Roofing Glossary

Dormer

A dormer is a box-like structure that projects out from a sloped roof, with its own small roof and usually a window. Dormers add headroom, light, and usable space to attics and upper floors.

Every dormer creates valleys where its roof meets the main roof, plus sidewall and headwall flashing where its walls meet the shingles. That makes dormers one of the most flashing-intensive — and leak-prone — features on a roof. The sidewalls in particular need proper step flashing woven into the shingles.

Dormer roofs are often low-slope, which changes the waterproofing approach: standard shingles may not be appropriate on very shallow dormer roofs.

Why It Matters

Dormer flashing failures are among the most common leak sources roofers are called to fix. If you have a leak near a dormer, the flashing is suspect number one — see our roof repair page.

What to Watch For

• Stains on the ceiling below or beside a dormer
• Rotted dormer sidewall trim
• Debris collecting in dormer valleys

A Maryland Note

Older Maryland colonials and Capes are full of dormers, and many still have original flashing long past its service life.

Questions about your own roof? Request a free estimate or call Nucci Brothers Roofing at (301) 458-1003.