Here's an example of how walls have been built. If you look closely on original pictures you can also see 2 x 2 top hinge piece (marked in Yellow here) used for attaching it on the bottom.
Roof is, however, not connected to the top edge. This is how top edge looks on one side of the roof as it is made out of Technic pieces, mostly:
4623a or ...
The slats seem to be 1x4 tiles on a base of overlapping 2x4 plates. It's easier to see from the inside.
The roof T-pieces are 32013 Technic, Axle and Pin Connector Angled #1 resting on a 4623b Plate, Modified 1 x 2 with Bar Arm Up (Horizontal Arm 5mm).
Are those the pieces you're looking for?