Roofing Glossary

Apron Flashing

Apron flashing is the wide, flat piece of metal installed on the uphill side of a chimney, skylight curb, or similar penetration — the side facing the ridge. It catches water running down the roof and aprons it out over the shingles on either side.

Think of it as a miniature watershed: the apron sits under the uphill shingles and extends out over the penetration's top edge, so water flowing down the slope is diverted around the obstacle rather than pooling against it.

Apron flashing works together with step flashing on the sides and counter flashing above. On chimneys, the apron is often soldered or sealed to the pan at the chimney's base for a continuous watertight assembly.

Why It Matters

The uphill side of any penetration is where water pressure is greatest. A missing or undersized apron lets water drive straight under the uphill shingles — a classic and preventable leak pattern.

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