Flashing is thin sheet metal installed at roof joints and penetrations to redirect water away from vulnerable seams.
Flashing is installed anywhere two roof planes meet, or where something penetrates the roof surface — chimneys, vent pipes, skylights, and roof-to-wall transitions all need it. It works by creating a water-tight metal barrier that shingles alone can't provide at these irregular junctions, directing water back onto the roof surface rather than letting it seep into the gap.
Step flashing (individual L-shaped pieces woven between each shingle course) is used along roof-to-wall transitions and chimneys. Counter-flashing is embedded into masonry or siding above step flashing for a second layer of protection. Valley flashing runs along the internal angle where two roof planes meet. Failed or improperly installed flashing is the single most common cause of roof leaks.
Chimney flashing is one of the most common leak points on a roof — it involves multiple flashing pieces (step, counter, and often a cricket for larger chimneys) that can fail individually over time as sealant ages and metal corrodes.
Yes — flashing repair is typically an isolated, inexpensive repair ($300-$900) that doesn't require touching the surrounding shingles unless they're also damaged.
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