Here we have a tar and gravel roof which has been “spudded” to expose the split and enable us to apply the patch materials onto a smooth, clean and dry surface. The spudding process is mandatory for long term performance of patches.
This is an especially deep split in the roofing plies (tar felts) of a tar and gravel roof system. One doesn’t realize the degree or magnitude of the split until it is exposed through the spudding process. Regardless of the size of split it may still be difficult to find due to the hidden membrane characteristic of T&G roofs. Splits can also be concealed by organic debris that falls on the roof.
Unfortunately I’m never surprised but constantly bewildered by what I find when searching for leaks. In this case the high-water-flow area of a metal valley had a good sized hole cut into it by someone who wanted to put a vent, for bathroom fan, in that exact location. Common sense won out and the roofer was directed to put the vent somewhere else but the repair job to fix the hole was simply placing a piece of metal overtop of it and then burying that under shingles. Guess what? It leaked.