We just added a porch to our house. Porch has a 3/12 metal roof, which buts up to 11/12 shingled roof. When I first went into attic after the porch roof went on, I was astounded to discover that I could see into our front yard through the gap between the 2 roof systems (see photo
The metal installers should have turned up the end of the metal panel where it meets the shingled roof. You are correct in thinking that wind driven rain will easily be pushed uphill and into the attic space when it’s windy enough. At this point, foam closure strips (specific to this brand of metal panel) could be installed at that end to help stop water/pests. Or… You could have some of the roofing shingles removed, the metal panel ends exposed and modified for a turn up, have transition metal installed across the roof, then the shingles re-installed. This should work but would love to see pics from outside.
The deck looks like it’s 1/4".
FWIW, decking is 0.410 in, which is 13/32" MOL.
Photo of exterior is attached.
I’m not a roofer, but in looking at this some more, I’m thinking we ought to caulk the gap where I can see out into the yard (which is the where lowest part of the metal roofing hits the “boxed” part adjacent to the house)? However, I’m not sure what to do about the gaps between the shingles and the “boxed” part of the metal roof–it looks like water could easily get in those gaps.
Any suggestions would be greatly appreciated.