I'd like to build a screened in porch on an existing concrete slab in my back yard.  Here is a picture:  http://sphotos-a.xx.fbcdn.net/hphotos-ash4/s480x480/318778_10101127044325993_1168315941_n.jpg

 

Notice the addition on the right side of the picture.  If it weren't for the addition I'd build it with a normal triangle shaped roof like this:  /\.  Because the roof will butt against the side of the existing house as well as the roof of the addition, I'm not really sure how to go about this.  Any suggestions?