Why have shop drawing review? 1

[RDK]

Here is a question that follows from Flbob’s question regarding shop-drawing approvals.

Why do we really have shop drawings submitted in the first place?

This is not a naive question. I have been in the construction field for 26 years. I know that shop drawings are required for the fabrication shop to be able to concentrate on their work without all the design details of other work and to allow them to control the production in the most cost advantageous way for them, but why review the drawings and then take no responsibility for the drawings.

We insist that the contractor submit shop drawings before beginning fabrication, hold up the start of fabrication until they are reviewed and returned, then if there is a problem we attempt to put the onus on the contractor.

This does not seem fair to me. If we are going to hold the work up so that we can review the drawings then we should assume some of the risk. If the risk is only the contractors than why hold him up in the first place.

I have a problem with the ethics of getting paid for reviewing the drawings and then not taking responsibility for the results of the review.

Here is my proposal. We make submittal of shop drawings optional for the contractor. Submittal of drawings is only a way to help the contractor check for any errors before the work starts. If the contractor produces a final product that is outside of the contract then the responsibility would clearly be his and his alone.






Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion

http://www.kitsonengineering.com

 

[kayah]

I agree with you to a certain extent, but when you review shop drawings, what are you actually reviewing? Our approach is that shop drawing review is only to determine conformance with the general design concept - that the drawings have been interpreted correctly and reflect the intention of the design. We do not check the detailed design of, for example, the connections - and should not be expected to assume any responsibility for doing so.

Consequently it is important that everyone involved in the process understands exactly what the "review" covers, and what it does not - avoiding ambiguity and later problems. If we are being paid to perform an overall review then we should (and no doubt do) assume responsibility for the results.

Timely shop drawing review is surely in everyone's interest - the contractor avoids potential costly mistakes, and the owner & engineer ensure that they get what was intended. Unfortunately any delays in this process will offset the potential benefits. It would be interesting to see how many contractors voluntarily submitted shop drawings if not required to do so.

 

[dik]

We often get shop drawings without a signed review from the contractor and they scream to the owner about delays when they are returned without review...

Under remarks:

Remarks: Consultant’s Review of Shop Drawings is Void unless the Contractor has reviewed drawings as noted below.

On the shop drawing review, I make reference to the above note that is carried on the transmittal. Also, in the footer of the transmittal, I have the following note:

The documents referenced above have only been reviewed by the Consultant for general conformance with the design concept of the Project and general compliance with the information given in the Contract Documents. All Work is subject to the requirements of the Drawings and Specifications. Review of a specific item does not constitute approval of an assembly of which the item is a component.

The Contractor shall review the above drawings and his responsiblities include:

dimensions which shall be confirmed and correlated with job site conditions,

information that pertains solely to fabrication processes,
means, methods, techniques, sequences and procedures of construction,

safety precautions and programs in connection with the Work,
coordination of his Work with that of all other trades, and

satisfactory performance of the Work.

This was modified slightly about 6 months ago as a result of information 'gleaned' from one of the engineering newsgroups.

 

[GeoPaveTraffic]

I have one word on why shop drawings must be reviewed, Hyatt.

The collapse of the Hyatt Hotel walkway in Kansas City, Missouri over 10 years ago should be all the reminder that any of us ever need as to why shop drawings must be reviewed by the original designer. For those of you unfamiliar with the failure, a walkway collapsed during a new years eve party and many people were killed. The reason the walkway collapsed was a connection was changed in a shop drawing and it was not caught, the resulting change doubled the load in a double channel, which then failed causing the collapse.

I will try to find and post a link to the story for those that are interested.

 

[Rubbrdux]

Here is the URL of a very clear discussion of the incident to which GeoPaveTraffic refers

http://www.uoguelph.ca/~ajenney/webpage.htm

 

[IRstuff]

My background is Aerospace, so it's not clear how shop drawing review fits into the process that I'm more familiar with:
Preliminary Design Review (PDR)
Critical DR (CDR)
Design Verification Test (DVT)

Seems to me that drawing review falls somewhere between DR and DVT. For military customers, CDR and DVT are mandatory steps to validate the detailed design and then to prove that the design meets requirements. Since that's obviously difficult to do with a building, seems to me that a drawing review is a mandatory thing that all parties should participate in and the implementation has to be adequately defended from all challenges.

If such a review is not performed, how does the customer get assurance that the design and implementation meet the customer's requirements? Do most customers simply take the word of the contractor that the analysis and review have been adequately performed?

TTFN

 

[GeoPaveTraffic]

Rubbrdux, thanks for finding the link.

 

[RDK]

IRStuff

Shop drawings are drawings prepared by the contractor for the fabrication shops to produce the actual building components. For example a set of contract drawings will show, in addition to a lot of other information, the size shape and amount of reinforcing to be used in the concrete. The only information useful to the rebar shop, which has to cut bars to length and bend them to shape, is the information on the steel. They will review the contract drawings and prepare a separate drawing with a schedule that shows in greater detail the shape, bend radius (from the applicable code not usually from the drawing) number of each shape and assign each shape a tag number that will be used in the field to sort the steel etc.

Another example would be in cutting large steel plate sections to fabricate some bins. The shop drawings would show which pieces were to be cut from stock sizes to minimize wastage and numbers of cuts. It’s a simple layout process.

These shop drawings are then all that is sent to the fabrication shop to cut and bend the steel. There is not generally a lot of design and analysis put into the shop drawings. Sometimes detailed connection design is put into the contractor’s hands and these have some significant amount of design involvement

I am not sure that there is an exact parallel outside of building construction.

I am not claiming that shop-drawing reviews serve no useful purpose. It does serve as a check on what is being ordered and fabricated.

Why not make them voluntary for the contractor and put the onus for constructing the works in accordance with the drawings and specifications on the contractor? Having a mandatory review prior to starting fabrication obfuscates the responsibility somewhat.

What we generally do not is insist that the contractor submit shop drawings, not start fabrication until the designer reviews the shop drawings, and then not take any responsibility for the review, delay and costs.

Remember in the Hyatt Regency disaster, the shop drawings were reviewed and the change in the design was not caught. The designers tried to avoid any responsibility for this because their standard line was that the review did not authorize any changes to the design.

The problem was a long threaded rod was called for in the design. This rod was to have been several stories in length. There were several walkways that were to have been hung from this rod. With a single rod the nut and washer supporting the walkway had only one walkway supported by it.

The shop drawings showed that the rod was split at each walkway. A new rod was then started and supported the walkway below. This resulted in each nut and washer on the bottom of each walkway supporting all walkways below it. There was no additional stiffening of the bearing surface to accommodate this load.

The top walkway gave way when the beam yielded at the bottom flange where the entire weight of the lower walkways was held. This started a cascading failure as the walkway system collapsed. Over 100 were killed.

This is a classic case. The drawings were reviewed. The designer’s defense was that they only reviewed the drawings they did not approve them. Why have the review without assuming some responsibility for the results of that review, unless the real reason is to increase designer’s fees?

Like I said in the original post, I have trouble with the ethics of charging for something and not taking responsibility for that work.


Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion

http://www.kitsonengineering.com

 

[IRstuff]

Rick

Thanks for the information.

I'll have to think upon this some more. While the question of liability can clearly be delineated with proper contract terminology and statements of work, the question of preventing deleterious changes is less obvious, particularly since the prime/sub interface is at the design drawing level.

TTFN

 

[PSE]

It almost sounds like a key features or critical characteristics program would be useful. The control drawings from the architect and designers would identify key or critical elements for the design on their drawings. The shop or fabrication drawings would have to show these elements and highlight them as unalterable without review and approval from the designer or architect.

This is a method I have encountered in the past that worked well in an industrial type setting. I am not experienced in construction and am not sure if it would translate.

Regards,

 

[jbarba]

RDK:

Reviewing shop drawings should be viewed as an insurance policy to catch pre fabrication errors. My industry does this to avoid delays in schedule. It is not intended to assume design liability but rather conformance with the initial specification. The manhour investment more than offsets the cost impact for lost sales, construction claims, etc. You could go back to the fabricator error in fabrications but I think you will find that the losses always exceed the value of the item. Unfortunately some fabricators, assuming the buying organization is review their drawings, does not do the best checking job possible. Common sense needs to prevail.

 

[RDK]

Again, I have never said that shop-drawing reviews did not serve a useful purpose.

What I did say is that if we are going to insert a mandatory delay in the process and collect a fee for the reviews of the shop drawings, then we should take some responsibility for the outcome of the review.

Some silly shop drawing practices that I have seen.

1) Contract drawings returned as shop drawings and rejected as not in accordance with the contract.
2) Work held up because the designer wanted to review the shop drawings for some standard municipal sewer pipe. The manufacturer was one of the two listed in the specifications as acceptable suppliers.
3) Significant changes to the contract made by way of red ink on shop drawings returned, with the denial of any additional compensation to the contractor.
4) Significant reductions in the contract made by way of red ink on shop drawings returned with the demand that the contractor provide a significant credit before the work would be allowed to proceed.

I could go on but you get the picture.

Items 3 and 4 were the same designer.



If we are not prepared to assume some responsibility then I would recommend that as a procedure we adopt the following.

1) Shop drawing submittals will be voluntary.
2) Fabrication can proceed as soon as the shop drawings are prepared.
3) Review will commence as soon as and if the drawings are received.
4) The onus is on the contractor to produce a finished facility on time and in accordance with the contract.
5) Review is solely to provide assistance to the contractor during the process. This would make the review similar to an inspection of the work in progress.



Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion

http://www.kitsonengineering.com

 

[kayah]

Yes, but everyone potentially benefits from shop drawing review, not just the contractor, as jbarba (and others) pointed out.

I am sure that consultants do take responsibility for the extent of the review they conduct, regardless of the small print used - which is why it needs to be clear exactly what is (and is not) being reviewed (and paid for). I don't know of any examples, but am sure there are many out there.

As far as hold-ups are concerned, we usually work on the basis that fabrication can proceed before shop drawings are reviewed, but the contractor bears the risk for any problems on the shop drawings that need addressing later - which I think is along the lines of what you are suggesting.

Sure, there are people that abuse the system, but isn't that the case with everything? I for one will continue to require shop drawing submittal, review them expeditiously, and subsequently assume responsibility for the extent of the review - as outlined on the stamp that goes on every drawing. If used correctly I find this a valuable exercise for contractor, owner and engineer alike. In this relatively closed-circle system there is little scope for abuse. It is how others treat the sitution that leads to problems.

To offer one example we recently reviewed shop drawings for precast sections that are clearly under-designed. Without our review these would have gone to construction - the fabricator may bear the liability but in the long-run everyone suffers.

 

[IRstuff]

Rick,

Your 4 examples all appear to be issues with contract scope and SOW definitions, e.g., format of drawings, duration of reviews, scope of work.

In aerospace, these are all every clearly spelled out in the contract.

TTFN

 

[asdf]

From a Contractor's position... Shop drawings are a necessary evil. We understand the importance of submitting correct and complete shop drawings for review, because we do not want to find a conflict during construction whereby we would lose time or money. My single compliant is that we are more and more finding design problem during the shop drawing development process. It is not at all uncommon to find a lack of detailing and dimensioning, the use of outdated (as in no longer manufactured) or atypical (as in something commonly used in California being specified in Kentucky) components, or that the design was simply not completed (being only carried through to the extent of determining member sizes, connection requirements, etc.). I am sure one component of this problem is the technology allowing plans to be put together faster has out paced the designer. At times, it appears that the shop drawing submittal and review processes are more to finalize designs, than to determine and resolve fabrication and construction conflicts. Redline changes that significantly change constructability and increase fabrication and construction costs, are quickly becoming a primary cause of disputes between the Contractor and the Owner.

 

[jherbert]

Hi,

This is indeed as interesting subject and no doubt subject to different intereptations from all team members. A few comments from the consulting side:

1) 12 years ago as Mech. consultant in UK, "Approval" meant was just that, no idea what the situation is these days.

2) RDK mentioned contract drawings submitted as Shop drawings and being rejected. Of course, contract drawings
are not Shop Drawings. I have had contract drawings re-labelled and submitted as Shop Drawings. These were rejected because designers two line ductwork contract drawings are not Duct fabricator drawings, enough said.

3) Shop Drawing's provide invaluable information to the
entire design team. IMHO, consultant's and designers can't approve shop drawings in the construction environment for a number of reasons:

a) During the procurement process (here in Hong Kong at least) the contractor selects all plant and equipment to meet the specification. Then coordinates bwo's, electrical terminations, locations, steelwork, etc. with all the other contractors. Afterwards, then Shop drawings are prepared and circulated for the team for "comment".

Incidentally, thats why we ask for so many copies, a common contractor compliant.

b) Liability (a major PI issue with increasing insurance costs). Every shop drawing as some element of contractor design, whether it is a MCC relay or revised routing following coordination or ductwork seam. Consultant's can't take responsibility for the contractors design under the limitations of the owner/consultant employment contract. If the contractor wants a design checked he always has the option to pay retain a consultant - does not happen very often.

c) Shop drawings (also named working drawings) are really moving target, forming the backbone for the future AS BUILT drawings.

In the real world they are continously amended as co-ordination issues, change,etc. etc. arise during the project. If any one in the team changes the position of one piece of equipment, perhaps hundreds or more shop drawings from all the various disciplines to be generated, requiring revision, issue and approval. If not revised and issued for approval the consultant could escape liability simply because the installation didnt comply with the APPROVED version, hence forcing an unnecessary paper chase.

d) Consultants "should be" expert designers, and contractors should be "expert installers". If the designer does not finish or complete the design that is incompetence not an excuse to abolish Shop drawings.

e) If the consultant was made responsible for approval and a contractor changed an element of the design, the consultant would have to carry out a design audit to verify
the contractor design or reject the submittal. Even reasonable changes would be rejected because the consultant's time allocation for APPROVAL does not include 100's hours needed carry out design audit.

4) I was thinking about RDK's optional shop drawing idea. And on balance feel that is would be recipe for major problems. I feel many contractors would bothered to produce drawing hence countless clashes and dissatisfaction would result - and probably Delaying the project. I note that that major general contractors insist that shop drawings and annotate in a similar manner to consulatants.
The Shop drawing requirement in the contract is one tool to force a contractor to think about the task at hand. And monitor progress during initialisation phase.

5) I hate generalisations, but here we go...if the contractor prepares shody (I am not talking about appearance I mean content) shop drawings then you can be pretty certain the installation will be sub-standard or late, or both.

6) I don't agree with RDK initial assumpution that the consultant review is a delay to the work. It is part of the overall project plan. Like Utility inspections it is part of the process. Personally, I like to see in advance what I am buying, whether TV, HIFI, etc. In construction we can't see all the elements before we order them, but we can see the shop drawings and visualise the end product.

just my 2 cents worth

Regards,

 

[DRC1]

I have seen everything RDK has said and more. While these problems are not the rule, they are not the rare exception anymore either. Most structural drawings are somehat conceptual, leaving the strucutural steel detailer to complete connections for review by the engineer of record. Often the detailer is not a PE. Even if he was strict interpretation of lincense laws would still require the EOR to review the connections. Hyatt Regency was not a connection failure, it was a failure of an engineering management system.
I think that owners, in their quest to do work "Faster Cheaper & Better" (a difficult goal at best) have pressed engineers to get the work out to bid quickly, and then once it is out to bid have pushed construction schedules such that drawing questions don't have adequate time to be addressed by either party. Further, designers have become more and more generalists leaving detailed completion of the plans to contractors and fabricators.
Shop drawings and their review are nessecary as the are the competion of the design in many aspects of the work. However they do significantly impact the work progress.
I suggest the designer hire the detailer and incude the completed shop drawings in the bid package. This would save a tremendous amount of project time, as materials could be ordered upon award of the contract. Most detailers are free lancers who are hired by different shops. Further most designs do not require super secret shop designs. -This is the reason that most designers give for having the contractor produvce the shop drawings- so the fabricator can use the details he likes best. However probably 90% of the details are standard details. If the fabricator wanted to change some details, he could submit that for review and approval. By having the engineer hire the detailer, he can have more control over the quality of the work, yet have the person who is best trained and practiced in the work perfom it. As for the cost, the owner pays it anyway as part of the construction. I think this would solve a lot of the very real problems that are out there. What does eveyone else think?