Stray edges in SketchUp: how to find and delete them
Stray edges are loose lines that don't border any face. They're usually left over from modelling, and you can select and delete them. A face won't fill in when its outline has a gap, isn't flat, or has edges split between a group and the model; close the gap or flatten the loop, then redraw one edge with the Line tool.
What stray edges are
An edge in SketchUp normally borders one or more faces. A stray edge borders none. You get them when you erase a face but keep its outline, draw a reference line with the Line tool and forget it, or import CAD linework.
Not every loose edge is a mistake. Section outlines, 2D plans, text drawn with lines and wireframe details are loose edges on purpose. Check before you delete.
How to find stray edges
Stray edges look exactly like the edges of faces. Ways to make them stand out:
- Orbit around the model. A line floating in the air, or poking out past a corner, is usually a stray.
- Double-click the edge with the Select tool. That selects the edge with the faces it borders; if no face highlights, it borders nothing.
- Turn on endpoints. Open the Styles panel (from the Window menu), open Edit, then Edge Settings, and tick Endpoints. Line ends get thicker, so short leftovers and broken lines show up.
- Check inside groups and components. Strays often hide inside a group. Double-click it to edit, then look again.
How to delete stray lines
Select the edge and press Delete, or click it with the Eraser. To clear several at once, hold Shift with the Select tool to add each one (Ctrl on Windows or Option on macOS also adds), then press Delete.
Take care when you erase an edge a face depends on: delete one side of a face and the face goes with it. If that happens, press Cmd+Z (macOS) or Ctrl+Z (Windows) to undo.
Why a face won't fill in
SketchUp only makes a face when the edges form a closed loop and every edge lies in one flat plane. When a face won't fill in, one of these is usually true:
- There's a gap. Two lines look joined but their endpoints don't touch. Even a tiny gap stops the face.
- The loop isn't flat. One point sits slightly above or below the others, often after tracing an imported plan or a photo.
- The edges are in different places. Some edges are inside a group and the rest are loose in the model. SketchUp can't fill a face across a group boundary.
How to make the face fill in
- Close the gap. Zoom in on each corner and draw a line from one endpoint to the other, letting it snap to the endpoint.
- Redraw one edge. Draw a new line over an existing edge, endpoint to endpoint. That often makes SketchUp check the loop again and fill it.
- Test for flatness. Draw a diagonal across the loop. If the two halves fill, the original loop wasn't flat. Turning on Color: By Axis in Edge Settings also helps: an edge that leans off an axis stops showing the axis colour.
- Put the edges in one place. Explode or open the group so every edge of the loop is in the same context, then redraw one edge.
How Lookover finds and fixes stray edges
Lookover's stray-edge check finds lone leftover edges and leaves deliberate linework (plans, outlines, line drawings) alone. Fix it erases only those edges, in one undo step.
Related checks catch extra edges that split one flat face into two, and edges too short for SketchUp to work with. Each has its own one-click fix. Lookover doesn't fill missing faces for you; it points you to the problem, and the steps above still do that job.
Questions
Does Purge Unused remove stray edges?
No. Purge Unused (Window › Model Info › Statistics) clears out unused components, materials, styles and tags. Loose edges are geometry in the model, so you need to select and delete them.
Why do stray edges matter if they're small?
They clutter the model, catch your next line's snapping, and can stop a model from being a clean solid for 3D printing.
Can I safely delete every loose edge?
Not always. Plans, outlines and line-drawn details are loose edges you meant to draw. Check each edge first, or use a tool that leaves connected linework alone.