Still printing Job Smolders' birdhouse - a thing of beauty (goed gedaan Job!) - and experienced that the roof elements need a lot of support and once printed also do not come out 'clean' due to the printing orientation.
Job's creation can be found here: https://www.thingiverse.com/thing:2852328
Hence I made some built in supports such that the roof elements can be printed vertical. It not only prints cleaner, but also faster. Just break off the supports after printing.
I recommend to print with 3 perimeters and 10% infill. Despite the supports, still make sure you have a good 1st layer adhesion.