How to split this surface?


So I am following a youtube tutorial.
The guy draws a rounded shape on the land, which immediately becomes its own independent shape upon completion.

lWhen I draw the shape in Sketchup Pro 2021 (last image), it does not create an individual shape, it remains a drawing on the ground, and I can not extrude it or assign any material to it as a result.

Redid this 4 times now and it’s not working. I tried connecting the 2 end points with a line, it makes no difference.

Anyone know what’s wrong?

It would help if you share the .skp file so we can see exactly what you’ve got. Normally when you have a thick profiel edge on a surface and the surface isn’t divided into regions, either edges don’t form a closed loop or the edges aren’t entirely on the surface. Neither one of these would be a bug in SketchUp.

Here is the file:

There are several issues here. First you should be using groups and components to keep the building separate from the ground. Here you have the majority as loose geometry.

I copied the ungrouped geometry in your model and eliminated all but the ground and the outline. you are concerned about. I also cleaned up some stray geometry (look at the bottom of your model). Then I was able to close the loop properly and divide the large rectangle into two regions. Note how the edges bounding that inner region are no longer thick profile edges.

My suggestion would be to delete the ground and any loose geometry that is not the house and then make groups for the walls and other structure related parts. Then redraw the ground and group it separately so it can be worked on.

BTW, I fixed incorrect tag usage in your model. ALL edges and faces should be created and left untagged.
Screenshot - 2_13_2022 , 8_39_56 AM

I also purged unused stuff from your model. This is something you should do on a regular basis. You can use the Purge Unused button in Window>Model Info>Statisitics. This reduced the file size by almost half.
Screenshot - 2_13_2022 , 8_40_46 AM

A number of the components you’ve collected from the 3D Warehouse could do with a diet. A number of them are overly detailed for the small part they play in your overall model.


Hello Dave,

thank you very much for your input.

As a new user, this is unfortunately hard for me to understand, so I will have to first learn more by doing more tutorials and then revisit this project later.

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That is a good idea. Start with much simpler projects to learn the basics. Go through the tutorials at as a beginning.