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Roofingaka: cap flashingaka: wall flashingaka: reglet flashing

Counterflashing

In Plain English

Metal flashing embedded in a wall that covers and protects the top edge of the roof flashing below it.

Definition

The portion of a two-part flashing assembly that is embedded into a vertical surface (such as a wall, parapet, or chimney) and laps over the base flashing below it. Counterflashing protects the top edge of the base flashing from water infiltration and allows independent movement between the roof and wall assemblies. It is typically made from sheet metal (copper, galvanized steel, or aluminum) and is set into reglets or mortar joints.

Why It Matters in Bidding

Counterflashing is a small line item that carries outsized risk: a roof leak at a wall or parapet transition is a common warranty and callback source, so estimators must confirm whether it is in the roofer's, mason's, or sheet-metal sub's scope. Missed or double-counted flashing scope at trade boundaries is a classic bid gap that surfaces as a change order after award.

Example

Reviewing the roofing scope on a masonry parapet, the estimator clarified in the bid that the sheet-metal sub would furnish and install the reglet-set counterflashing while the roofer provided only the base flashing, closing a coverage gap between the two trades.

Related Terms

FlashingParapetCricketDrip Edge

Frequently Asked Questions

Base flashing is the lower, roof-side component that turns up the vertical surface and seals the roof membrane edge. Counterflashing is the upper piece embedded in the wall that laps over the base flashing's top edge. Together they form a two-part assembly that sheds water while permitting independent movement between the roof and wall.
It varies by project and region, which is why it must be spelled out. It may fall to the roofing contractor, the sheet-metal contractor, or be tied to the mason who sets reglets or rakes mortar joints. Clarifying responsibility in the bid prevents both a coverage gap and double-pricing between trades.
Common choices are galvanized steel, aluminum, copper, and stainless steel, selected for compatibility with adjacent metals and the building's design life. Copper and stainless cost more but last longer and resist corrosion. Material selection affects both unit price and warranty, so estimators should price the specified metal rather than a cheaper substitute.

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