Surface Border problem . .

I am having ‘surface border’ problems. Even the simplest single, isolated rectangle drawn by itself shows the ‘surface border’ red edges when examined with Solid Inspector2.

How does one correct this? Hasn’t happened before at such a simple elementary level.

Any advice will be appreciated!

Sketchup Pro 2018 with Mac (Mojave).

A simple rectangle will always show as a surface border, it needs thickness to be seen as a solid.


A “surface border” occurs wherever an edge has only one face using it. It either bounds a hole between the interior and exterior of a candidate shape or is a flap with no thickness. Neither of those is permitted in a solid. To correct it you must eliminate such flaps and draw additional edges to create a face that closes each hole. Analyzers such as solid inspector can’t do the repairs automatically because they can’t be certain what you really intended.

Thanks. I think I’m catching on!

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