioned" (emphasis added). So unless the architectural drawings show every structural member and dimension them, I don't see how a set of structural drawings with NO dimensions satisfies IBC. Even if it did satisfy IBC, it is not how I document a design. I am not leaving the dimensioning of major structural members up to an architect who is, most likely, clueless about the concept of proper dimensioning.

 

[TXStructural]

glass99: "Structural engineers always exclude layout dimensions from their scope. Its kind of basic!"

I can't imagine sealing a drawing that did not include such a basic thing as plan dimensions. In fact, in my world, that might be considered negligence, since such dimensions determine flexural capacity of beams and load on columns. We always dimension things like how far the edge of slab is from a supporting member, elevations of slabs, and, usually, slab openings. Are these "layout dimensions", or am I missing something?

In fact, I have a presentation I have done across the country discussing the need for engineers to coordinate and provide dimensions, because it is critical to an efficient construction process and to assure the design intent is provided in the CDs.

As far as checking shops goes, the current practice of not actually checking them, and passing the responsibility to others, goes back to the collapse of the walkway at the Hyatt in KC. The series of unfortunate events included a failure by the engineering team to identify two critical but seemingly minor changes, between the engineering drawings and the shops, that were the physical cause of the collapse. The change was made for constructability reasons and the contractor did not realize the change interrupted the load path. A rushed shop drawing check by a junior engineer who was not familiar with the design of that element missed the change. Since that time, the industry has chosen to avoid liability by doing less to avoid a mistake. There are engineering firms that take this very seriously. They detail carefully, check shops thoroughly, and they inspect during construction. Unfortunately, owners seldom want to pay for that level of engineering service.

 

[glass99]

TXStructural: I agree that structural engineers should have dimensions on their drawings. The point is that the conveyed by the dimensions is that the structural member will work at that span, or that the slab opening at that scale is acceptable. It does not mean that it is the last word on the dimensional layout because that is the architect's job. It can't be the structural engineer's job because its coordination between the various other movable pieces like finishes and mechanical are done by the architect.

Also agreed that checking shops is underrated.

 

[spats]

As the structural engineer-of-record, I feel it is my responsibility to coordinate my drawings with the architectural drawings, including providing all necessary structural dimensions. When I check shop drawings, I check the overall grid-to-grid dimensions, beam spacing, etc.. This is my last chance to catch any errors on my own drawings. I also spot check the detailed component dimensions enough to establish a level of comfort that the detailer knows what he's doing. The more errors I find, the more I check. If it gets too bad, I ask that they "revise and resubmit". This is especially true if it's obvious that the drawings were not peer checked by the steel detailer prior to submittal. I know it is not my responsibility to do this, but I've learned from experience that a little checking can potentially avoid a lot of headaches later on. I know we've all been put in the position of having to come up with a field fix for an error that we somehow never get paid for doing. Nobody wants to be put in the position of having to ask the client for more money to fix stuff that was never properly checked. Finger pointing is something to be avoided.

Your structural stuff will get built first, long before any architectural-only stuff, so it must be right. What structural shows is what gets built. I've also seen in a lot of instances that the GC does not even send the architectural drawings to the steel shop, let alone the written specifications.

 

[CELinOttawa]

Interesting to note:

- In Canada: Like Kootk, I have found that Canadian firms frequently do not dimension but instead refer to a specific dated release of the Architectural drawings. I hate this, disagree with this passionately, and refuse to do this in our own practice.

- In New Zealand: The Architectural drawings frequently do not show dimensions and overall layouts. These are found on the Structural drawings. The Arch shows egress lengths, specific little detail dimensions, etc. Nothing affecting spans and overall room dimensions. This has the huge advantage of the person who's work is affected by wall positions, lintel lengths, etc, being in command of these dimensions.

 

[hokie66]

What is interesting to me is that the practice varies so much from country to country. Australia is like Canada, apparently, with none or very few dimensions on the structural drawings.

 

[CELinOttawa]

Second significant difference between NZ & AUS I've heard in one day... Being such close cousins, that surprises me more than practice differences between CAN & US.

 

[jayrod12]

I work entirely in Canada and dimension everything required to erect the building on my drawings. I feel the contractor should be able to provide a structurally sound building shell from only the structural drawings.

 

[hokie66]

I thought that way also, when I worked in the US. But the system here seems to work just as well...or just as poorly in some cases.

 

[CELinOttawa]

jayrod: Do you reference a specific Architectural set with the date? Otherwise I think you're going to eventually miss something and wear it... Architect change their minds more often than clients. If they change the dims after everything you've done has gone out, and (as usual) fail to inform you, this could be disastrous.

 

[hokie66]

CEL,
I think that is why the Aussie system developed the way it has. I still have memories, in the US, of late nights spent checking and changing dimensions due to last minute architectural revisions just before the last addendum. And with Australian architects tending more toward sculpture than practicality, I wonder often how the detailers work it all out so well.

 

[CELinOttawa]

I suspect the reality is late and last minute changes happen less for any system where the engineer does not show dimensions. No way of knowing, but it is what my gut tells me after working in both...

Likely goes like this: Detailers work for the Contractor, who just says it will cost more. More often than not detailers, shop workers, and the contractor's plethora of staff in general have more power to say "No" to a change than we do...

 

[jayrod12]

CEL, yes. I reference the architectural drawings that were used for the creation of the drawings in one of the first notes on the first page. That also includes the same note that the contractor must report all discrepancies between drawings to the engineer immediately.

 

[jayrod12]

If I were a contractor I would hate having to flip back and forth between the structural and architectural drawings during the framing process. That seems ridiculous to me. Especially if it is only for dimensions, what a waste of his time.

 

[glass99]

jayrod12: Yes its ridiculous but its all about liability. We live in a world where our firm's profit on a project is multiple orders of magnitude less than the construction cost.

 

[jayrod12]

I understand liability. I have the countless professional development hours at boring seminars to prove it.

I think it is lazy if you cannot provide dimensions and some CYA statements saying which architectural drawings it is based off of and that the contractor and architect are responsible for confirming the dimensional accuracy.

When I go to peer review another engineer's work I don't want to be flipping back and forth between drawing sets either. I should be able to redesign the building from the structural drawings alone and should not have to go hunting for a dimension I need for design. If during the course of your design of the building you needed to hunt for a dimension then you should be including that dimension on your drawing. Passing the buck onto the contractor to successfully figure out is a cop out and is just asking for mistakes.

From my own experience more mistakes happen when the contractor is expected to hunt down a dimension.

 

[CELinOttawa]

Your practice, your choice. In my opinion the duplication of any information is a mistake and a predictable source of error.

 

[jayrod12]

Both arguments are valid. I agree that by not duplicating the information you remove that predictable source of error. The key word there is predictable, when you don't show the dimensions you open up the possibilities to unpredictable errors in translation between drawings.

 

[glass99]

jayrod: yes hunting for dimensions causes mistakes, as do conflicting dimensions. You would have to agree a too many cooks in the kitchen problem does exist.

Layout dimensions are the bane of my existence. If you are building a rectangular ground up big box store with column lines exactly 30ft O.C. both north and south I assume its easy, but if you are doing a retail renovation in an 1920's NYC building, noone, not even the architect has complete control of the layout. You are working from a hodge podge of site measurements and smudged low-res scan of original drawings, plus you have an owner and architect who are designing as they build.

 

[jayrod12]

I guess it also does depend on the project. I took a peek at the structural drawings for a new arena they built here in town that our firm did. There are next to no dimensions on it at all. There's also a few hundred drawings for structural alone, I can see how dimensioning that on more than one set of plans could be mistake prone.