Don’t Get Lost In the Details
Details. They aren’t necessarily exciting, but every project has them. In the context of construction documents they are the industry standard method of conveying graphical information at a scale, or level of detail, not needed throughout the whole project. They depict a small area of a building, element, or system. Some details are project specific because they are unique to that project and won’t be reused. Many, however, are so typical and common that they get reused often or on almost every project.
For this reason companies have detail libraries—an entire repository devoted to keeping and maintaining details that will be accessed on future work. They are generic or typical enough that they can be used on projects unchanged or used as a starting point so as to not reinvent the wheel.
Maintaining a detail library can be a chore and even make up a fairly significant proportion of a position’s job duties. Depending on the size of the company (or not!) there may be standards in place on detail naming, location, accessing, proper use, etc. As with anything there are numerous opinions on the approach to details and detail libraries. This is especially the case related to Revit® and the transition from CAD for many companies in the last 10 years.
Because AutoCAD® dominated so much of the AEC industry the last 20-30 years, most details were or are in DWG format. Understandably this is or was an obstacle to be overcome with a transition to Revit. The short answer is that yes, DWG details can be used in Revit projects. The long answer is that no, it is not the best solution. I tend to be a software purist. In my opinion, using DWG details in Revit is a short-term solution to a long-term problem. Let’s discuss some of the approaches and thoughts on the topic of details in Revit.
By now it is probably common knowledge that DWG files can be referenced into a Revit drafting view in several ways. First, they can be imported (Figure 1). This is probably the least desirable option for the purposes of a detail. Once imported, the DWG cannot be edited or updated in Revit or AutoCAD. In order to update the DWG, it would have to be deleted, edited outside Revit, and then reimported.
Figure 1
A second option is to explode the DWG in Revit, converting it to Revit elements (Figure 2). This way the detail can be edited if needed without having to leave Revit. That this option is even available makes many Revit users shudder. Why? It isn’t a very “clean” process. When a DWG is exploded/converted it creates all kinds of text types, line patterns, filled region (hatch) patterns, etc. Cleanup of this “garbage” quickly begins to diminish the attractiveness of this option. Some even report that doing so leaves “invisible” artifacts that can destabilize the model.
Figure 2
Third, a DWG can be linked (Figure 3).This allows the file to be referenced into the model without having to convert it. This is more desirable compared to the first two options. However if it does need to be edited, it has to be opened in AutoCAD®. To see the changes in Revit it must be reloaded through Manage Links. This workflow is not the end of world, but it can be quite inconvenient having to repeat this process as details are edited as the project progresses.
Figure 3
Another drawback to this third option is the appearance of the detail. Some, if not considerable, changes typically must be made to the DWG to ensure that it looks the same in Revit as it does in AutoCAD. Common offenders are items such as text formatting and layers/line weights. Some have outlined a detailed process of making changes to their DWG details by which they were usable—both in AutoCAD and Revit. In the end we decided against spending our energy on this approach and instead on a Revit-first approach, which will be discussed more in depth later in this article.
The last option is to re-create the detail(s) using native Revit elements in drafting views. Admittedly, this option is the most time consuming, but if a long-term solution is the goal, it also produces highly editable and usable details in Revit. I am partial to this last option, but because this process takes the longest, linking in DWGs is a good solution to bridge the gap.
As we have seen, there are several factors to consider when thinking about details in Revit. Given the various scenarios a company might encounter and the desired goal, there is more than one path to a solution. There are also numerous software programs to help with the various aspects of such a project, like conversion, file management, and accessibility for companies with distributed offices and team members. Below, I’d like to recount a recent conversion project outlining the decisions and steps that were made.
Our office has decided to pursue using Revit as much as possible, even on “CAD” projects. Coinciding with that decision it also made sense to fully convert an entire detail library of more than 1,000 details. The process from start to finish took approximately two years of on and off work. Where possible, details were converted as needed on live projects. When time allowed, hours were devoted solely to converting details in the library.
In terms of the actual conversion we tried several approaches. Converting a large number of details is a sour pill to swallow. There are really only two tools native to Revit to assist in the process. First is simply choosing to explode a DWG file. Due to the disadvantages described above if this method is chosen, it is recommended it be done in a non-project or non-template file. Once conversion and further changes are made, the elements can be copied and pasted into the model or template where the details will live or be used.
If attempting this approach, something to consider is linking several DWGs in the same drafting view. This way the explode, and subsequent cleanup, can be done on all elements instead of one at a time on individual details in their own drafting views. There is a limit to the number of elements that can be exploded—I think the number being 10,000 that will throw a Revit error.
Additionally, this method can reveal poor drafting techniques in the DWG, such as overlapping lines, exploded hatches, etc. To my knowledge, exploding a DWG is the only process that converts text. It is also converted in a way that preserves appearance, not formatting. This means multiline text is converted to individual text elements. Dimension text is converted, but the dimension line work itself is just lines.
All things considered, that is why experience has made me conclude that in the end the best way to convert a DWG detail is to redraw it in Revit. The second Revit tool that can moderately assist with this is the Pick Lines tool (Figure 4). Desired lines in the DWG can be selected or, using tab, chains of select connected linework will be converted to the desired line style.
Figure 4
We did make use of some helpful macros and add-ins to assist in the conversion process. “Convert DWG to Revit lines” from ArchSmarter.com allows layers in the DWG to be mapped to Revit detail lines, converting every DWG line in the view without having to manually pick them. Again, this process is as “clean” as the DWG itself. We used another add-in from the Autodesk Exchange Store that removed overlapping detail lines, the equivalent of the Overkill command in AutoCAD. Filled regions (hatches), dimensions, and text had to be manually entered. Perhaps it goes without saying that detail item and generic annotation families can be created for use across the details for various purposes.
Another aspect of this conversion project was the decision to keep all the details in a single Revit model. This allowed Revit’s capabilities to make tasks such as editing view names, text notes, and families a breeze. Need to change the font of text? Edit the text types and the change is made to every detail. Want to find and replace words in text notes? Use find and replace to search all text throughout the whole model. Lastly, by keeping all details in a single model, detail(s) can be easily found and inserted into a project model as needed using “Insert from File” (Figure 5).
Figure 5
For projects in AutoCAD, details can be exported from Revit to DWG. By editing the export to DWG settings, layers and other items can be configured and applied. Just as conversion from DWG to Revit has its downsides, so does exporting from Revit to DWG. But for our goals and purposes it made the most sense to make Revit the source format for our detail library.
Figure 6
Because Revit is not backwards compatible, a challenge to consider is how to make details available to multiple versions of Revit. Due to improvements in the text editor, it was decided that Revit 2017 would be the lowest supported Revit format for our detail library. A copy of the library was upgraded so that all details were available for each subsequent version.
A final aspect to consider for our situation was the need for details to be available in PDF format. There are content management solutions that help with nearly every aspect of detail library management that have been described so far. But these have additional costs, and not every company has access to in-house software development. Something nearly every business probably does use, though, is Microsoft software, most recently Office 365, which comes with Sharepoint in the cloud. This is where it was decided to house our detail library in PDF format. The latest details are accessible by team members in any office anywhere in the world. Using search and metadata for filter controls details can easily be viewed and selected by anyone with a web browser and Internet connection.
Figure 7
Maintaining a detail library is a necessity in our industry. There are many ways to meet this need while maintaining standards and improving efficiency. What option is best for your situation depends on several factors that may change over time. Either way, with proper planning there is no reason to get lost in the details!
Nathan Mulder has more than 10 years of experience in the AEC industry. He is currently the BIM and CAD Manager for Guidepost Solutions, a global leader in investigations, compliance, and security consulting, offering design services for security, telecom, and technology systems. A Revit MEP Electrical Certified Professional, Nathan is always looking for ways to fully leverage software to improve the project design and management process. Contact him at mulder.nathan@gmail.com or on LinkedIn.
