Hollywood Reporter has a Q&A with Charlie, in which he talks about Synecdoche, not writing for people, burning houses, and dreams.

THR: It has many surreal elements to it. Were there dreams you were having that inspired you?

Kaufman: I'm interested in the structure and logic of dreams as a type of storytelling -- dream logic and images in a non-dream story. It wasn't about my dreams -- it was about the visceral, emotional feeling one gets in them, the idea you can have things happen that are irrational and they just seem perfectly natural. That's a hard thing to translate into a story outside a dream. I was interested in not explaining things, having them just be poetic.