Counter Flashing

Counter flashing is the outer layer of flashing installed over step flashing or base flashing. While step flashing directs water away from the roof, counter flashing covers and protects the top edge of the step flashing, preventing water from getting behind it.

On masonry chimneys, counter flashing is typically embedded into the mortar joints and overlaps the step flashing below. This allows each piece to move independently as the roof expands and contracts with changing temperatures while maintaining a watertight seal.

Without properly installed counter flashing, water can work its way behind the flashing and eventually cause damage to the roof deck, wall sheathing, ceilings, or interior finishes.

Where Is Counter Flashing Used?

Counter flashing is commonly installed:

• Around masonry chimneys

• Along brick or stone walls where the roof meets the wall

• At some roof-to-wall transitions

• Anywhere step flashing requires additional protection from water intrusion

It is most often used with masonry construction, while other siding materials may use different flashing details depending on the wall system.

How Does Counter Flashing Work?

Counter flashing works together with step flashing to manage water.

Step flashing is installed between each course of shingles to direct water down the roof.

Counter flashing overlaps the step flashing and protects its upper edge, preventing water from getting behind the flashing.

Together, these two flashing systems create multiple layers of protection that help keep water moving down the roof instead of into the home.

Typical Cost

Counter flashing is typically included when replacing chimney flashing or when a complete roof replacement requires new flashing.

The cost depends on the size of the chimney or wall, the existing flashing conditions, and whether new masonry work is required.

Because flashing failures are one of the most common causes of roof leaks, replacing damaged or improperly installed counter flashing is an important part of many roofing projects.

Benefits

• Helps prevent roof leaks

• Protects roof-to-wall intersections

• Covers and protects step flashing

• Allows the roof and chimney to move independently

• Improves long-term waterproofing

• Helps extend the life of the roofing system

• Provides a clean, finished appearance

Why It Matters in Michigan

Michigan's heavy rain, snow, and freeze-thaw cycles place constant stress on chimneys and roof-to-wall intersections. Properly installed counter flashing helps prevent water from entering these vulnerable areas while allowing normal movement between the roof and masonry.

When combined with step flashing and quality roofing materials, counter flashing helps protect your home from costly water damage.

Our Recommendation

At VanderLaans, we inspect all chimney and roof-to-wall flashing during every roof replacement.

If the existing counter flashing is damaged, improperly installed, or no longer providing adequate protection, we recommend replacing it as part of the roofing project. Proper flashing is just as important as quality shingles and is essential to the long-term performance of the roofing system.

Did You Know?

Many chimney leaks are caused by flashing problems—not the chimney itself. Even the best shingles cannot prevent water intrusion if the flashing around the chimney is damaged or improperly installed. Properly installed step flashing and counter flashing work together to protect one of the roof's most leak-prone areas.