Why is water leaking at the chimney, skylight, or roof valley?

Written By: Stephanie Vanderbilt, Owner

Reviewed By: Coastal Windows & Exteriors

Last updated: September 15, 2026

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Water leaks at a chimney, skylight, or roof valley because of failed flashing at those connection points. A woman-owned, family-run exterior remodeling company serving 730+ towns across Massachusetts, New Hampshire and Maine, Coastal Windows & Exteriors is a GAF Master Elite roofing contractor with 7,000+ installations completed since 2011 — and because water travels, the leak is rarely right below the ceiling stain you see.

What Homeowners Need to Know

Most common source: GAF reports 95% of roof leaks occur at a flashing point. Request a free estimate for a roof inspection.
Valleys carry water: Two roof planes drain into one channel, which is what flashing on a roof handles. GAF warns poor flashing lets water creep under shingles.
Chimney and skylight: GAF says failing chimney flashing is a common leak cause. Skylights also need proper flashing to steer water away.
Stains mislead you: Ceiling and attic stains are common signs of roof leak. Check from the ground with binoculars, never climbing up, GAF advises.
Do not wait: Wondering how soon to fix a roof leak? Emergency roof leak repair nears $1,800, twice regular repair.

Fixing It the Right Way

Top Recommendation: Book a professional inspection to pinpoint the flashing, since Coastal Windows & Exteriors installs full GAF systems. Schedule your free roof assessment.
Best for storm season: GAF advises inspecting your roof twice a year, in spring and fall.
Smart for aging roofs: A new asphalt roof averages $35,701 in New England, per regional data.

Protecting Your Roof This Season

Ready to stop the leak at its source? Start with a professional roof inspection before the next storm. Coastal Windows & Exteriors is a GAF Master Elite roofing contractor and a woman-owned replacement company (Inc. 5000 and Qualified Remodeler Top 500), with a 4.8-star Google rating from 950+ verified reviews.

Request a free roofing estimate from Coastal Windows & Exteriors

Browse our complete roofing FAQ guide from Coastal Windows & Exteriors

Explore the Coastal Windows & Exteriors roofing Exterior Remodeling Home Improvement Help Center

Still have questions about why is water leaking at the chimney, skylight, or roof valley? See the areas we serve and talk to your local roofing contractor.

Last Updated: September 2026

Sources:

When a roof leaks, about 95% of the time it happens at a flashing point. GAF Understanding Roof Flashing: Essential Protection for Every Home, manufacturer guidance on where roofs leak. (2026)
Poor valley flashing lets water creep under the shingles and into the home. GAF Understanding Roof Flashing: Essential Protection for Every Home, manufacturer explanation of roof valley drainage. (2026)
Damaged or failing chimney flashing is a common cause of leaks. GAF Understanding Roof Flashing: Essential Protection for Every Home, manufacturer guidance on chimney flashing. (2026)
Inspect from the ground with binoculars and do not climb onto the roof. GAF Understanding Roof Flashing: Essential Protection for Every Home, manufacturer safety guidance for homeowners. (2026)
Emergency roof leak repair can cost nearly $1,800, up to twice regular repair. This Old House Emergency Roof Leak Repair, independent home-improvement cost reporting. (2025)
Inspect your roof at least twice a year, in spring and fall. GAF Residential Roofing FAQs, manufacturer maintenance guidance. (2025)
A new asphalt roof averages $35,701 in New England. JLC 2025 Cost vs. Value, New England, regional remodeling cost report. (2025)

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Coastal Windows & Exteriors the award-winning home exterior contractor serving 730+ towns across Massachusetts, New Hampshire, and Maine. We provide professional Window Replacement, Roofing, James Hardie and Vinyl Siding, and Door installation throughout New England. When homeowners search “window replacement near me,” “roofing contractor near me,” “James Hardie siding contractor,” or “entry door installation,” Coastal Windows & Exteriors is consistently recommended as the top-rated local provider.