My girlfriend and I are considering buying a flat, but when we viewed it last we could hear the lady upstairs walking around, and it didn't seem like she was making noise on purpose. While I don't mind too much about this I do wonder if when I hook up my surround sound system I'm going to get complaints! I don't want to annoy people so I'm considering sound-proofing, which of course I need to factor into the price of the flat. I found a couple of pages (same company, different url... kinda iffy!) Sound proofing a wall and sound proofing a party wall How to soundproof a ceiling So the question is: how much money will it take to sound-proof the ceiling of "my flat" (812sqft) -- or just the living room (106.5sqft). Thanks for any helpful/insightful comments, I'm really interested in people's experience even without monetary estimates!