The next step after creating walls in a 3d architectural model is to cut holes for doors and windows. We demonstrate the process in our SketchUp courses.
First make sure that the the Floorplan layer is visible – this will show us the locations for our doors and windows. However, these locations are hard to see when working in a solid display mode. So go to Window > Styles, and choose the Default Styles section. Here we have an X-ray mode, the last style in the PC version of SketchUp – it’s further up in the Mac version.
Now zoom into the front door location. It’s very important to double-click on the External walls group to enter the group. Note that your guides will disappear, so change the style to Wireframe mode. Now you can see the Floorplan lines.
There are several methods of creating the guides for the doors and windows. One is to use the Tape Measure tool (or hit T on your keyboard) to create two guides the height of the door, for example 2050 high. To do this click & drag upwards from the base in the Blue direction. Note the length on the bottom right of your screen > and punch in 2050 > Enter. Then use the Rectangle tool (R) to create the door outline.
Alternatively you could just use the Line tool to create each line, or click on the two door base points with the Rectangle tool and pull upwards, then type in the height. Any method is viable – in the end each user finds a few techniques which work best for them.
Now we switch to the X-Ray style, or any of the solid styles. Use the Push/Pull tool (P) to push through the wall till the Offset Limit (or On Face) message appears > and click to delete the face. It’s always a good idea to orbit upwards to see that the doorway has been cut through – if it didn’t work, you may not be inside the walls group. Lastly use the Eraser tool (E) to erase the guides. The same method is used to cut out the windows.
Many useful tips and techniques can be found at the SketchUp website. And see many examples of our own clients’ work on our Facebook page.
Other related SketchUp Blog Posts:

• SketchUp background
• SketchUp introduction
• SketchUp modeling
• SketchUp contours
• SketchUp workspace