15 BIM Tips: Avoiding Model Corruption & Optimizing File Sizes

Even some of the most experienced Revit users make mistakes in modeling and model management that can lead to detrimental and sometimes even disastrous results.

In the November Applied Software, Graitec Group Revit Best Practices webinar, Revit expert Matt Dillon shared BIM tips for avoiding model corruption and optimizing file sizes so you can have lean, clean, accurate models.

Avoiding model corruption and data loss.

1. Don’t import DWG files; link them. You can easily remove or unload them when they’re no longer needed.  

If you do it anyway:

• If you consider it necessary to import a DWG, for instance if you’re converting it to a Revit detail, delete it after that’s done. Importing DWGs brings in non-native Revit geometry. Additionally, DWG is not the most stable file format. You could potentially bring in a CAD file with corruption, so delete all the layers to get rid of it.
• If you you do import a CAD file, don’t explode it. When you do, it becomes a multitude of little CAD bits. It’s almost impossible to get those out of your project after the explosion.

2. Don’t delete geometry. Modify it instead. If you have geometry that needs to be changed, don’t delete it. Modify the geometry so it retains its element ID. This is important in case it hosts other objects. If it’s deleted, those objects are orphaned. 

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Optimizing file sizes to maximize performance.

3. Address your warnings as soon as possible. If your model is acting sluggish, it could be caused by unresolved warnings. Revit scans the internal database when you have unresolved warnings; if there are a lot, it can slow down the performance of your model. Although you will rarely have no warnings, you definitely don’t want to have thousands of them. Discipline yourself to address them to minimize them as much as possible. In addition, it’s better to address warnings as they happen. You can watch Matt’s webinar about 14 minutes in, where he demonstrates how to resolve a few warnings. Matt also shared an Autodesk Knowledge Base link where you can access a list of all the warning messages in Revit, what they mean and how to resolve them. 
4. Don’t overmodel. Just because you can model it doesn’t mean you should model it. If you don’t need to render it or schedule it, and it would not be visible at the scale of your primary floor plans, for example, then you probably don’t need to model it.
5. Don’t over constrain model geometry – it becomes model overhead. Leaving things unconstrained is usually a better idea.
6. Consider using symbolic lines and masking regions in component families instead of 3D geometry if the component only needs to be represented in plan, section and elevation.
7. Don’t overuse groups. Arrays become groups by default, and groups cause more overhead. Unused groups should be purged from the model.
8. Don’t overuse design options. They are intended for elements of the model that might need to have multiple options to explore, such as an entryway, bathroom layout, etc., not entire optional projects.
9. Avoid overpopulating templates with pre-loaded families. Only load the ones you will use in every project. Store the rest in an easily accessible, well organized family library. There are a variety of 3^rd party family management tools available.   
10. Limit the use of in-place families. Because each family has its own definition, an in-place family should never be copied. It’s best to use a loadable component family instead whenever possible.
11. Avoid families that cut hosts when possible.
12. Avoid arrays and formulas in families unless you absolutely need them. They increase file size and model overhead.
13. Don’t overuse parameters.
14. Don’t overuse voids.
15. Break large models into separate pieces, for instance separate buildings, towers, parking structures, expansion joints, building core/shell/interiors all make for good ways to break up a model.

With some knowhow and discipline, you can become an experienced Revit user who avoids model corruption and optimizes file sizes for lean, clean, accurate models.

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