Simple Union Understanding?

Union.skp (229.4 KB)
The attached file represents two walls, adjoining to create a corner. I have tried everything but can not get them to merge and only show their final outline. Instead, they show as two separate entities.

I expect the Tools/Union to create a boolean operation that would make them one properly outlined object. Is this not possible? I have the pro version if that matters.

The groups are not solid. Fill the empty bottom of one of them and the empty edges of the “hole” in the other and Union works just fine.

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In order to use Union or any of the other Solid Tools the objects must be identified as solid. Neither of them are in your model because they are missing faces. The selected one is missing faces in the doorway and the other is missing the face at the bottom.

Fix the groups by completing the faces and then Union will work fine.

BTW, please correct your forum profile. It says you are using SketchUp 5 but that’s not what the file shows.


How do I fix these? I tried the line tool AND the rectangle tool on each corner (endpoint) but it created a separate entity.

Open the group for editing before using the line tool. You just have to draw a single edge.


Thank you. Worked perfectly!

Sounds like you should spend the time going through the SketchUp Fundamentals at

And place fix your forum profile. SketchUp Pro 5 hasn’'t been available for more than 15 years.

I could not find the area to change which version I use in my profile. I see where it states what version but not the option to change.

Click on your avatar at the top right of the forum page. Then click on the person icon at the bottom of the column and then Preferences.
Screenshot - 12_5_2023 , 1_53_49 PM

Go to your profile, scroll down and fill in the correct info. Click Save at the bottom of the page.
Screenshot - 12_5_2023 , 1_54_24 PM

I see… Change made