Start with the outcome, not the command
When someone asks "how do we get our DWG details into Revit?", the honest answer is another question: what does the detail need to do once it is there? A detail that will be placed on a sheet and never touched is a different problem from a detail that will be edited on every project. A detail whose source keeps changing in someone else's CAD system is different again.
Three outcomes cover most cases:
- Reference: the drawing must appear, but the team does not need to edit it in Revit.
- Native, editable content: the detail becomes part of your Revit library and is edited with Revit tools.
- Hold or retire: the detail is out of date, its rights are unclear or nobody can confirm it is still correct.
The last outcome matters more than it looks. A conversion cannot fix a detail whose technical intent is uncertain; it only makes the uncertainty look more official. If you cannot name a reviewer who can approve the content, hold it.
The five routes at a glance
| Route | Result in Revit | Best suited to | Main risk |
|---|---|---|---|
| Link | A reference to an external CAD file that can be reloaded | Content owned and revised elsewhere | Broken paths and unclear ownership |
| Import | An embedded CAD snapshot inside the Revit file | Fixed reference content | Stale content and import clutter |
| Explode | Revit lines, text and fills derived from an import | One-off cleanup trials | Non-standard styles and heavy cleanup |
| Redraw | Native detail drawn to your standard | Complex or inconsistent sources | Time cost and transcription errors |
| Convert with mapping | Native elements using your existing types | Many similar details with a settled mapping | Unsupported entities need follow-up |
Route 1: Link the CAD file
Linking keeps the CAD file external. Revit displays it and can reload it when the source changes. This is the right choice when another party owns the drawing and will keep revising it, for example a consultant's detail or a manufacturer's drawing you are not allowed to modify.
Prepare: agree where the source file lives and who updates it. Confirm units and positioning on a test link before relying on it.
Check: visibility of the layers you need, line weights on a printed test sheet, and what happens on reload after a deliberate test change.
Watch for: a link that works from one workstation but not from another because of a local path. A link is only useful if everyone who opens the project can resolve it.
Route 2: Import without exploding
Importing embeds a snapshot of the CAD file in the Revit project. It travels with the model, which is convenient, but it no longer follows changes to the source. It also remains CAD geometry: you cannot edit it as native Revit lines and text.
Prepare: clean the source first. Purge unused layers and blocks in your CAD application so the import does not bring clutter with it.
Check: object styles created for the import, layer visibility and printed output.
Watch for: imports multiplying across a project. Each one can add layers and object styles to the model. Many firms limit imports in production projects for this reason; check your own standard.
Route 3: Explode an import
Exploding an imported CAD drawing turns it into Revit elements. A partial explode can leave nested CAD content; a full explode converts down to lines, text and fills. The result is editable, but it reflects the CAD file's layers and styles, not yours.
Prepare: work on a copy in a disposable test project. Never explode a detail directly into the shared library or a live project as a first attempt.
Check: which new line styles, text types and fill patterns appeared, and whether they duplicate your standard ones. Count the cleanup time honestly.
Watch for: line style and pattern clutter that spreads when exploded details are copied between projects. Revit also has limits on what can be exploded; linked files cannot be exploded at all. The CAD detail triage guide cites the official Revit 2025 help on these limits.
Route 4: Redraw to your standard
Redrawing means a person recreates the detail using native detail lines, filled regions, detail components and text. It is the slowest route per detail, but it gives the cleanest result and a natural moment to check whether the detail is still correct.
Prepare: have the approved source available side by side, and use your standard template so the redraw picks up the right types from the start.
Check: dimensions and annotations against the original, and a technical review if anything was changed.
Watch for: unintended redesign. Redrawing is not permission to change a construction detail. Record any intentional departures and have them approved.
Redraw is often the right choice for details that are dense, inconsistent or built from many blocks and hatches, and for details where you want to adopt Revit detail components rather than plain lines.
Route 5: Convert with an explicit layer mapping
A mapping-based conversion takes each CAD layer and decides in advance which Revit type it becomes: a line style, a text type or a filled region type that already exists in your template. The result is native content in your standard, created the same way every time.
This route depends on preparation. You need a settled standard, a written mapping and some agreement on what happens to content the converter cannot handle. The layer mapping guide explains how to build the mapping.
Nova Codex is one tool built for this route. It is a Revit 2025 add-in for Windows that reads details saved as DXF and creates native Revit drafting views. Its current coverage, as stated on the Codex page, includes lines, arcs, straight zero-width polylines, simple single-line text, and closed polylines converted to filled regions where the layer is mapped to a filled region type. It does not yet read DWG files directly, and does not convert dimensions, hatches, blocks, multi-line text, circles, curved polylines, splines or paper space. Before anything is created it shows entity counts and skip diagnostics, and a result with unconverted entities is labeled as complete with skips. Processing is local.
Whichever converter you use, plan the follow-up: someone has to add dimensions, replace skipped content and review the result. A conversion is a starting point for review, never a substitute for it.
Choosing per detail
A simple decision sequence works for most libraries:
- Is the content approved and current? If not, hold it until a reviewer confirms it.
- Does the team need to edit it in Revit? If not, link it when someone else maintains the source, or import a fixed snapshot when your standard allows.
- Is the source clean and consistent with your layer standard? If yes, a mapping-based conversion is worth testing. If not, compare a redraw with an explode trial on a copy.
- Did the trial produce an accepted detail within the effort you agreed? If not, switch routes or hold.
Recording the route chosen for each detail, along with the reviewer and date, gives you a migration log you can learn from. After a few batches, patterns appear: certain detail families convert well, others always need a redraw.
Preparing CAD sources before any route
Good preparation in the CAD environment reduces cleanup in every route:
- Work on copies. Keep the original untouched so you can always compare.
- Purge unused layers, blocks, linetypes and styles.
- Move stray geometry onto the correct layers; a layer standard is only useful if the drawing follows it.
- Remove frozen or off layers that should not travel.
- Check units and scale so the detail lands at the right size.
- Delete title blocks, borders and viewport content that belong to the old sheet, not the detail.
- For a DXF-based converter, save a DXF copy from your CAD application and check that the entities you care about are within the tool's documented coverage.
Measuring whether a route works
Compare routes by the total effort to an accepted detail: preparation, execution, cleanup, review and rework. A fast first pass followed by an hour of cleanup is not a saving. Keep notes during the pilot rather than reconstructing them afterwards, and resist turning a handful of observations into a firm-wide figure. Small samples vary.
If you want a ready structure for this comparison, the draft CAD-to-Revit Detail Migration Playbook and free Detail Library QA Checklist describe a repeatable method. Firms considering Codex can review the evaluation criteria and test it on synthetic or non-production details alongside the other routes.
Summary
- Decide the outcome first: reference, native content or hold.
- Link content that someone else owns and revises.
- Import only fixed references, and keep imports under control.
- Treat explode as a trial on a copy, and count the cleanup.
- Redraw complex or inconsistent details, without redesigning them.
- Convert with an explicit mapping when the standard is settled and details are similar.
- Review every result against the same acceptance criteria.