I can't seem to find a way to use obstacles to shelter from dragon breath attacks. Trees are useless. I'm at Winterhold in the entranceway to the courtyard seemingly protected from both sides and above but the icedragon's icespikes keep killing me even when I can't even see the dragon through the stonework. Is architecture pervious to breath attacks just like it lets rain through? I might try going in and out of the load door to the school if the damn dragon would stay put and not keep flying out of reach. I don't know why a tiny shield would protect you but a stone wall doesn't.

only certain things protect you. You have to be behind a solid stone wall, AND not right next to it.

Ward spells?

Become Ethereal is also useful.