Chimney and Skylight Flashing With a New Roof in Harrisburg, PA

Why these spots leak

Water running down a roof has to get around anything that breaks the surface. On older brick houses in Midtown Harrisburg, Steelton and Camp Hill, chimneys are often the first place a ceiling stain appears. On newer homes in Lower Paxton and Mechanicsburg, skylights added in the 1980s and 1990s are a common source.

Old step flashing that has rusted through or was never woven in with the shingles.
Counter flashing pulled loose from soft, crumbling mortar.
Layers of roofing cement smeared over a joint instead of proper metal.
Skylight seals and frames that have aged past their service life.
Wide chimneys with no cricket, so snow and leaves pile up on the uphill side.

How chimney flashing should be built

The residential code used in Pennsylvania calls for a cricket on the uphill side of chimneys wider than 30 inches. If the mortar joints are soft, a mason may need to repoint before the counter flashing is set.

1Step flashing, one L-shaped piece per shingle course, up both sides of the chimney.
2Counter flashing cut into a mortar joint and bent down over the step pieces.
3An apron piece across the downhill face, lying over the shingles.
4A back pan or a small peaked cricket on the uphill side to send water around.
5Self-adhering ice barrier turned up the chimney under the metal.

Skylights during a replacement

A skylight sits in the roof like a small chimney and needs the same layered flashing. Most makers sell flashing kits matched to each unit. When the shingles come off, you have three choices.

Reflash the existing skylight with a new kit, if the unit itself is sound.
Replace the skylight, if the glass is fogged, the frame is cracked or it has leaked before.
Remove it and deck over the opening, if you no longer want it.

Timing matters

Replacing a skylight a few years after a new roof means cutting into new shingles. If the unit is old, it usually makes sense to replace it during the roof job.

Walls, dormers and porch roofs

The same rules apply where a roof meets a wall: on dormers, on a porch roof against the house, and on the stepped rooflines of Harrisburg rowhouses. Step flashing runs up the roof, and siding or counter flashing covers it. On brick, the metal should be set into the mortar, not glued to the face.

Questions to ask before you sign

Will all step and counter flashing be new, or will any be reused?
Does my chimney need a cricket?
Who handles any masonry work, and when?
What do you recommend for my skylights, and why?

Questions

+Can the old chimney flashing be reused?

Step flashing is woven in with the old shingles and usually comes off with them. Reusing worn metal under new shingles leaves the most leak-prone joint unchanged, so most roofers install new step flashing.

+Is caulk enough to seal around a chimney?

No. Sealant cracks with heat and cold. It can back up a joint, but the metal layers have to do the real work of shedding water.

+Does a skylight need a permit?

Adding a new skylight or making a larger opening is structural and often needs a permit. Reflashing an existing one during a replacement usually does not. Check with your township or borough; see [Pennsylvania roof permits](/questions/pa-roof-replacement-permits).

Chimney and skylight flashing on a new roof