Revit and Level of Development (LOD) 1

[archeng59]

I have been using Revit for several years. I recently started two projects that required a level of development 3 for modeling. I'm finding it's taking many more hours to model detailed connections and other elements in Revit if LOD3 is required. The clients want cold-formed metal trusses to be modeled so they and the mechanical engineers can route ducts and other components through the trusses. Curious how other firms are doing LOD3 projects in Revit? How much do you model for components like trusses, various connections for steel-to-steel, framing bearing on CMU, wood-to-wood connections using Simpson type connectors, etc. The hours required for LOD3 appears to be between 2 and 3 times for a LOD1 (just modeling basic components) project.

 

[phamENG]

Never heard of LOD levels, but makes sense. Are they well defined in an industry document somewhere?

I would push back on modeling trusses unless you're designing them yourself. If you're not, then figure out a reasonable web spacing and give them a box they can run through. Or have them bring a truss designer on board early to give you preliminary profiles that can be used in the model.

For what it's worth, my MO is to model basic components and then use detail components in views on sheets. I don't model each connector or bolt. That would be insane.

 

[Celt83]

LOD 300 is pretty typical.

This is a good spec guide on what the different LOD's are with examples: Link

GSA has them defined similarly: Link

For LOD 300 a cold-form or wood truss would be modeled as a solid element with the proper width and depth to match the truss volume. LOD 350 and higher is where web members would be modeled in my market sector the GC's usually hire a third party to model at LOD 350 and higher for use in clash detection. Should also mention we do not share our Revit model beyond the direct design team, contract documents are the printed PDF sets.

 

[KootK]

Curious how other firms are doing LOD3 projects in Revit? How much do you model for components like trusses, various connections for steel-to-steel, framing bearing on CMU, wood-to-wood connections using Simpson type connectors, etc.

As an EOR, it isn't even possible for me to operate at that LOD. For the most part, I can't tell the component suppliers where to put all of their webs, bolts etc. If you're an EOR too, it sounds as though you may need to educate your clients on this.

I also find that folks get quite excited about having more detailed LOD's until they weigh the cost (high) versus the benefit (low to zero) of having my team do that and get paid fairly for it. There's a reason that old fashioned 2D print drawings were skillful marvels of Spartan communication.

 

[RattlinBog]

Are you talking about needing fabrication-level of detail? You mention modeling connections. I think that's more like LOD400. [URL unfurl="true"]https://resources.ascented.com/revit/lod-autodesk-revit-and-autodesk-advance-steel[/url]

I've only used it enough to be dangerous, but you may need to look into autodesk Advance Steel for fabrication-level detail with accurate connections. I'm slowly learning it. I have the modeling down, but getting drawings is another challenge. [URL unfurl="true"]https://www.autodesk.com/products/advance-steel/overview?term=1-YEAR&tab=subscription[/url]

 

[Brad805]

There is a reason few detailers use Revit for detailing assemblies. Unless you have all the families it is far too slow. Other packages have much better tools and you can hire specialists to create even better tools so you can model assemblies by changing a few variables. The goals of your client do not warrant you detailing all the connections. I would model only the basic parts to illustrate the problem to the supplier. They will not use your model. I have been provided endless Revit models over the years, and most are useless beyond the basic GA.

 

[bones206]

Some good tips here specific to cold-formed framing, but the same concepts apply to other materials:

https://www.structuremag.org/?p=24784

 

[phamENG]

This is a good spec guide on what the different LOD's are with examples:

Thanks for this. I'm taking a couple months off first part of next year to finally formalize my design and documentation procedures so I can start scaling my business, and this will be very helpful.

 

[JLNJ]

We normally work at LOD300 but sometimes bump that up for our own usage. For example if you want the mechanical guys to get a good sense of clear space in a truss to run pipe, then LOD300 is probably not enough for the trusses.

I believe at LOD400 you are looking at modeled connections, etc. Just about fabrication level.

 

[Agent666]

Yeah I think we just model between LOD300 (mostly) to LOD400 (for selected items).

We pick and choose where it makes sense to add a higher level of detailing in the 3D model. For example we often get into trouble on site or in coordination of shop drawings by not modelling items at interfaces between different materials where a higher level of design coordination is really required.

For example I like to see weld plates in precast panels modelled for example, similar for hold down bolts and base plates. Penetrations through floors, walls & beams is another good one that makes sense for us to model.

It's this kind of stuff that warrants more detail in the model from my perspective to avoid coordination issues, and it isn't a matter of modelling more detail for the sake of it, it should have a real benefit for the engineering and coordination of details. Penetrations for example shouldn't be left to just putting one where the pipe is modelled, we often need to be incontrol of this and not allowing the services consultant to make adjustments that might invalidate aspects of the structural design.

We find for engineers/contractors who cannot think in 3D (yes these people they exist) it really helps them visualise what they are designing or building vs some traditional 2D details.

We often provide IFC files for the contractors to utilise. This is a double edged sword depending on your accuracy in the models.

https://engineervsheep.com