The short answer
A leak that only appears during heavy or wind-driven rain usually means water is getting past a detail that handles normal rain but is overwhelmed by volume or pushed sideways by wind. Common culprits are flashing, valleys, gutters backing up, and wind-driven rain entering at the eaves or under siding above the roof line.
What causes it
| Cause | How you can tell | How common |
|---|---|---|
| Wind-driven rain at flashing | Leak only when rain comes from one direction | Very common |
| Overwhelmed or clogged valley | Leak during downpours, valley holds debris | Fixable |
| Gutter overflow backing up under shingles | Water at the eave, worst in heavy rain | Gutter problem |
| Undersized or clogged downspouts | Overflow at a specific corner | Drainage |
| Siding or stucco above a roof line | Leak at a wall-to-roof junction | Often not the roof |
| Low-slope section at the limit of the shingle | Only leaks in volume | Needs a different system |
How fast do you need to act
Not an emergency, but it will get worse, and because it is intermittent it tends to go unfixed for years while the decking underneath quietly rots.
What to do right now
- Note which direction the wind was coming from when it leaked
- Check gutters and valleys for debris after the next storm
- Look at any wall, chimney or siding that sits above the leak point
- Run a hose test with someone watching inside, working uphill in sections
- Have the roofer check kick-out flashing where a roof meets a wall, which is a classic missing detail
What we see in the Hill Country
Missing kick-out flashing where a roof edge meets a wall is one of the more common defects we find on Hill Country builds from the 2000s. It leaks only when rain is heavy enough to run down that wall in volume, which is why it hides for years and then shows up as rotted sheathing behind the siding.
When to call us
We inspect for this at no charge across Boerne, San Antonio, New Braunfels, Kerrville, Fair Oaks Ranch, Bulverde, Helotes, Spring Branch, Austin and Stone Oak. You get photographs of what we find and a written explanation, including when the honest answer is that nothing needs doing yet. Call (210) 245-4125 or book an inspection.
