How can I prevent wasps from making their nests on my apartment building?

Question:I keep finding wasp nests under the window sills and any type of overhang on my apartment building. I spray them down at night with the hose, but after a few days they are back! Remember, I live in an apartment so I can't make structural changes.

Answers:
a little trick i learned from some of my friends is: where the easement comes out on the bottom of it paint it a light blue (sky blue) the wasp are stupid and they think that it is the sky so they won't build the nest. however anywhere else that isn't blue they will still build them. but thats all i have for you.