How do area spells interact with corners and other obstacles/covers?

[Red Bear]

the fireball description mentions fire spreads around corners but what about other spells and other obstacles? are there some generic rules mentioned somewhere? for example I had a druid casting thunderwave against my players and one of them in the area was behind a corner in another room with the door open and didn't think the spell should hit him. I thought that as long as there is some path without total cover the spell works.
What do you think?

[PhoenixPhyre]

the fireball description mentions fire spreads around corners but what about other spells and other obstacles? are there some generic rules mentioned somewhere? for example I had a druid casting thunderwave against my players and one of them in the area was behind a corner in another room with the door open and didn't think the spell should hit him. I thought that as long as there is some path without total cover the spell works.
What do you think?

Unless it says it spreads, it doesn't. Total cover happens when there are no *straight* lines from start point to target. So it shouldn't have worked in that case.

[Red Bear]

Unless it says it spreads, it doesn't. Total cover happens when there are no *straight* lines from start point to target. So it shouldn't have worked in that case.

Thank you for your answer