Here is my plan for the first floor.
I will look at how to add a roof, but what I quickly saw yesterday is that it is not that easy.

Adding a roof/ceiling is not really that hard. How hard depends a bit on your need for accuracy in terms of roof/wall thickness. If measurements of walls/roof do not have to be 100% accurate, you can use one of the roof models from the free 3D models page, in Sourceforge or elsewere. Just scale a sloping model and a flat model, and you should have a basic ceiling/roof.

If, however, you need the measurements to be just right, you should create your own. If you read the sloping ceiling guide in the blog (just forget about the window if you do not need it), it should not take you very long to get it right. Good luck.

ok

PS - BTW - creating a custom roof with modelling software or the Generate 3D shape plugin , is also relatively easy, but probably a bit more work (learning) than with just the approaches mentioned above.