/diy/ - Do It Yourself

Wasn't sure about making my own thread about it and this is gonna make me sound like a complete fucking retard that has no idea what they're doing so it probably fits.
I'm attempting to build essentially a mobile screened in porch.
It sounds kinda stupid but it's what I'm trying to make but I'm stumped on how to put a roof on it.
The trailer it's on has a bed that's 6.6 x 18 feet and I currently have the walls built up 4.6 feet tall and was trying to figure out how to put a roof on it while keeping everything else essentially just screened in.
Any idea?