The 10 Worst Things You Can Do In Revit
Revised December 17, 2009
The information contained in this document is time-sensitive as the technology and system requirements continually evolve.
The Autodesk Revit family of products (Architecture, MEP and Structure) presents new opportunities and
challenges to designers. Revit concentrates all information in one central model database rather than
several drawing files. Because every designer uses and shares the same central Revit file, problems created
by one user will often affect all users. Revit models also contain far more information than just geometry;
hence the term Building Information Modeling. Revit, of course, is not simply an AutoCAD upgrade and we
are learning how different it is every day. These are some of the lessons we’ve learned supporting designers
using Revit.
1. Never leave inserted AutoCAD DWGs in a Revit model. Although you can insert a block or drawing into Revit it can cause severe performance and stability issues. DWG files bloat the model by using
far more memory than pure Revit entities. Also, AutoCAD DWG files can corrupt the file, causing
internal errors, excessive warnings, and language barriers, which slow down the performance of the
model. We recommend that you recreate your favorite blocks as Revit Families. If you must insert a
DWG file for tracing or reference, purge it as soon as possible. Regularly check the model for blocks
and DWG files to make sure it stays lean. Never explode DWG files that have been imported into
Revit as this makes the problem worse and more difficult to resolve. It also, can make the issue a
permanent one as some elements, once exploded, can never be removed. If the AutoCAD file is
necessary as a background, linking the file in rather than importing it can prevent and reduce some
of these issues.
2. Don’t let unresolved Revit warnings languish. Large numbers of unresolved warnings can seriously
degrade model performance and stability. Resolve warnings as they occur to keep them from
building up in the model. Periodically check the “Warnings” tool on the “Modify” ribbon to see what
warnings (if any) have built up in the model.
3. Don’t use Revit Families from Manufacturers without checking them first. Building Product
Manufacturers are responding to your requests for Revit content by having families of their
products created in Revit. These families may look great when viewed, but if they contain too much
detail they can quickly bloat your model. One unnecessarily detailed door family could add dozens
of megabytes to your Revit model and slow you down. Additionally, we have found some
manufacturer-provided families include imported DWG files (see number 2 above).
4. Don’t over-model. One of the most common mistakes among new users of Revit is to put too much
detail in the model. Determine how much detail is really necessary to convey your design intent, and
then monitor your team to prevent over-modeling.
5. Don’t use in-place families too often. While it is inevitable that you will have to use in-place families
in a typical project, be selective in their use. If you create an in-place family and later decide that it
should be a component family, there is absolutely no way to convert it. If you must use an in place
family, do not duplicate it. For example, if you have to use in-place families to create light coves in
several rooms, create them all in one in-place family; don’t create a different in-place family for
each room.
6. Don’t over-constrain model geometry in a project file. Dimension and alignment constraints add
overhead to the file and increase the potential for the dreaded “constraints not satisfied” error
message. If you’re not absolutely sure that you should constrain something, then you probably
shouldn’t.
7. Don’t lose control of your views. Exercise good view management. Don’t create unnecessary views
and don’t leave views unnamed. During the course of a project, the project browser can become
populated with a large number of views. Bad naming practices or unnecessary views can make the
view list even more unwieldy. Also, utilize the browser organization tools to your advantage to sort
views in ways that make them easy to navigate.
8. Don’t over-use Groups and Design Options. An inordinate number of groups in a project can impact
performance and bloat the model. Make sure to purge unused groups from the model regularly and
turn off the “Group and Associate” option when using the Array tool. Likewise, be careful not to get
carried away with Design Options which are meant to allow for multiple possibilities for minor
changes in the model. Improper use of Design Options can duplicate many entities and increase
model size significantly.
9. Don’t use Worksets to control visibility. The workset of an object can change at any time and since
there are no rules that say a tree can’t be on a “Roof” workset, for example, it can cause unexpected
issues with object visibility and printing down the road. Grouping can also affect the workset
assignment of objects, causing further problems with this method of visibility control.
10. Don’t create a “Demolition” phase. Demolition is an action and not a phase. While phasing will still
work if you create a “Demolition” phase, it adds one more phase that you have to manage and is
completely unnecessary and redundant
In conclusion, these 10 nuggets should prove very helpful in your transition into the world of BIM
through Revit. In addition though, we offer one thing you should do: read the Revit Platform Model
Performance Technical Note posted to the Autodesk web site. Simply navigate to www.autodesk.com,
and enter “Revit Platform Model Performance Technical Note” in the search window.
Austin
Dallas/Ft Worth
