That s a simple low cost solution that can tie in well with the main house.
New addition roof ridge framing to existing roof.
When a shed roof ties into an existing roof the new roof could be a simple lean to that covers a deck or porch or it could be the shed roof of a substantial addition.
Bed the end of each shingle in a 2 in wide ribbon of roofing cement placed 4 in.
Then mount new trusses on the new addition walls.
Tying in to an existing gable roof.
How to tie a additions roof to existing roof roof designs to attach to existing home how to construct a roof from an exsisting shead how to attach a deck roof to existing roof how to add a roof over porch cost to tie into existing roof attache porch roof on house attach shed roof to house adding a roof to screened in porch adding a roof to existing.
Shingle the addition roof letting the new shingles fold through the valley center and onto the old roof deck by at least 1 ft.
Up from the valley center.
Re lay the shingles you removed from the existing roof.
In any case the structure.
Cut two rafters with a circular saw to the pitch of the addition roof and nail them across the rafters on the old roof.
Framing addition matching existing roof plane not sure i understand completely but from the 3d sketches it looks like you are lowering the pitch of the roof over the area where the addition is put to account for the greater width.
After installing the rafters we still had to extend the porch roof back over the shed roof creating a valley on either side.
Tie into the end of an existing gable roof by removing existing facing boards wall siding and any other obstructions back to the first truss of the old roof.
They form an upside down v with the point at the top of the addition roof.