I have a possible workaround to the lines problem. In SketchUp you can select the side of the house and right-click Make Unique Texture. Then right-click Texture/Edit Texture Image, in Photoshop (or anything else that can do layers). Make a new layer that is empty behind the initial layer, and magic wand pick up the white parts of the image. A tolerance of about 40 should be enough to grab the full white areas. Delete, so that the transparent layer shows through. Merge layers, and try doing a save.
If you’re lucky, that will save back into SketchUp, but for me it insisted on saving a new file. Save it as PNG, and then load that file back into the texture in SketchUp. You can now fill in all of the holes in the side of the house. Where you fill in will reveal the transparent parts of the texture, so it will end up looking the same.
In Blender you will now not see any of those extra lines, but, you may get opaque black holes. To fix that go into shading, and connect the alpha nodes together. Here’s how that then looks, and how the house rendered.
