Install a pre-formed foam filler between the roof sheet and the gutter flashing at the gutter edge of the roof. This will serve as a physical barrier against water. To prevent water infiltration into the building, install a profile filler at the highest places under a ridge cap or apron flashing. This will help to block off any holes in the roof sheathing where moisture may be able to penetrate.
If you want to go further than this, then consider installing a rain screen. These can be installed as part of the original construction or as a replacement item. They work by preventing large drops of water from entering the house through the roof while allowing smaller droplets to pass through. This allows small amounts of water to drain away rather than puddle on the floor inside your home.
The final thing you should consider is the source of the water issue in the first place. If your gutters are clogged up, there will be no escape for excess water. It will simply run down the front of your house and into the ground or next-door neighbor's yard. You need to call in a professional to clean out your gutters once a year or so to ensure that all of the debris has been removed and that there are no obstructions preventing water from flowing freely.
Overall, keeping your house dry requires careful planning. You need to understand how water gets into your home in the first place so that you can take steps to prevent it.
I believe the water is entering through a hole through which a pin or large screw is inserted to hold that section of the roof in place. As a first try, I'm thinking about climbing a stepladder, then putting some of that expanding gunge stuff through/around the hole and hoping it blocks the water from getting in. Any other ideas?
Here's the setup: Two-car garage with insulated ceiling and floor. The roof is asphalt shingles. There are no leaks anywhere else on the house. We've had heavy rain recently but not enough to cause this problem.
The hole in the roof is about 1 foot by 2 feet. It's near the top of the garage roof where there's a very small section without any insulation. There's a metal beam underneath that area of the roof but it doesn't reach all the way to the ground.
I checked around the edge of the hole and didn't see anything dripping into an underground pool. The only thing I could think of was that maybe there's a leak somewhere nearby that's causing water to seep under the edge of the roof into that spot. But since we've had so much rain lately I figured there might be something else going on here too.
Loudspeaker system If you have an overhanging roof, consider installing a louver system. The divots in these metal sheets catch water and guide it away from your property. Attach them directly to your house's siding, just beneath your roof, and watch as raindrops are forced out and away from your foundation. Louvers come in a variety of sizes and shapes; they're available for almost any home exterior decorating style including traditional, contemporary, and shingle.
Installing a louver system is easy. First, measure the distance between your roof's edge above ground level (AGL) and its opposite side. This is the maximum width of your louver panel. Next, find a location on your house where there is enough space for this measurement. Finally, install sheetmetal screws into the wood siding at evenly spaced intervals to hold the louvers in place. You can purchase screw kits with each set of screws being a different length so they can be installed with one hammer blow. When putting up the louvers, make sure they aren't blocking your attic access or vent pipes. Also, take care not to damage any part of your house when mounting the louver panels to the siding.
Louver systems are very efficient at preventing water from damaging your house. This method is recommended for homes with asphalt or concrete roofs that don't have gutters. It's also useful if you live in an area that experiences heavy rainfall.