Not sure if this one really helps you much because.........................IT WORKED PERFECTLY!
But I thought it would be nice to get a (hopefully reasonably well modelled) example out there that worked perfectly.
The house is far from finished. This one is just a slab, outside wall and the inside walls.
However some of the good points
1) I used the same sketch for the Pad for the floor slab and the external wall so there is only one sketch to adjust the overall size of the house
2) The floor slab is reverse padded so that my global origin is the top left ((right from within the house)) front of the slab
3) all the interior wall worked PERFECTLY from one sketch, and everything in that sketch is reference from a construction line on edge of the slab at the opposite end from my global origin
4) the point about 3) is that when you change the overall length of the house in it shortens/lengthens the open plan living area leaving all the bedrooms etc. intact. Also if you change the width of the house all the ends of the interior walls retain their position relative to the outside walls.
5) so within a reasonable range you can simply change one parameter in one sketch and the house will redraw to the new width/length.
Now that's got to be good for a general plan for say a building company who want to sell modified standard designs.
So anyway I thought I would have a little celebration and send you this file while it is still perfect, has no bugs etc.!
Now I will go and add a whole lot more detail ...and see if I can't find some more bugs.
Just in case you haven't noticed...I'm really liking your Arch module. And since I am drawing flash new houses, my wife is actually, finally, interested in what I am doing with FreeCAD, except now she wants me to build one...for real. Whoops..me and my big mouth!