D&C (Design and Construct) form of documentation in Revit

[Michael.c]

Hi...I'd just like some opinions here.
Does anyone have any thoughts or ideas or general comments on the process by which projects are, or may best be documented, to this this form of contract, specifically in Revit.

I am talking about the level of detail where:

a) much of the services would traditionally be represented in a single line

b) rather than detail everything, notes are used to refer to services that are similar to elsewhere in the project

c) The final co-ordination is left up to the contractors to sort out, so providing what are essentially our 'schematic' layouts work with a little tweaking here and there, we can say that we have earned our fee, and....

d) .....our fee and the time frame that we have been allocated to do the job is reflected in all of the above!

To me, Revit simply does not lend itself to this type of work. It is quite simply the wrong tool for the job.


I freely admit it....I'm struggling with this concept. Am I suffering alone?



Thanks


Michael

[mattw]

We do just about everything you described. We don't model every little valve, connection point, etc. because there simply isn't enough time and frankly, there's no point. For example, when we model plumbing piping to a sink we only bring the piping up the to wall because A) we can't connect to an architect's plumbing fixture through a linked model B) we aren't going to copy/monitor every fixture/device the architect has in their model (it just doesn't make sense to) and more importantly C) we have typical details and specifications that tell the contractor/installer/whoever how to connect the pipe to the sink. We're not going to model a P-trap just because Revit gives us the ability to do so (just because you CAN in Revit, doesn't mean you SHOULD). Besides, what would you do when the architect invariably decides to move the sink? You then have to move/remodel your piping. When you're just showing the piping up to the wall, the amount of time it takes to make this sort of change is matter of seconds as opposed to a matter of minutes or even hours, which over the life span of a project can really add up.

To make a long story short, we model all of the big stuff (mains, cable trays, drainage piping, etc...) to a point where we're confident it'll fit. A lot of the smaller stuff like 3/4" supply lines for example, most of the time we'll do those as detail lines because we know, heck EVERYONE knows, that it'll fit. Things like that however, are typically flushed out at the project kickoff meeting so the architect and other engineers know what they can expect from our model(s).

[mhartmann]

the BIM kick-off meeting is key (before anyone starts). determine scopes, standards, who's modelling what, levels of detail, push for extra time and fee if it's more than you've budgeted... and find out who's doing what with the models, navis coordination, fabrication, owner FM... it might affect how you do things
hth,
mike

[AaronC]

We do just about everything you described. We don't model every little valve, connection point, etc. because there simply isn't enough time and frankly, there's no point. For example, when we model plumbing piping to a sink we only bring the piping up the to wall because A) we can't connect to an architect's plumbing fixture through a linked model B) we aren't going to copy/monitor every fixture/device the architect has in their model (it just doesn't make sense to) and more importantly C) we have typical details and specifications that tell the contractor/installer/whoever how to connect the pipe to the sink. We're not going to model a P-trap just because Revit gives us the ability to do so (just because you CAN in Revit, doesn't mean you SHOULD). Besides, what would you do when the architect invariably decides to move the sink? You then have to move/remodel your piping. When you're just showing the piping up to the wall, the amount of time it takes to make this sort of change is matter of seconds as opposed to a matter of minutes or even hours, which over the life span of a project can really add up.

To make a long story short, we model all of the big stuff (mains, cable trays, drainage piping, etc...) to a point where we're confident it'll fit. A lot of the smaller stuff like 3/4" supply lines for example, most of the time we'll do those as detail lines because we know, heck EVERYONE knows, that it'll fit. Things like that however, are typically flushed out at the project kickoff meeting so the architect and other engineers know what they can expect from our model(s).

This is a GREAT point and a great lesson learned for us. DON'T OVER MODEL!

[Michael.c]

Mike, Matt, Aaron...thanks for taking the time to respond. My question hasn't really been answered though....my fault, perhaps I could have worded it a little better.

More and more these days, having provided the contractor with a basic single line duct or pipe or cable tray or whatever layout, we leave final sizing and intricate co-ordination up to him. Our documetation shows the general design intent, the number of systems, perhaps the type and number of air outlets, the approximate routing of services, etc. This along with our schematics is deemed to be sufficient for a contractor to price, and for us to justify our reduced fee.

Commercially, we need to stick to this level of detail and not exceed it if we want to meet our deadlines and avoid blowing our fee. The point I was trying to make is that to achieve this, Revit is NOT the ideal tool for the job. With Revit, you can't simply throw in a few single lines to represent the approximate routes of pipes and ducts, etc, and get the job out the door. Everthing immediately has a size, a level, not to mention all the intelligent information that goes into it, and it becomes part of a model, a model which no doubt the architect will want to link into his model.....to.....CO-ORDINATE with.....which means that......we should probably make sure it is as co-ordinated as possible ourselves before it gets to him.....which means....time and money!

One thing I am certain of is, that it is not the way Revit and BIM is intended to be used....of that there is no doubt in my mind. Any Autodesk reps out there care to answer that?


Thanks,


Michael

[DaveDH]

Actually, with Revit you CAN just sketch a few single lines for approximate layouts. Just don't model anything and use the basic drafting tools in Revit (detail lines, annotative symbols, text, etc.) But as you mentioned, Revit isn't the ideal basic drafting tool, AutoCAD is a more efficient drafting tool.

However, Revit IS intended to be a design tool, and after we started exploring Revit's features we found efficiencies that made up for its less-than-ideal basic drafting - live schedules & equipment tags, managing sheets, 3d coordination, and eventually some of the higher level system development features. It shifts some of the engineer's information management tasks to the drafter and reduces the chances for error since most of the information is (ideally) contained in a single file. (example, 53 VAV boxes and their tags, live on the plans). Also, we found we could extract information from the model that normally the engineer would have find out by sitting down with paper plans and a scale (or drawing polylines in ACAD).

But, from a profitability standpoint, it boils down to what mhartmann mentioned - clarifying and communicating, up front, expected deliverables and how the Revit file is going to be used by the client.

Another thing to consider is the learning curve and level of comfort with the drafting tools. For example, I would rather do basic drafting in Revit than in AutoCAD, mainly because I'm used to how Revit handles snaps, connecting lines, aligning text, blocks/families, etc. Every once in a while I'll help out on an AutoCAD project, and I find that I have to fumble around a bit before I remember how AutoCAD works.

[stimmo520]

Detail lines, and key notes....use generic equipment. We have done a few of these...but I would like to be able to generate a 2-d schematic from a 3-d model...not yet though. Oh well...it can be done, but could be done quicker with autocad, unless youre proficient in Revit drafting.

[rrubert]

No, you are not suffering alone, and no, I don't think Revit is the best tool for the level of detail you indicated.

I'm not from Autodesk, but my guess is they'd argue with you that you CAN do all the stuff they advertise Revit as being able to do in a faster time frame and under budget. I personally do not believe this is necessarily the case, or that it's a moot point because, as you said, you don't WANT to do all the things Revit is advertised as being able to do.

Kind of frustrating, I know.

[Michael.c]

No, you are not suffering alone, and no, I don't think Revit is the best tool for the level of detail you indicated.


Kind of frustrating, I know.

Frustrating...yes, very frustrating indeed!
For the type of work we do, and in the time frame that we have allocated to do it, and for the amount of money we are paid by our client, Revit is not only not the right tool, but it is making our task considerably harder and more complex.
I used to think that using Revit was akin to driving a Rolls Royce 50 metres to a corner shop and back, just to buy a pint of milk. Now I believe it is more like buying a clapped out old Datsun....which will break down numerous times on the way, or worse still, not even get there.