Cutting holes into walls through CAD?


Hoping someone can help here. I have a simple solid wall 300mm deep with perfect geometry. Over the top of that wall I have laid a flat 2D CAD drawing (elevation) which I would like to snap to as I punch holes in for the windows. However When I try to do that it just draws a new face as a separate object rather than cut in to the face of the wall behind. When I hover over one of the corners of the CAD window it says its outside the active area but the CAD is flat on the face - I’ve double checked this. I can cut a rectangle no problem into the wall but just not using the CAD to snap to. I thought Sketchup was more intelligent than this and would recognise I was wanting to cut a face. I know the CAD is completely flat. Any Ideas?



This has probably got a simple fix but exactly what it is depends on the way the model is made. Can you share the SKP file so we can give you the correct answer without guessing?


Thanks Dave Hopefully this dropbox works. Try cutting in this last window. Ive already done the rest the long way around by resizing a smaller hole outwards.


…obviously I enter the group to cut first.


The problem is that the lines for the windows are not on the surface of the wall. It’s close but not close enough. The Line or Rectangle tool winds up snapping to the lines in the window outline instead of on the face of the wall. The wall of the box isn’t on axis, either so the plane of the wall and the plane of the imported lines aren’t parallel.

You could move the lines back to the wall which would help.

It seems like kind of an odd and difficult way to create the model. What is your end goal with this?


Thanks Dave you are right its ever so slightly not square. The CAD was supplied and I would usually work up from the plans with the rectangle tool so I know everything is square but I was advised the Plans were wrong in the drawing so I extruded the shape from the side elevation. Something must have got twisted fractionally. It is sub 1mm along the whole length as I cant measure the difference. I would usually type in 90 degrees when rotating so Ii must have got sloppy.

With regards to model creation what do you mean by a difficult way to create the model? Cheers


I understand more what you were starting with now.

I guess I would have converted the imported line drawing to have faces and used it for creating the 3D model. Or I would have set it up in the background to use as a reference for drawing the 3D model. I guess it’s just a different way of working. Do you have other elevations and a plan, too?

You say the plans were wrong? Did they tell you what was wrong?

As for the sub-millimeter error, you can see it if you increase the precision for the model in Window>Model Info>Units.


I see. Yes I have plans and eles. I usually extrude from the plans, but just tracing over a locked group then align the elevations on the faces and punch through.

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