I used to go through the exact same thing when I lived with my folks. He'd be downstairs, up really late, watching TV, and I was upstairs waiting and waiting for him to go to to goddamn sleep. :p
Sometimes I thought I could get away with puffing out my bedroom window, but their room was also upstairs, right accross from mine, so a lot of the time, he would come up and he could smell it. He'd bang on my door yelling, "Take it outside boy!"
Then I moved into the basement and smoking it was ni problem. I'd have to do it out my window mind you, and sometimes I'd have to be careful if they went outside. If that happened. I just toked in the shower, turned on the exaust fan and blew the smoke out there.