Cost of Working Drawing Preparation 3

[jfw04]

I am doing some market research and I had a few questions as far as the cost of shop drawing preparations. If anyone has an idea on any of the questions below I would be very grateful, rough estimates are more than enough.

What is the average cost of shop drawing preparation for structural steel shop drawings based on square foot of building or steel tonnage?

What is the average hourly rate detailers charge?

Is there a substantial difference in that rate between detailers using CAD to create shop drawings and those using a 3-D BIM model?

Is it becoming common practice for a structural detailing firm to purchase a BIM model from the engineer of record to use in shop drawing preparation?

If so what is the average purchase price in percentage of typical shop drawing preparation cost?

 

[Brad805]

I can address a couple of your Q's:

The average cost per tonnage will vary depending upon the job complexity. I know of one detailing firm that charges up to 10% of the steel cost for complicated projects. If you go overseas the rates are a lot less and they are based solely upon the tonnage.

I do not believe you will find a large price difference between 2D cad drawings and 3D. I do not know of many shops using 2D cad anymore given the degree of automation that most shops are going to. There is a lot of information that you cannot produce cost effectively with 2D cad.

I can't imagine a time where the EOR will be paid for BIM models by a fabricator. It sounds like a great idea, but the reality is that most EOR's will not be able to produce the information needed by the fab shop. Starting with a 50% correct model is more work for them than starting from scratch. It does not take a lot of time to re-produce the basic skeleton of a building. Most fab shops are going to automated lines (automatic cut lines, CNC..) and require special output from the BIM model. If they start with a poorly numbered job or incomplete model it can be time consuming to correct.

I know of one shop that complained to us about models they have received. They mentioned that these models contained far too many errors and the models were only used as a quasi reference only. On the other hand, we recently shared a complete model with a fab shop and they were very pleased to have our model. They added some phases, renumbered the elements according to their standards, and submitted the model to us for review. That said, they probably would not have paid for it. Unless the fab shop is aware of what you can provide, I suspect they will be very reluctant to pay for a model.

Are you an EOR considering BIM?

Brad

 

[jfw04]

I work for a structural consulting firm, EOR, who is starting to use BIM (Revit Structure in particular) and we are looking into the possibility of selling the model we create to the contractor or fabricators for shop drawing preparation. We are also looking into the possibility of using Structural Detailing in combination with Revit Structure to produce shop drawings ourselves.

I guess my thought would be if the model was created with an appropriate level of accuracy a fabricator or contractor might be willing to purchase it to combine other models for shop drawing preparation, material take-offs, collision detection etc. I imagine there is a large amount of overhead in taking 2-D contract documents and trying to create a 3-D model from scratch, especially if it has already been created. It seems like a waste to me. Although, I do agree with you that a model that is set up poorly would be harder and more time consuming to fix than just starting from scratch.

 

[Brad805]

I think you should survey the local fabricators to see if any in your area are using Revit. I doubt many are. Most use Tekla Structures (TS)(formerly XSteel) or StruCad. Also check to see if Revit can write all the files they need (Fabtrol is one that I bump into). Without those, you might not have not have great luck selling the models. If you have companies only need 2D drawings, then the detailing services will be an option for sure.

There is always the option of interchanging information using IFC protocols, but it is not always a smooth translation (or complete)like all the salesman would like you to believe.

I know many TS detailers that start out with Revit models, but I doubt they are paying for the base model. You really need to be clear in your contract who owns the model.

I know Thorton Tomasetti (using TS) is doing what you propose, but I think they clearly market the services separately. EOR for owner, detailing services for the fabricator. I am sure they can offer a better price for the detailing services, but I don't think they are selling the models without doing the detailing.

You will have to do a little experimenting with Revit to see how fast you can generate a complete set of shop drawings. There is a reason Revit is a lot cheaper than TS. TS has routines to automatically generate (or clone) part drawings, and I am not aware that Revit does. I also do not believe that Revit has the same custom component features that greatly expedite detailing a complete building.

It is going to be interesting to see how BIM evolves. Most EOR's cannot get past the liability issue, so I have not seen a lot of model sharing yet (in Canada anyway). There are some really great benefits of BIM if everyone works as a team (owner, EOR, GC, subs), but it is difficult for many to get past the concept of worrying about anyone but themselves.

Brad

 

[jfw04]

You bring up some good points Brad, thank you for all the information.

 

[francesca]

If the EOR is paid to develop the model by the client it is unethical to sell it to the fabricator. It is being paid twice for doing the work once and it's grounds for losing your license just about anywhere.

 

[jfw04]

What if additional detail is added to the model purely for the benefit of the fabricator for use in shop drawing creation. I would view that in the same was as charging for shop drawings the same firm created with its own model. While some of the initial effort is already complete, (which allows your price to be more competitive) there is additional effort spent in the actual detailing process which I think would warrant a fee.

 

[Brad805]

All of the work is being done to benefit the owner. We are talking about two separate options. The first is selling the model to a fab shop. Should it be given to them for free? That depends upon the model ownership defined in your contract. I still maintain that it is unlikely that a fab shop will pay for this from any EOR unless that EOR also offers detailing services. The second option is if the EOR uses this model to create the detailed shop drawings. In that case, I do not see a problem with you using this advantage to bid to the fab shop provided your contract does not have any terms that prevent you from doing so (ie. owner maintains ownership of said model). At the end of the day the owner will benefit from this model and your providing it to the fab shop can greatly improve project schedules as was the case in the New York Stadium.

Model ownership and model control is one of the fundamental hurdles facing the industry to make BIM effective. Is it the arch, eng, owner or even a new separate modeling service that owns and maintains the model? My view is that by the time all the eng's and arch's get done squabbling over model control and liability issues, the detailing techs will have taken over and created a modeling service that will give the owners full control of their models. It is not much of a leap for detailing firms to expand their services to include complete services. They already have the right tech's and the basic setup. The steel detailers are 15years ahead of EOR's in BIM and facility management using BIM is a new market that is highly anticipated by many.

Most of the high tech clients seeking BIM services carefully define the model ownership terms. Those that do not define this item probably do not understand the benefits and probably will not pay anymore for BIM vs. 2D. In the later case (most of our clients) BIM is mainly an internal QC method.

Brad

 

[Bobber1]

I like the idea of the detailer building the BIM model. But do they in turn coordinate with the other team members for clash detection, mechanical & plumbing routing, etc.?