I have a ranch house with low slope roof, the first row of shingles at different spots are not laying perfectly flat and leaves a small low spot in shingle and water does not run off into gutter, instead it seeps under adjoining shingles and runs down roof overhang eave, sometimes with heavy rain it will leak into top of window, what would be the best way to correct this problem,any suggestions would be great, thanks. Paul
It could be several things causing that situation.
Bottom edge of plywood is lower than the top edge of the fascia board, which may be dipping between the rafter spans from decking deflection or it may be delaminating losing its structural stability.
The metal gutter apron drip edge may not be the correct style, where they used T-Drip ODE 90* bent material instead of the angle tru Gutter Apron Drip Edge material, which would force the bottom edge of the lowest course of shingles to raise up.
It could be poor nailing of the metal drip edge also.
If it is causing leaks, it is time to get those shingles removed and inspect the decking and fascia boards before further damage and rot begins to occurr.
Ranch style homes change the pitch from the gable to the porch. If the pitch is below specs, it might not be something you can fix, without tearing off. If it is a short deck or high fascia problem, here’s some ideas.
I think ed’s on the right track.
High fascia: tear off first 3 or 4 rows and install a linear starter course. I would look at something like a peel and stick, at least 24" wide all the length, sealing the laps. Then install the shingles, placing the fasteners at the very top of the shingle to cut down on the chance of the water corroding the fastener.
Short deck: tear off first 3 or 4 rows and install a 12" galv roll of valley over the gap, all the way down, sealing the laps. Just trying to keep the shingle from cupping again.
It’s aggravating when someone could have done it right the first time, so easy. Most problems I run across, are generally laziness. Just not doing it the proper way, because they didn’t want to buy what they needed.