Ceil

I need some help. I'm working on the "All Around the Neighborhood" quilt from the fabshophop and am having trouble trying to make the roof of the house.
It seems there must be some kind of trick or some knowledge I don't have but I can't seem to be able to figure out how to sew on the upper triangle so that when the time comes to sew this block to another, the top of the roof (the tip) won't be cut off.
I know I have to have 1/4 inch above the tip but I don't know how to line up the two blocks to achieve that. And maybe this one will be fine, but when I go to line up the next triangle, I can't figure out how to get them together so that there will be that 1/4 inch seam at the top. I would also appreciate it if someone could tell me what this is called as my attempts at searching for help online haven't given me any results that would help here. Thank you.