As always - if you intend to paint the model, you should paint all of the parts BEFORE assembly. It's much easier that way.
First locate the parts of the front wall:
Glue the two halves together and then glue the decorative trim pieces as shown (they help to reinforce the the join between the two halves):
Glue the header over the doorway as shown:
Repeat for the other end wall (which is in one piece):
Glue the end walls to the side walls as shown - use something you know to be square to ensure that the ends and sides are at right angles - set aside for the glue to completely set:
NOTE: Take extra care when separating out the curved A frame parts - they are quite fragile until assembled into the complete structure!
Locate the parts of one end wall:
Glue together as shown - and set aside on a flat surface while the glue sets:
Repeat for the other end (only one end has the doubled-up "legs"):
Locate the larger and smaller roof beams and all of the remaining curved roof parts:
Being careful to apply glue to ALL of the contacting surfaces, glue a curved roof joist to each of the slots in the two roof beams:
Push them all in as tightly as they will go and set aside onto a flat surface for the glue to set. Repeat for the other side of the roof:
Next, locate the roof apex beam:
Glue into the slots on one side of the roof frame:
Then glue the two cross members to the lower beam:
Now glue the two halves of the roof together. Take the time to check that every one of the parts is pushed tightly together - both along the ridge line and where they fit together in the main structure:
Glue one of the A frames to each end of the roof structure. Leave the roof in this position until the glue has started to harden...
Then flip it right-way up and drop it into the building walls so it'll finally dry in a way that fits nicely. DO NOT glue the roof to the walls.
Glue the decorative ridge piece in place:
Glue the thin cross-members in place into the remaining slots:
Glue the decorative 'horns' in place into the slots in the end walls:
We're all done with the wood parts:
Finally, remove the roof structure and trim the roof material to fit with a small overhang at each end and over the sides. When gluing the roof material in place, be sure to put plenty of glue on all of the beams and joists that contact it so you get a firm join everywhere.