I've seen a couple of "roofs" in maps. Some divide it just by a line, others by a "y" shape, and others by a X.

Any tips on what im suppose to use?
Like, line for long houses, X for small, etc?

Ex:
https://s-media-cache-ak0.pinimg.com...46a1decac7.jpg
http://irontavern.com/wp-content/upl..._1400x1080.png


Thanks!