This should cover the most leak prone areas.
Repair where two roofs meet.
Cut each side at the upper end of the valley to conform with the corresponding slopes of the roof.
Apply a generous layer of roof cement over the repaired tear then set the patch over the cement covered area.
If leaks continue to occur from ice dams consider installing roof edge heating cables.
This should cover the most leak prone areas.
Sealing metal roof valleys watertight fix valleys where two rooflines meet are typical problem areas on metal roofs.
Cover the repaired area with a patch of roll roofing.
The valley flashing laid over the joint where the two roofs meet should overlap the step flashing at least 2 in.
Slide the right edge of the flashing under the highest roof pitch.
Position the flashing between the two roof pitches.
If leaks continue to occur from ice dams consider installing roof edge heating cables.
Place the 2 by 4 inch piece of lumber along the center of the flashing.
Attach the valley in place with 1 1 4 inch roofing nails and a shingle hatchet or hammer.
A 2 12 pitch should actually get a rubber covering as shingles will not.
If you didn t need to replace the roof substrate cut a patch of tar paper or rubber roll roofing 12 in 30 cm wider and longer than the mended section.
My suggestion is to tin the junction of the two roofs and put two rows of water and ice barrier down as added protection.
We mitered the two subfascias where they met and then filled in with wedged shaped blocking screwed to the tops of the common rafters to support the plane of the shed roof.
Then reshingle sliding metal step flashing behind the fascia board the trim behind the gutter.
Using 3 layers of thermal tec s mr multi ply roof system where most of the movement occurs will provide a watertight seal in these areas.
Make sure that all of the procedures preceding roof flashing are done so that you can flash the roof.
Then reshingle sliding metal step flashing behind the fascia board the trim behind the gutter.
Step 2 consider your available flashing options.
Step 3 calculate needed flashing.
Step 1 make sure all your homework is done.
We cut the rafters to length on the porch roof so that the subfascia would be in line with the subfascia on the new overhangs we d added to the shed roof.