How do you find a roof leak?
Short answer. Start in the attic during or right after rain and follow the water trail uphill from the stain to where it first appears on the decking or a rafter, then check the roof above that point for the usual suspects: pipe boots, flashing at walls and chimneys, valleys, skylights and missing shingles. If nothing obvious turns up, run a controlled hose test one area at a time with a helper watching inside.
Step 1: the attic
- Go up with a strong flashlight during or soon after rain, stepping only on framing.
- Find the wet spot above the ceiling stain, then follow the trail uphill along the decking and rafters. Water often travels several feet before it drips.
- Look for dark stains, rusty nail tips, wet insulation and daylight around penetrations.
- Measure from a fixed point, like a wall or vent pipe, so you can find the same spot from outside.
Step 2: the usual suspects
- Pipe boots: cracked rubber collars, the most common Georgia leak.
- Flashing: step flashing at walls, chimneys and dormers, and missing kickout flashing where a roof edge meets a wall.
- Valleys: debris dams, and worn shingles or nails too close to the center.
- Skylights and vents: flashing, seals and exhaust vent caps.
- Shingles: missing, creased or lifted after wind, and exposed nails.
Use binoculars or a drone from the ground. Stay off steep, wet or high roofs.
Step 3: a controlled hose test
- Pick a dry day and put a helper in the attic with a flashlight.
- Start low, below the suspected area, and run water gently for several minutes.
- Move uphill in small sections. When the helper sees water, you have found it.
- Do not spray water up under shingles; that creates leaks rain never would.
Clues from timing
- Only in wind-driven rain from one direction: flashing or siding on that side.
- Only in very heavy rain: valleys and debris dams.
- On cold, dry mornings: condensation or a ventilation problem, not a leak.
See common roof leak causes and pipe boot leaks.