Am getting single extruded face and many extruded faces randomly

am creating topography with sandbox from contours. I extrude each face with the same way yet some of them extrude a face with single faces and randomly many faces. Can I control this to make single faces?

It’s not a technical problem, but the way SketchUp works. Learn the basics of SketchUp at about weld and edge properties - soft, smooth.

Just weld the edges before extrude (PushPull).

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Ok, buy why does SU work 2 ways, one face, many faces, when doing the exact same operation on the same model?

So quickly did you follow the tutorials and help in where these things are explained? :slight_smile:
You try to skip some learning steps. I wrote you the solution you have to solve the problem directly, and I also directed you to the place where you can learn to understand why.

You need to learn about weld edges, as well as about the properties of the edges.
Depending on these, you can get different results, depending on what you want.

If you take the time to follow the indicated tutorials, you will understand more easily, these being explained in detail by Eric or Tyson from SketchUp, instead of a few words written in a forum post.

Help center search -

What you’re seeing here - the ‘many faces’ - is the result of a projected texture on your terrain surface. When you extrude, or push/pull the contours up, it’s ‘pulling’ the texture up along the vertical surfaces. if you paint those vertical faces, white say, you won’t see those vertical lines. Try it and report back.