I’m not sure I understand your question but I’m guessing you want to divide the face into two separate regions by adding that edge. Is that right? The new edge must intersect the edges at the top and bottom of the face in order to divide it. It’s hard to tell what you are showing in the screen shot but it looks like you haven’t divided it.
Upload the SKP file so we can see what you have going on and help you identify the exact problem.
Sometimes things go buggy and faces don’t divide properly. Like, you have an edge that slices a face in two but there’s still one face. Usually you should select the big face, remove it and try to create faces again by redrawing one of their edges.
Sometimes faces may overlap. ThomThom’s CleanUp plugin may help you clean such mess.
House.skp (155.5 KB)
I’m trying to connect the top of the line to the face’s edge to make a strip-like area like the ones to the left. But Sketchup doesn’t count that strip as it’s own area when I do it.
The clue that your edge doesn’t divide the face is it is shown as a thick profile edge. If you zoom in closely, you can see that the edge terminates at a guide point which is not on the bottom edge of the wall.
Here I’ve moved the guide point down on the bottom edge and redrawn the vertical edge. It now divides the face and is shown as a normal edge, not a profile edge and the surface is now divided.
Turn on edge color display as “By Axis” (marked red) and see that not all of your edges are aligned to world axes. For example, all vertical lines are blue, so some of them are not vertical. Also, I guess you intended to draw the bottom lines along red and green axes. If so, note that they also should be marked respectedly with red and green color, but they aren’t.
That’s by the way.
Linen, see this plugin: https://extensions.sketchup.com/en/content/edge-tools²
If you don’t use it, give it a try. The first tool in the toolbar will make this work a lot faster. You won’t have to draw manually each vertical edge.
Plus it guarantees every edge will lay properly on face and the face will be split as it should.
Here’s an option for drawing the wall with the geometry using only basic native tools.
I drew the gable end without the roof and pulled the bottom of it down a little bit. Then I drew the center batten as a rectangle on the surface. Notice that the bottom of the batten does not come all the way down to the bottom of the face.
This is good practice learning how to create geometry in SketchUp but unless you have some real need for this to be drawn as 3D geometry, a texture would be easier and would create less overhead.