The top plate on each side will overlap and attach to one adjoining wall corner.
How to attach a shed roof to an existing wall.
This will occur at all four corners adding an additional attachment point for each corner.
On a two story house you can usually tie the ledger into a band joist also called a rim joist located between the floors as shown below.
Read on to find out how to attach a patio roof to an existing house.
Staple on roofing paper and shingle the new shed roof starting at the bottom and working up.
Repeat for the remaining two walls.
Add decking atop the roof and nail on metal flashing where the shed roof joins the existing roof.
The most common roof to wall intersections involve either a gable roof with its ridge running perpendicular to the wall or a shed roof that slopes downward away from the wall.
In the case of a lean to roof over an addition the existing rafters will have to be cut away to accommodate the addition and the shed roof will require support where.
Prevent the splash of the rain let the air flow.
Add a second top plate to more securely attach the walls and to add strength and support for the roof.
After that you can seal the brackets from the front.
Attaching below the ridge.
Reinstall the removed shingles or use new shingles to cover the area of the old roof which was exposed.