Place the rib inside closure inside the groove both overhangs will have this.
How to fit lean to roof.
Step 1 make a ledger board to fasten to the existing wall and support the upper end of the lean to roof.
Cut out a notch on the top of your posts as shown in the image above.
Use a 2 by 4 inch board for a short roof up to about 8 feet a 2 by 6 for a longer one.
Place the starting panel onto one edge of the roof.
The side of the panel that has a slightly flat side is to place on the roof.
Measure the width of the outside wall and cut the board with a circular saw to the same length.
Next place the supporting posts into the notches.
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 it ties into the framing of.
I cut rafters out of 2x8s frame this pole barn lean to.