Short answer: Start in the attic with a flashlight during or right after rain, and look for wet wood, water stains, drips and daylight. Trace the water uphill, because it often travels along rafters before it drips. The most common sources are flashing around chimneys, vents and skylights, damaged or missing shingles, and valleys where two roof slopes meet.
A stain on the ceiling rarely sits directly under the hole in the roof. Water can run along roof boards, rafters and pipes for several feet before it drips onto the ceiling. This guide explains how to find a roof leak safely, from inside the house, and when to call a roofer.
Do not climb onto the roof, especially when it is wet, windy or icy. Most leaks can be traced from the attic and the ground, and roof work is best left to a roofer.
Step 1: Check the attic
- Go into the attic during or soon after rain, with a good flashlight.
- Step only on joists or boards, never on the ceiling drywall between them.
- Look for wet or dark stains on the roof deck, rafters and insulation.
- Look for drips, mold spots and rusty nails.
- On a dry day, turn off the attic light and look for daylight coming through.
Step 2: Trace the water uphill
Once you find wet wood, follow it upward toward the peak of the roof. The highest wet spot is usually closest to where water enters. Mark it with chalk or tape so the roofer can find it from outside.
Step 3: Look at the likely sources
- Flashing: the metal around chimneys, vents, skylights and walls is the most common leak point, especially when sealant cracks
- Shingles: missing, cracked, curled or lifted shingles after wind or hail
- Valleys: where two slopes meet, water flow is heavy and debris collects
- Plumbing vent boots: rubber collars around pipes crack in sun
- Ice dams: in cold climates, water backs up under shingles near the edge
- Gutters: clogged gutters can push water under the roof edge
Step 4: Check from the ground
With binoculars, look for missing or lifted shingles, damaged flashing, cracked vent boots and debris in valleys. Check gutters for piles of granules, which can mean shingles are wearing out.
The hose test
If the leak only happens in some rain, a roofer may use a hose test: one person runs water over sections of the roof, starting low and moving up, while another watches in the attic. This should be done by or with a roofer, not by climbing on the roof yourself.
Leaks that look like roof leaks
- Attic condensation: warm, damp air from the house condenses on cold roof boards in winter and drips. Better ventilation and air sealing fix it.
- Air conditioning drain lines: a clogged line or pan in the attic can overflow in summer.
- Bathroom fans venting into the attic: moist air soaks insulation and boards.
- Plumbing leaks: a pipe in the ceiling can drip when no rain has fallen.
If a stain appears in dry weather, one of these is more likely than the roof.
What to do until it is fixed
- Catch drips with buckets and protect belongings
- Move insulation away from wet spots so it can dry
- Have a roofer put a tarp over the damaged area if a storm is coming
- Photograph the damage for insurance
Read about roof repair and our guide to water leaking from the ceiling.
Quick answers: how to find a roof leak
How do I find where my roof is leaking?
Check the attic during or after rain, trace wet wood uphill to the highest wet spot, and look at flashing, vents and valleys nearby.
Why is the ceiling stain not under the leak?
Water often runs along rafters and roof boards before it drips, so the hole is usually uphill from the stain.
What is the most common cause of roof leaks?
Damaged or failed flashing around chimneys, vents and skylights, followed by damaged shingles.
Can I fix a roof leak myself?
Temporary measures such as buckets and a tarp help, but roof repairs should be done by a roofer for safety.
Who should I call for a roof leak?
A roofer to find and repair the leak, and a water damage company if the ceiling or insulation is soaked. Sifixit can connect you with local providers.
Related
This guide covered how to find a roof leak. For more background, see Ready.gov’s severe weather advice, and if you need help, Sifixit can connect you with a local provider.
This guide is general information for homeowners, not professional, insurance or safety advice for your situation.
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