💧 Leak Source Quick Guide
- ✓ 90% of roof leaks during heavy rain come from flashing, not shingles
- ✓ Ceiling stains often appear far from the actual leak entry point
- ✓ A leak that only appears during heavy rain may indicate wind-driven rain entry
- ✓ Do not caulk over flashing — it traps water behind the repair
- ✓ Persistent leaks need professional diagnosis, not repeat patching
Savannah gets approximately 50 inches of rain per year — significantly above the national average. When that rain comes in heavy bursts, which is typical of our summer thunderstorm pattern, it can overwhelm roofing systems that appear perfectly fine during normal rainfall. If your roof leaks only during heavy rain, you have a specific type of problem that requires a specific diagnostic approach.
This guide covers the most common causes of heavy rain leaks, how to find them, and when a simple repair will fix the issue versus when the leak is a symptom of a larger problem.
Why Your Roof Only Leaks in Heavy Rain
If your roof holds up fine during light to moderate rain but leaks during downpours, the issue is usually one of these:
Flashing Failures
Flashing — the metal pieces that seal transitions between your roof and walls, chimneys, vents, and skylights — is responsible for the vast majority of heavy rain leaks. During moderate rain, water flows smoothly past flashing on its way to the gutter. During a downpour, the sheer volume of water can exceed the flashing's capacity, particularly if the flashing is corroded, improperly lapped, or has lifted seams.
Wind-Driven Rain
Savannah's storms commonly pair heavy rain with strong lateral winds. Wind-driven rain pushes water horizontally — under shingle edges, into ridge vents, and behind fascia boards. A roof that is perfectly watertight against vertical rain can leak badly when rain comes in sideways at 40+ mph.
Clogged Gutters and Downspouts
This is the most overlooked cause of "roof leaks." When gutters are clogged, water backs up over the gutter edge and flows behind the fascia board, down the wall, and into your home. It looks like a roof leak, but the roof is fine — the gutter system has failed.
Underlayment Degradation
On older roofs, the underlayment (the waterproof layer beneath the shingles) may have degraded to the point where it no longer provides a secondary water barrier. During moderate rain, the shingles handle everything. During a deluge, water gets past the shingles and finds degraded underlayment that can no longer stop it.
Finding the Leak — Inside vs Outside
One of the most frustrating aspects of roof leaks is that the water entry point on the roof surface is almost never directly above the water stain on your ceiling. Water travels along rafters, sheathing, and insulation before dripping to the ceiling, sometimes traveling 10-15 feet horizontally.
To locate the actual entry point:
- Go into the attic during or immediately after a heavy rain
- Follow the water trail upward from the wet spot — look for water tracks on rafters
- Mark the entry point with a nail pushed through the roof deck
- From the outside, locate the nail and inspect the surrounding area for the failure point
If you are not comfortable doing this yourself, our professional inspection includes thermal imaging and attic inspection to precisely locate leak entry points.
Repairs vs Replacement
Many heavy rain leaks can be fixed with targeted repairs — re-flashing a chimney, sealing a pipe boot, replacing a section of ridge vent. These repairs are typically in the $300-$800 range and can be completed in a single visit.
However, if your roof has multiple leak points, the shingles are past their expected lifespan, or the underlayment is degraded, repairs become a game of whack-a-mole. Each fix solves one leak while the next one develops nearby. At that point, a full roof replacement is the more cost-effective long-term solution.
Roof Leaking? We Find and Fix the Source.
Free leak inspection. Precise diagnosis. Lasting repairs.
Why Heavy Rain Causes Leaks in Savannah Homes
Savannah's heavy rain events — sometimes dumping 2-4 inches in a single hour during summer thunderstorms — expose roofing vulnerabilities that normal rainfall doesn't test. The sheer volume overwhelms drainage systems and creates hydrostatic pressure that forces water through even small gaps in flashing, deteriorated sealant around vents, and worn shingle seams.
The most common heavy-rain leak locations in Savannah homes are roof valleys where two slopes meet, step flashing at sidewall-to-roof transitions, and around chimney cricket diverters. These are areas where water volume concentrates and the underlying waterproofing is most critical.
Immediate Response Checklist
- Place containers under active drips and move furniture away from the wet area
- If water is pooling on the ceiling but not yet dripping, carefully puncture the center of the bulge with a screwdriver into a bucket — this prevents the ceiling from collapsing under the weight
- Document the leak location, size, and timing with photos and video
- Once rain stops, check the attic space above the leak location for the entry point
- Contact a licensed Savannah roofer for professional assessment within 48 hours
Preventing Future Heavy Rain Leaks
Once you've experienced a heavy rain leak, the underlying vulnerability won't fix itself — it will only worsen with each subsequent storm. Here are the most effective preventive measures for Savannah homes:
- Upgrade flashing: Replace aging galvanized flashing with aluminum or copper at all wall-to-roof transitions, chimney corners, and valley intersections
- Install ice and water shield: Self-adhering membrane in valleys, eaves, and around penetrations provides a watertight backup layer that prevents water from reaching the deck even when shingles fail
- Oversize gutters: Standard 5-inch K-style gutters are inadequate for Savannah's intense rain rates. Upgrading to 6-inch gutters with 3x4-inch downspouts prevents overflow-related fascia damage
- Annual professional inspection: A trained eye catches developing vulnerabilities — deteriorating sealant, loose flashing, pipe boot cracks — before they become active leaks during the next heavy rain event
Professional Leak Detection Methods
When the source of a heavy rain leak isn't obvious, professional roofers in Savannah use several diagnostic methods: controlled water testing (simulating rain on specific sections while an observer watches from the attic), infrared thermal imaging (detecting moisture-saturated areas in the deck and insulation), and electronic moisture mapping for flat roofs. These methods identify the actual entry point, which can be 10-20 feet away from where water appears inside the home — water travels along rafters and underlayment before dripping through the ceiling.