Your shed walls are going to attach in two main ways.
How to attach shed roof to walls.
If attaching a patio roof to a ledger beneath the eaves does not allow for enough headroom you can set the new patio roof s rafters on the wall s top plate.
When securing your walls to the floor you will nail or screw through the bottom plate of your wall and directly into the floor joists.
Fit rafter board into the u shaped hangers and nail it in place.
Add decking atop the roof and nail on metal flashing where the shed roof joins the existing roof.
Frame a wide doorway by bracing the shed roof temporarily and cutting studs with a reciprocal saw.
Install shed rafters from the ledger board to the outer wall using metal rafter hangers which attach to the ledger board with screws or nails.
Nail a 2 by 6 inch header board between studs over that doorway and secure it with studs from the header to the floor.
Toenail a truss into the top of the wall plate by nailing through the sides of the bottom chord at a 30 degree angle.
Seal the top with clear caulk.
Attach roofing to the garage wall with bent metal flashing that goes up the wall and over the roof.
The best method is to snap chalk lines on the shed floor to outline the truss parts.
Leave this doorway open.
They will be fastened to the floor and they will be attached to each other.
Then use the chalk lines as a guide for cutting the truss patterns and assembling the trusses.
When a shed roof intersects a wall a ledger board attached to the wall serves as a nailing surface for the ends of the rafters at their upper ends.
The ledger board in this case is essentially.
If you re building your own roof trusses the handiest place to assemble them is right on the shed floor.
How to tie a additions roof to existing roof roof additions to existing roofs how to construct a roof from an exsisting shead how to change a roof line how to attach a deck roof to existing roof how to add a roof over porch attache porch roof on house attach shed roof to house adding a roof to screened in porch adding a roof to existing.
But you have to do it before you build the walls.
Build a real addition by removing the siding from the shed and building new walls.