Counter Flashing vs. Flashing

Attribute	Counter Flashing	Flashing
Function	Prevents water from entering behind the vertical wall cladding	Prevents water from entering the intersection of roof and vertical wall
Location	Installed above the base flashing	Installed at the intersection of roof and vertical wall
Material	Usually made of metal	Can be made of metal, plastic, or rubber
Appearance	Visible on the exterior of the building	May be hidden beneath other building materials

Introduction

When it comes to protecting a building from water infiltration, flashing and counter flashing are two essential components of the roofing system. Both serve the purpose of directing water away from vulnerable areas and preventing leaks. While they may seem similar in function, there are key differences between counter flashing and flashing that are important to understand in order to make informed decisions about roofing systems.

Definition

Flashing is a thin strip of material, typically metal, that is installed at vulnerable areas of a roof to prevent water from seeping in. It is commonly used around chimneys, skylights, and other protrusions on the roof. Counter flashing, on the other hand, is a second layer of flashing that is installed over the top of the primary flashing to provide an extra layer of protection against water infiltration.

Material

Flashing can be made from a variety of materials, including aluminum, copper, and galvanized steel. Each material has its own advantages and disadvantages in terms of durability, cost, and appearance. Counter flashing is typically made from the same material as the primary flashing to ensure a seamless and watertight seal.

Installation

Flashing is installed at the same time as the roofing material and is integrated into the roof system. It is typically fastened with nails or screws and sealed with roofing cement or caulk. Counter flashing is installed after the primary flashing is in place, with the top edge tucked under the siding or masonry and the bottom edge sealed with caulk or mortar.

Function

The primary function of flashing is to direct water away from vulnerable areas of the roof and prevent leaks. It is designed to be a barrier against water infiltration and is essential for maintaining the integrity of the roof system. Counter flashing serves a similar purpose, but it provides an additional layer of protection by covering the top edge of the primary flashing and preventing water from getting behind it.

Appearance

Flashing is typically visible on the exterior of the building and can have a significant impact on the overall appearance of the roof. It comes in a variety of colors and finishes to match the roofing material and blend in with the architecture of the building. Counter flashing is designed to be more discreet, as it is installed over the top of the primary flashing and is not as visible from the ground.

Maintenance

Both flashing and counter flashing require regular maintenance to ensure they remain effective in preventing water infiltration. Inspecting the flashing for signs of damage, such as rust or corrosion, and repairing any issues promptly can help extend the life of the roof system. Cleaning out debris and ensuring that the counter flashing is properly sealed are also important maintenance tasks.

Cost

The cost of flashing and counter flashing can vary depending on the material used, the size of the roof, and the complexity of the installation. Copper flashing, for example, is more expensive than aluminum or galvanized steel. Counter flashing adds an additional cost to the roofing system, but the extra protection it provides may be worth the investment in the long run.

Conclusion

Flashing and counter flashing are essential components of a roofing system that work together to protect a building from water infiltration and leaks. While they serve similar functions, there are key differences in their installation, material, appearance, and maintenance requirements. Understanding these differences can help building owners and contractors make informed decisions about the best roofing system for their needs.