Laura,

I had another, more detailed look at your design, and there's a few remarks I would like to make.

1 - When designing a house with a second floor, you may want to read the manual on that topic. (PDF) It will make life a lot easier. Now there are lamps burried beneath the floors (aplique dormis), boxes to elevate floors, etc.
2 - Make your file smaller: change textures on the balcony railing (barandilla), the windows and doors to a brownish colour. It will reduce file size and make rendering faster.
3 - The texture on the balcony floor renders as black. Maybe you deleted the image file from its directory, or moved it to another place, so SH3D can't find it. More specific: the large black spots are caused by the objects called escalon and deck. Regardless of colour or texture, they are always black. Delete them and use a simple box to simulate the elevated floor.
4 - The small black spots appear especially in the highest quality setting, but I'm not sure (yet) what causes them.

Hans