Mastering the eraser tool/push pull for shaping geometry


I am new to Sketchup, but having a good success of creating house design the last couple of months.

However, i find it hard to really master the eraser tool/push pull tool for shaping geometry.

I have tried to set up an example in the picture in the link below:

I want to create a sloped roof, and i want the walls to flush with the surface. I am trying to draw the shape with the line tool in the vertical plane, and use push pull to remove the geometry. It leaves me with the remaining lines as seen on the picture. If i try to erase them the entire wall surface disappears. If i try to hide them erase + option, then there is still a slight remaining thin gray line left. If i try to go to Edit -> unhide all, then the lines are clear again. I can of course lift the surface of the roof a couple of mm to avoid the line… but hey, it seems like a workaround, which i would try to avoid so i can continue with exact measures

I have watched many tutorials and searched this forum. Maybe you have som hints?



Instead of drawing the lines on top of the roof draw them on the bottom. Also I would highly suggest looking into groups and components.

if you make the roof and walls separate groups it will be much easier to edit.


Thanks, it is a good idea to draw the “markup” lines on the bottom. The roof os grouped in the example i show there. All at layer0


Its also helpful to use the “Hide Rest of Model” option when you are making edits like the ones above. Check it out.


I’m curious about the hidden lines still showing up faint grey for you. That should not be the case unless you have show hidden geometry checked. If a line is hidden it should not show up at all, so I wonder whats going on there.

As in the real world, I would consider making your walls end on the bottom side of the roof, instead of piercing through the roof to the top surface.

Getting used to working with groups and components and editing within them can be slow and frustrating at first but it’s the only way to truly progress in sketchup. Keep at it.


The grey lines aren’t from the hidden edges, these are indeed invisible when hiding them. What @achtomas is seeing is the wall face at certain viewing angles since they still “collide” with the roof face as a faint grey line. There need to be some distance between end of wall face and top roof face. In fact it needs to end at the roof bottom face, as in real life and as mentioned above by others.


Ahhhh Thanks @Wo3Dan. Z-fighting between the top edge of the vert and the horizontal planes is what he’s seeing. Of course… Linear Z-Fighting? Edge-Fighting?


That’s a good description.