Aging Flashing on 1990s Long Island Colonials

Large colonial and cape-style homes built on Long Island from roughly the late 1980s through the early 2000s share a roof design: multiple dormers, hip roofs with several valleys, skylights and chimneys. Many are reaching an age where the flashing, more than the shingles, deserves attention.

Why flashing from that era ages

Roofing details of the period often depended on sealant or mastic. That was the standard practice of the time, and it created a vulnerability that was always going to be time-limited.

• Dormer counterflashing. Step flashing at dormer cheek walls was often installed correctly, but the counterflashing over it was frequently bent metal sealed with caulk, without being embedded in a reglet or mortar joint.
• Skylights. Curb flashing was sometimes membrane tape and sealant around the opening, which works as long as the sealant is alive.
• Valleys. Open metal valleys depend on edges bedded in roofing cement, and that cement ages.
• Chimneys. Counterflashing was often surface-applied and sealed with caulk or mastic instead of being embedded in the mortar joints.

The common thread is a sealant that has to stay flexible, bonded and watertight. Exterior sealants do not last forever. When they crack and lift, water gets in.

Shingles and flashing age separately

If the shingles look fine from the street, owners assume the roof is fine. Shingles and flashing are different systems and they age on different timelines. Shingles can have years of life left while the flashing at every dormer relies on cracked caulk.

The same applies when a roof is replaced. If the work covers shingles only and leaves the original step flashing, counterflashing, valley metal and skylight flashing in place, the old water management under the new shingles is still the old water management. That is why we treat flashing as part of the scope of a reroof, not an afterthought.

What failure looks like inside

Water from failed flashing rarely shows up directly below where it enters. It travels along the deck and sheathing and appears somewhere else, often well away from the source. By the time you see a ceiling stain, the path has often been active for a while.

Typical signs:

• Staining at the ceiling near, but not at, a dormer wall. The entry is often at the dormer step flashing rather than a shingle above the stain.
• Water at the head of a second-floor dormer window, from flashing failure at the dormer base.
• Staining or peeling paint in a ring around a skylight curb, which usually points to curb flashing and not the skylight glass.
• Staining or mold on the attic sheathing near a valley.

What to look at

Roof work should be done by a professional, and a roof inspection is the safest way to know where you stand. Here is what an inspection looks at.

Dormers. Step flashing should be individual metal pieces layered with each course of shingles. Counterflashing should be embedded, not just caulked to the siding.

Skylights. A properly flashed skylight has step flashing and counterflashing at the curb, integrated with the shingles the way a dormer is. On a wide curb, a cricket (a small peaked diverter) on the uphill side keeps water from pooling there.

Valleys. Is the valley open metal, closed-cut or woven? Open metal valleys need the bedding checked. Closed-cut valleys need the cut edge checked. Woven valleys on an older roof need to be checked for wear at the crease.

Chimney. Counterflashing should be embedded in reglets cut into the mortar joints. Surface-applied counterflashing sealed with caulk depends on that caulk staying intact.

What a complete scope covers

On a multi-dormer colonial of this period, a reroof that addresses the flashing includes step flashing at the dormers, embedded counterflashing at dormers and chimneys, new valley metal, skylight curb flashing, and crickets where they are missing. When you compare quotes for a house like this, ask what the flashing plan is. The quote should say what is being replaced, and a thorough inspection includes lifting shingles at key points to see what is underneath, not only looking from the ground.

These houses were built for their time. The geometry is complex and the roofs are large, which is exactly why the detail work deserves attention. To have your roof looked at, get a quote.