Hello,
I want to put a screen in porch with a shed roof on the back of my house. Plan is for a 4/12 pitch.  Because of the layout of the house, I want to attach the back of the roof to the house several feet above the second story floor. 
I wonder if you are allowed to attach the board to which the rafters attach onto the second story wall 2x4s or must that board attach to the joist board for the second story floor. I cannot do the latter.

Hello Ivanhyde,
Thank you for sharing your question!  We have put together a short response and linked an accompanying youtube video which we hope will help answer your question.  We also recommend consulting a structural engineer for further clarifications if needed.   

Response:
When attaching a ledger board where there is no rim beam certain precautions need to be taken.  First, you need to install a lateral tensioner to keep the ledger and rafters from pulling away from the building.  Second, you need to make sure there is blocking installed between the joists, or you can see if you can install a rim joist to fit flush with ext. of sheathing.  Your ledger will be anchored by the Lateral Tensioner and then screwed into the blocking.  You will need to make sure the vapor barrier is replaced and secure and all moisture has the ability to run out and away from the surface. 

Video to help explain here:  https://youtu.be/9INlIOOVSpY?si=6UdOxFrhkPIhuuuQ

(The Lateral Tensioner they used in the video is:  Simpson DTT2Z)