I have added some extra files to the dropbox.
LVL2 got extra doors and windows, in case you want to cut them out from the walls and add your own doors and windows to open.
LVL3 got the above and also some extra roof top details. With these you can pimp your roof if you like the extra detail.
Print these on heavy cardboard and cut out. Don't forget to color the edges!

Then you cut the long bars into the desired length.

Glue these onto the wood base part. When you make two of these you can put them on your roof. To make the final long bar, prepare one or two of the single bars. I made two so I can make them even thicker.

Then glue the prepared parts onto the roof and finally glue the long bar in position!

You can do the same with the alternate roof top details. There you just cut out long bars and glue them on horizontally.
I like to double up details like this and give the model more depth and detail. If you are taking the "fold-flat" route, you can still glue the doubled up parts to the roof but leave the top long bar unglued. You'll have to lay that in position once the roof is fold-assembled.
Hope you enjoyed this. As always,
happy building!
Chris