To remove diagonal lines in planes of pulled-up gable roof & fascia

Alternately, being able to to create a planar face where drawing suggests one should be-- When I erase those diagonal lines, surfaces disappear.
These diagonals are like auto-folds, but the surfaces are not folded-- how to turn off auto-fold feature, of which I’m vaguely aware?

This isn’t really an auto-fold situation. Very likely not all of the edges are coplanar despite appearing that they are… Can you share an example file that illustrates the problem?

( Moved to SketchUp category. )

This indicates that the surface was triangulated because the “facets” were not co-planar.

Which is indicating that you need to be …

Exactly ! SketchUp is trying to help you. If you have View > Hidden Geometry checked you can see when triangulation happens.

There is no user toggle switch for “Auto-folding”, … besides if you turned it off, the faces would just disappear in the first operation when the points first became non co-planar.

It is really a must to learn how to use double inferences or construction lines to lines up vertices.

If you can’t figure it out, post a screen shot, and better yet, an example model (or part of a model,) that has been purged. (Model Info > Statistics > Purge Unused button)

Thanks for the helpful suggestions and info, Dan.
I probably introduced that subtle, non-planar situation when I pulled that ridge line up—It wouldn’t even do that the night before, and I was excited that it moved at all…
Seems there’s no fix but to start that entity all over again, or to hire a pro!

I would not be pulling UP ridge lines.

I’d first draw the roof outline, then all the vertical gable end faces.

Afterward I would push the largest gable end face across creating the main roof.

Then, push the smaller gable end faces inward until they all hit the main roof edge. Then use the MoveTool to stretch the ridge-line vertex (nearest the main roof) until you get a “On Face” inference upon the main roof face.

Lastly cleanup.

I appreciate your experience n candor, Dan.
I very well may try that-- it was the stretching of the gable roof faces that introduced the next folds, in the fascia, I think.

Your pal, Tom