Some roofs only leak when there is a rainstorm. Leaks that only occur when there’s a storm are often challenging to track down because at times it’s due to poor installation. In most cases, it happens when shingles are slightly loose at the joints where they meet due to a loose interlocking screw. Leaks resulting from such a situation are difficult to find, especially when the shingles appear to overlay one another as they should.
Inspect shingle joints where the screws have been installed. Gently press the points up and down continuously with your palm. Anywhere you feel the shingles are loosely fitted could be the source of the leak that is giving you a headache.
Test all loose shingle intersections with a hose to see if water drips into the attic. If it does, tighten the loose screws or replace them with new ones. Next, test the intersections again. If water doesn’t enter the attic, congratulations! You’ve just found a difficult leak to trace and repair your leaky roof.