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True Trade Path

Diagnostic guide

Roof Leak

Trace a ceiling stain back to its actual source, which is rarely directly above the visible damage.

System
Roofing
Causes covered
7
You can check
1 without a technician

Stop and read this first

  • Do not go onto a roof to investigate. Falls from roofs are a leading cause of serious injury in and around the home.
  • Water near light fixtures or in a ceiling is an electrical hazard. Shut off the affected circuit.
  • Persistent moisture leads to mold within 24 to 48 hours. Dry the area aggressively while you arrange repair.
  • Photograph everything before any work begins if you intend to file an insurance claim.

Work through these in order

Ordered from most to least likely. Working top down means you rule out the cheap, common causes before paying anyone to look at the expensive, rare ones.

  1. Failed flashing at a penetration

    CommonNeeds a pro
    How to check
    Look for the nearest chimney, vent pipe, skylight or wall intersection uphill of the stain.
    The fix
    A roofer replaces the flashing. Flashing failure, not shingle failure, causes the majority of roof leaks.

  2. Missing or damaged shingles

    CommonNeeds a pro
    How to check
    Inspect from the ground with binoculars after a windstorm. Look for lifted tabs and exposed nail heads.
    The fix
    Individual shingle replacement is straightforward. Widespread damage means evaluating the whole roof.

  3. Ice dam

    CommonNeeds a pro
    How to check
    Leaks appear during a winter thaw, with visible ice ridges at the eaves and icicles along the gutter.
    The fix
    Address the cause: attic air sealing and insulation. Ice dams form because heat escapes into the attic and melts snow that refreezes at the cold eave.

  4. Clogged or failed gutters

    CommonYou can check
    How to check
    Water overflowing behind the gutter, staining at the fascia and soffit.
    The fix
    Clean and re-pitch the gutters. Overflow behind a gutter rots fascia and drives water into the wall assembly.

  5. Condensation mistaken for a leak

    PossibleNeeds a pro
    How to check
    Staining appears in cold weather without rain, often with visible frost on nail points in the attic.
    The fix
    Improve attic ventilation and air sealing. This is a moisture problem, not a roof problem, and roofing work will not fix it.

  6. Failed valley

    PossibleNeeds a pro
    How to check
    Staining below where two roof planes meet.
    The fix
    A roofer rebuilds the valley. Valleys carry concentrated water volume and are a frequent failure point on older roofs.

  7. Deteriorated roof at end of life

    CommonNeeds a pro
    How to check
    Widespread granule loss, curling edges, exposed mat, and a roof over twenty years old.
    The fix
    Replace the roof. Repeated spot repairs on a worn-out roof cost more over two years than replacing it.

Once you know what it is

Step one

Know what it should cost

Get the range before you call, so the first number you hear is not the only number you have.

Step two

Decide repair or replace

On equipment near end of life, the repair is usually the first of several.

Step three

Check the quote

Compare against the typical range and confirm the terms before you sign.

Estimate the repair costAnalyze a quote

What the fix costs

Tools for this decision

Other symptoms