Summon Monster and Line of Sight / Effect

[Tarondor]

Do the Summon Monster spells require either line of sight or line of effect?

Can a caster summon a monster onto a roof if he can't see the roof? What about the other side of a brick wall?

[Stubs McKenzie]

You have to have line of sight to the location you are casting, which is chosen when the spell actually goes off, not at the beginning of casting. As another recent poster asked, if you start to cast SM into a room through an open doorway, and within that round someone else closes the door, what happens to the spell? does it still cast into the room?
The answer was no, because you choose placement upon spell completion. The rules are the same for the top of a roof you cant see, or behind a once open door, if you cant see the square, you can't cast into it. If the spell you are casting would allow it, something could be summoned into the nearest 5ft square above the roof, at which time the summoned creature(s) would fall to the rooftop, and take damage, but in any spell that this might work on, I believe there is something written to the effect that you can't summon something into an area that wont support them.

[The Black Bard]

Actually, since summon monster is not an effect with the "Target" descriptor, like Slow or Maze, you don't need Line of Sight. You do, however, need line of effect.

Example: You can cast the spell in darkness, or while blind. Line of sight not needed. You can not summon a creature on the other side of a wall. Line of effect needed.

Answers to OPs example scenarios:

Onto a roof: Maybe. If you were outside and could see the edge of the roof, you could summon a creature onto that edge, even if you could not see the entire roof. If you were inside the building, then no, you could not, although a summoned creature with a climb speed and an open window could get to the roof well enough.

Other side of a wall: Maybe, unlikely. If the wall is solid, no. If the wall has an open window, with no barriers, yes. If the wall has a window with a barrier, like glass, then no.

Final Note: Many DMs may houserule the effects of "glass" on line of effect. While I wish Paizo had put tags of [LoS] and [LoE] into the spell descriptions to clear up the mess, I must admit removing glass as an obstacle to Line of Effect generally favors monsters more than PCs. The best example I can give is Vampires and their dominate gaze. If that can work through windows (a clear violation of the concept of the saftey of a home's threshold) they become very powerful.

Just something to consider.