Knowing how to link CAD files in Revit is where many projects start: with a background drawing in place, walls and grids snap to lines that already exist. Done carelessly, though, the background lands in the wrong place, comes in at the wrong scale, or leaves rubbish in the file for the rest of the project.
This article follows the order you actually work in on the 2027 release. To learn modelling and documentation end to end, see the Revit Architecture course.
Link CAD or Import CAD: what differs
The two tools sit next to each other on the Insert tab, and they leave very different traces.
Updating is the crux. Revit reads a linked file again every time the model opens, so the background is always the latest saved version; if the file changes while the model is open, click Reload. An imported file is frozen at the version you imported, as Autodesk's About Linking CAD Files explains. Import CAD into Revit only when you need to explode the linework, and do that in a separate file.
Linkable formats are DWG, DXF, MicroStation DGN, SAT, FormIt AXM, Rhino 3DM and SketchUp SKP.
How to link CAD files in Revit with the Link CAD tool
Six steps for a background drawing.
- Open the view the background belongs in, for example the ground floor plan.
- Click Insert › Link › Link CAD and pick the file.
- Set the three boxes on the left: Colors, Layers/Levels and Import units.
- Set the three on the right: Positioning, Place at and Orient to View.
- Click Open. If Layers/Levels is set to Specify, Revit then lists the layers to tick.
- Type ZF to zoom to fit and check the background against the grids you already have.
| No. | Part | What it does |
|---|---|---|
| 1 | Current view only | Ticked, the link shows only in the current view and behaves like annotation. Cleared, it shows in every view that cuts through it |
| 2 | Colors, Layers/Levels, Import units | Colors offers Invert (the default), Preserve and Black and White; the screenshot shows Preserve. Layers/Levels takes All, Visible or Specify. Leave Import units at Auto-Detect; if the background comes in many times too big or small, insert it again and state millimeter |
| 3 | Positioning, Place at, Orient to View | How the file is placed, the level it sits on, and whether it turns to the view's north |
Layers/Levels is the box most often ignored. Left at Visible, any layer switched off in the CAD file never reaches Revit, as Link a CAD File sets out. Correct lines that are slightly off axis is on by default and straightens lines that are a hair off orthogonal.
Positioning options in Revit, three origins and the 16 km limit
The Positioning box decides where the background lands.
| Option | Result |
|---|---|
| Auto - Center to Center | Puts the centre of the drawing at the centre of what the view shows. Avoid it for repeat links or several files, since the centre is computed at insert time |
| Auto - Origin to Internal Origin | The CAD origin lands on the project's internal origin. The usual choice when the CAD file is drawn around its origin |
| Auto - By Shared Coordinates | Places by shared coordinates, for files carrying real survey coordinates |
| Manual - Origin | The file origin follows the cursor; click once to place |
| Manual - Center | The file centre follows the cursor |
To see why an origin-based option exists, you need the three origins Revit keeps.
| No. | Point | Role |
|---|---|---|
| 1 | Internal Origin | Never moves. Every automatic origin-based placement uses it |
| 2 | Project Base Point | The origin of the project coordinate system, and of level values when the level type reads Project Base Point |
| – | Survey Point | The survey origin for shared coordinates, usually a real marker on site |
In the image, the internal origin is the pair of red and green arrows, and the project base point is the blue circle sitting on it. Internal Origin is not ticked by default, so it does not show. Type VG, open Model Categories and type Site in the search box. Then tick Internal Origin, Project Base Point and Survey Point in the Site category.
| No. | Part | What it does |
|---|---|---|
| 1 | Internal Origin | Cleared, the internal origin does not show. Tick it, along with Project Base Point and Survey Point if they are not ticked yet |
One number to remember: all model geometry should sit within 16 km of the internal origin. CAD files drawn at real-world coordinates often land tens of kilometres away, and Revit then draws them unreliably, as About the Maximum Distance Limit explains. For such a file, place it by centre, or take its coordinates with Manage › Project Location › Coordinates › Acquire Coordinates, then click the CAD background.
After inserting: pin it, query layers and hide layers
Three things to do straight away, in this order.
- Select the background and click Pin. There is only one background, and nudging it a few millimetres puts everything modelled afterwards out of place.
- Click Query on the Import Instance panel, then click a line to read which layer it belongs to.
- The Query dialog itself offers Hide in view and Delete for the layer you just read.
To switch off many layers at once, type VG, open the Imported Categories tab and clear the CAD file's layers there. Working that dialog is covered in how to hide elements in Revit.
Manage links and delete CAD link in Revit
Every linked file in the project lives in one dialog: Insert › Manage Links. The 2027 release has no tabs here. CAD files sit in the CAD Formats group; to filter, pick CAD Formats in the Type box.
| Button | What it does |
|---|---|
| Reload | Reads the source file again, for when the CAD drawing has just been edited |
| Reload From | Click the drop-down arrow next to Reload › Reload From. Reads from another path, for when the file has been moved |
| Unload | Drops the background from the project but keeps the path, ready to load again |
| Remove | Removes the link from the project for good, leaving it as clean as before |
| Import | Turns the link into an import, which is best avoided |
The status column says whether the file is still there. A renamed or moved file reads Not Found, and the cure is Reload From pointed at its new home.
An imported file behaves differently: deleting the geometry removes the lines, but the line styles and patterns it dragged in stay in the file. Clearing those needs Manage, then Purge Unused.
Revit CAD link not showing or sitting in the wrong place
This is the most common group of problems, and it is nearly always one of five causes.
Do not fix a misplaced background by exploding it and editing by hand. A linked file cannot be exploded, and Revit refuses to explode an import that would yield more than ten thousand elements, as Explode Imported Geometry notes. The right move is to remove the link and insert it again with the correct positioning and units.
Insert image into Revit, and PDF drawings
A DWG is not always available. A scanned drawing or a PDF still works as something to trace over.
The Link panel of the Insert tab holds Link PDF and Link Image; the Import panel holds Import PDF and Import Image. Choose the file, pick the page and resolution, then click once to place it.
Images and PDFs carry no line data the way a DWG does, so they are only something to trace. Once placed, compare a known dimension — a structural bay, say — and scale the sheet to match before drawing anything.
Try it: bring a background drawing into the project
A background for the ground floor plan. Work in a project that already has grids and levels.
- Open the ground floor plan and click Insert › Link › Link CAD.
- Pick the DWG. Set Colors to Black and White, Layers/Levels to All and Import units to Auto-Detect.
- Set Positioning to Auto - Origin to Internal Origin, Place at to the ground floor level, and keep Orient to View. Click Open.
- Type ZF and check the background against your grids. If it is off, use Move so grid 1 and grid A of both drawings coincide.
- Select the background, click Query and pick an annotation line to read its layer. Hide that layer in the view.
- Select the background and click Pin. Try to drag it and confirm it no longer moves.
- Open Manage Links, click the row in the CAD Formats group, and note the status and the saved path.
- Save the project. This background is the base for every wall and column modelled next.
Grids and levels come before the background, not the other way round. Setting them out is covered in levels and grids in Revit.
Frequently asked questions
My imported CAD file does not show. What should I check?
Five things in order: the Current view only box, the Place at level, Layers/Levels left at Visible, a wrongly guessed unit, and a CAD file drawn at real-world coordinates far from the origin.
How do I delete a CAD link cleanly?
Insert, Manage Links, select the row in the CAD Formats group and click Remove. For an imported file, delete the geometry and then run Purge Unused to clear the line styles.
Should I explode a CAD drawing?
No. A linked file cannot be exploded, an import that would yield more than ten thousand elements is refused, and exploding leaves thousands of loose lines to manage.
Can I insert an image and trace over it?
Yes, with Link Image or Import Image. An image is only something to trace, so scale it against a known dimension and pin it.
Related articles
- Levels and grids in Revit — the positioning system to set out before linking a background
- How to hide elements in Revit — switching CAD layers off on the Imported Categories tab
- Exporting Revit drawings to CAD — the other direction, Revit out to DWG
- How to create walls in Revit — modelling walls over the background you have just linked
- Revit project units and templates — the project units behind the Import units box