Yesterday I have built a new model of the house without the joining wall. Usually there is just the step from the dirt ground to the raised tatami area.

I have also cut out some shoji doors and glued them in an open position. As this is a glued assembly, I modded parts of the joining walls to form these upper ceiling parts. For the fold-flat version we will have to skip these, they wouldn't hold as there is not much space to make them connect. But The roof will hold on its own due to the angle forming parts.

And above is a view from the "street" side and below from the "garden" side.

Time to make the instructions! :-)
Happy building,
Chris