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  • Writer's pictureD&G Exteriors

Chimney Flashing: What It Is and Why It's Important

Chimney flashing is a crucial component of any roofing system. It is the metal sheet placed around the base of a chimney where it meets the roof to prevent water from entering the home. Chimney flashing is essential to prevent water damage, which can lead to costly repairs.


There are several types of chimney flashing available, including step flashing, continuous flashing, and saddle flashing. The type of flashing used depends on the design of the roof and chimney. The flashing material can also vary, with copper being the most popular choice due to its longevity and malleability.


Proper installation of chimney flashing is critical to ensure that it functions correctly. Flashing should be installed by a professional roofer to ensure that it is done correctly. If the flashing is not installed correctly, it can lead to leaks and water damage. Regular inspections of the flashing should be conducted to ensure that it is in good condition and functioning correctly.


Understanding Chimney Flashing

Chimney flashing is a crucial component of a roofing system, as it helps to prevent water from entering the home by creating a waterproof barrier. It is the material that creates a barrier between the chimney's masonry and the roof to prevent water from seeping in and causing damage. Understanding the different types of chimney flashing and the materials used to make it is essential to ensure proper installation and maintenance.


Types of Chimney Flashing

There are several types of chimney flashing, including step flashing, base flashing, counterflashing, and cap flashing. Step flashing is a series of L-shaped pieces of metal that are installed under each shingle and overlap each other to create a watertight seal. Base flashing, also known as apron flashing, is installed at the base of the chimney and extends over the shingles to create a waterproof barrier. Counterflashing is a second layer of metal that is embedded in the chimney mortar joints and folded down to cover the top of the step flashing. Cap flashing is installed over the top of the chimney to protect the chimney from water damage.


Materials Used

The most common materials used to make chimney flashing are copper, aluminum, steel, lead, and galvanized steel. Copper is the most expensive and durable option and is often used in high-end homes. Aluminum is lightweight and easy to install, making it a popular choice for DIY homeowners. Steel is strong and durable but may rust over time. Lead is an excellent option for flat roofs and is easy to mold to the shape of the chimney. Galvanized steel is a cost-effective option and is often used in commercial roofing.


Importance of Proper Installation

Proper installation of chimney flashing is crucial to ensure a watertight seal. If the flashing is not installed correctly, water can seep into the home and cause damage to the roof, walls, and ceilings. It is essential to hire a professional roofing contractor to install or repair chimney flashing to ensure that it is done correctly. Homeowners should also inspect their chimney flashing regularly to ensure that it is in good condition and make any necessary repairs promptly.


In summary, chimney flashing is a critical component of a roofing system, and understanding the different types of flashing and the materials used to make it is essential to ensure proper installation and maintenance. Homeowners should hire a professional roofing contractor to install or repair their chimney flashing and inspect it regularly to ensure that it is in good condition.


Installation Process

Preparation

Before installing chimney flashing, it is important to ensure that the roof and chimney are in good condition. Any existing damage or issues should be addressed before installing flashing. The following tools and materials are necessary for the installation process: chisel, hammer, circular saw, tin snips, roofing cement, roofing shingles, asphalt shingles, L-shaped pieces of step-flashing, polyurethane caulk, roofing membrane, and urethane caulk.


Applying Base Flashing

The first step in installing chimney flashing is to apply base flashing. This involves cutting a piece of roofing membrane to size and securing it to the roof using roofing cement. The base flashing should be positioned so that it extends up the chimney by at least 6 inches and over the roof by at least 12 inches.


Securing Step Flashing

Once the base flashing is in place, the step flashing can be installed. L-shaped pieces of step-flashing should be installed along the sides and top of the chimney, with each piece overlapping the previous one by at least 2 inches. The step flashing should be secured to the roof using roofing cement, and each piece should be secured to the chimney using polyurethane caulk.


Adding Counterflashing

After the step flashing is in place, counterflashing can be added. Counterflashing is a piece of metal that is installed over the step flashing to provide additional protection against water intrusion. The counterflashing should be cut to size and bent to fit the contours of the chimney. It should then be secured to the chimney using urethane caulk.


Final Sealing

To ensure that the flashing is watertight, it is important to apply a final layer of sealant. This involves applying a bead of polyurethane caulk along the edges of the flashing where it meets the roof and chimney. The caulk should be smoothed out using a caulk gun or a putty knife to ensure that it is evenly distributed.


Overall, installing chimney flashing is a complex process that requires careful attention to detail. By following these steps and using the right tools and materials, homeowners can ensure that their chimney flashing is installed correctly and will provide reliable protection against water intrusion.


Common Issues and Maintenance

Chimney flashing is an essential component of a brick chimney that keeps water from seeping into the structure and causing damage. However, over time, flashing can wear out or become damaged, leading to leaks and costly repairs. In this section, we will discuss some common issues with chimney flashing and how to maintain it to prevent water damage.


Identifying Potential Leaks

One of the most noticeable signs of a leaky chimney flashing is water stains on the ceiling or walls near the chimney. Homeowners should inspect their chimneys regularly for any signs of water damage, rust stains, or rusted flashing. Snow and rain can cause damage to the flashing, causing it to separate from the chimney or roof. In addition, old flashing can become brittle and crack, allowing water to seep in.


Regular Inspection and Repair

Regular inspection and maintenance can prevent costly repairs and ensure the chimney flashing remains watertight. Homeowners should inspect their chimney flashing at least once a year, preferably before the winter season. During the inspection, they should check for any signs of damage, rust, or cracks in the flashing or mortar joints. If any issues are identified, homeowners should hire a professional to repair or replace the flashing.


Preventing Water Damage

To prevent water damage, homeowners should ensure that their chimney flashing is waterproof and weather-resistant. They should also ensure that the flashing is installed correctly and tightly sealed to the roof and chimney. If the flashing is damaged or worn out, homeowners should replace it as soon as possible to prevent water from seeping into the chimney structure.


In conclusion, maintaining chimney flashing is crucial to prevent water damage and costly repairs. Homeowners should inspect their chimney flashing regularly, identify potential leaks, and hire a professional to repair or replace any damaged flashing. By following these simple steps, homeowners can ensure their chimney remains safe and watertight.


Advanced Considerations

Chimney Crickets and Saddles

In some cases, a chimney may be located on a roof slope where water runoff flows towards it. This can cause water to accumulate on the roof, leading to leaks and damage. To prevent this, a cricket or saddle can be installed on the roof to divert water away from the chimney.


A cricket is a peaked structure that is installed on the high side of the chimney. It is designed to redirect water around the chimney and prevent it from pooling. A saddle, on the other hand, is a structure that is installed on both sides of the chimney. It is designed to create a channel for water to flow around the chimney and prevent it from accumulating.


When installing a cricket or saddle, it is important to ensure that it is properly sized and installed. A mason or roofing professional should be consulted to determine the appropriate size and installation method for the chimney.


Custom Flashing Solutions

In some cases, standard flashing solutions may not be appropriate for a particular chimney. This may be due to the size or shape of the chimney, or the roof slope. In these cases, custom flashing solutions may be required.


Custom flashing solutions can be created by a sheet metal shop or a roofing professional. These solutions may involve the use of non-standard materials or the creation of custom flashing pieces to fit the specific dimensions of the chimney.


When considering custom flashing solutions, it is important to ensure that the solution is appropriate for the chimney and roof slope. A professional should be consulted to determine the appropriate materials and installation method for the custom flashing solution.


Overall, advanced considerations such as chimney crickets and saddles and custom flashing solutions should be taken into account when installing chimney flashing. By working with a professional and ensuring that the appropriate solutions are used, homeowners can ensure that their chimneys are properly protected from water damage and leaks.


Choosing a Professional

When it comes to chimney flashing, it's important to choose a professional who has experience in this specific task. While some homeowners may choose to tackle the project themselves, it's important to consider the potential risks and drawbacks.


When to Hire a Roofing Contractor

If a homeowner does not have experience in roofing or chimney work, it's best to hire a roofing contractor to complete the task. A professional roofing contractor will have the necessary skills, tools, and safety equipment to complete the job safely and effectively. Homeowners should look for a contractor with experience in chimney flashing specifically, and should ask for references and proof of insurance before hiring.


Ensuring Quality Workmanship

When hiring a professional for chimney flashing, homeowners should ensure that the contractor uses quality materials and practices proper installation techniques. This includes using safety goggles and a dust mask when cutting or drilling into masonry, as well as ensuring a tight fit for the flashing to prevent water intrusion.


The contractor should use lead flashing or other waterproofing materials to create a watertight seal between the chimney and roof sheathing. They should also use galvanized roofing nails or plastic anchors to secure the flashing to the roof.


The apron and square step flashing should be installed in a way that ensures a tight fit against the chimney, with the slot cut into the masonry to allow for proper drainage.

Homeowners should also consider having their chimney flashing inspected periodically to ensure that it remains in good condition and is providing adequate protection against water intrusion.


Overall, choosing a professional with experience in chimney flashing and ensuring quality workmanship can help to ensure that a homeowner's chimney remains protected for years to come.

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