Chimney flashing might seem insignificant, but this little piece of metal around your chimney plays a big role in protecting your home. It keeps water leaks and damage at bay and maintains the integrity of your chimney.
There are different types of chimney flashing. Each type serves a particular purpose according to chimney size, shape, and style. To make the selection easier, we’ve compiled a guide including the 5 most common types of chimney flashing and their uses.
What Is Chimney Flashing?
Chimney flashing is a metal sheet installed at the meeting point between your chimney and roof. It creates a watertight seal that protects against water penetration and moisture damage. Chimney flashing might not cross your mind very often, but if it’s been a few years since you last performed a thorough roof inspection, now may be a good time to consider it.
Properly installed and maintained flashing can last up to 30 years – on the condition that you check it periodically and repair any damage as soon as it appears. If damaged, it must be repaired to protect your chimney and prevent roof leaks.
Why Is Chimney Flashing Important?
When it comes to your chimney system, chimney flashing shouldn’t be overlooked. This sheet metal wraps around the chimney and extends to the roof, adjusting differences in inclination and pitching to stop water from leaking into your home.
By installing chimney flashing, you’ll avoid issues such as:
- Discoloration
- Water stains
- Water leaks
- Decay
- Rust
- Rot
- Mold
- Collapse
5 Types of Chimney Flashing
Different types of chimney flashing are used according to chimney size, shape, and style. Here’s a closer look at the 5 most common types according to their purpose.
1. Step Flashing
Step flashing is the most common type of flashing used in residential roofing projects. It’s san L-shaped piece of metal placed under the roof’s shingles and along the walls of the chimney. The term “step flashing” is derived from the process itself, which is completed step-by-step: you install a shingle, then a piece of chimney flashing, then another shingle until the entire wall of the chimney is covered and protected.
Pros of Step Flashing
- Simple to install
- Budget-friendly
- Suitable for most chimney shapes and sizes
- Easy way of directing water away from the chimney and preventing water damage
Cons of Step Flashing
- Not as long-lasting or reliable as apron or counter flashing
2. Apron Flashing
Apron, or continuous flashing, is typically installed along the base of the chimney, but unlike step flashing, a long piece of sheet metal is bent to perfectly fit the chimney and roof.
Pros of Apron Flashing
- Less time-consuming to install
- Ideal for larger chimneys
- Offers greater protection in areas with more precipitation
Cons of Apron Flashing
- More expensive than step flashing
3. Cap Flashing
Cap flashing is generally made of metal and placed around the chimney flue to block water from entering the chimney.
Pros of Cap Flashing
- Very useful in mitigating water damage in areas with heavy snow or rainfall
- Available in a variety of materials, including lead, aluminum, copper, stainless steel, and plastic
- Can outlive your roof
Cons of Cap Flashing
- Requires regular inspections and maintenance
4. Counter Flashing
Counter flashing protects the base of the chimney at the meeting point with the roof, preventing water damage. It goes over the step or continuous flashing and extends down the walls of the chimney. Counter flashing is applied in two layers: the first layer is the base, applied at the bottom of the chimney and sealed to the chimney using waterproof sealant; the second layer is inserted into the chimney brickwork.
Pros of Counter Flashing
- Prevents water damage
- More reliable long-term
Cons of Counter Flashing
- Is more time-consuming to install
- Costs more than step flashing
- If installed incorrectly, it will fail quite quickly
5. Cricket Flashing
Cricket flashing is typically used for bulkier chimneys that are regularly exposed to pooling water on the roof. A cricket is a triangle-shaped, wooden structure built behind the chimney to direct water away from the chimney. Once the shape is created, metal flashing is added on top for optimal water damage protection.
Pros of Cricket Flashing
- Ideal for larger chimneys
- Prevents the pooling of water on the roof
- Keeps chimney masonry from rotting
Cons of Cricket Flashing
- Is more time-consuming to install
- More expensive
Types of Chimney Flashing Materials
If you’re in the market for new chimney flashing, there are several flashing materials to choose from.
Aluminum flashing is likely the most popular choice among homeowners due to its low cost and easy installation. It can be powder-coated to match home accents and has incredible durability. Aluminum is also quite resistant to rust, which makes a difference long-term.
Metal flashing, usually steel, is likewise commonly used to manufacture chimney flashing. It’s not only durable, but it has excellent anti-rust properties. Metal flashing is typically used on metal roofs and chimneys.
Copper flashing is the obvious, yet more expensive, choice if you want durability, curb appeal, and a lightweight material. Copper also never rusts and can withstand any weather conditions. The benefits offered by copper flashing generally outweigh the cost.
Lead flashing is a supple and malleable material typically used on homes in the northern part of the country. Though less popular with homeowners due to its toxicity, the right contractor can easily use it to create a watertight seal.
Vinyl or PVC flashing offers similar benefits to metal flashing minus a complicated installation process. The downside? It lacks durability and resistance to extreme weather conditions. It’s usually used for step flashing and incorporated into the shingles.
Signs You Need To Replace Your Chimney Flashing
Like any part of your home, chimney flashing can become damaged over time, allowing water to penetrate your living space. If that’s the case, replacing your chimney flashing may be unavoidable. Look for these signs indicating the need for new flashing.
Leaky Chimney: If you see water dripping from your chimney or moisture forming around it, you’ll need to address it immediately. Chimney leaks will allow water to penetrate your roof and reach your interior walls, causing mold formation and health risks.
Cracked Chimney Crown: The chimney crown protects your chimney’s structure from Mother Nature. If it’s cracked, water will seep into your chimney, the masonry surrounding it, your walls, and your home. This issue also represents a doorway for insects and other pests to enter your living space.
Damaged Chimney Mortar Joints: Chimney mortar joints keep the chimney in place and secure. If you notice damp mortar joints, call a contractor for advice. Damaged mortar joints won’t be able to support your chimney.
Flaking Chimney Tiles: If you notice flakes of chimney tile at the base of your fireplace, it could mean your chimney liner has been damaged. In such a case, replacement is crucial to prevent a mix of the gasses inside and the air outside, which can be a serious fire hazard.
Deteriorated Chimney Bricks: Once in a while, check your chimney bricks for signs of peeling, loosening, crumbling, or flaking, which indicates damage that a professional contractor should immediately address.
Signs of Corrosion: Some flashing types are more vulnerable to damage than others. Rust stains around your chimney flashing indicate a need to have your flashing replaced as soon as possible.
Cost of Replacing or Repairing Your Chimney Flashing
Leaks around your chimney area, especially in the attic insulation or on your ceiling or walls, could be signs of missing or damaged chimney flashing. If it needs to be replaced, here is the cost breakdown for professional installation vs DIY.
Professional Installation Cost
On average, you can expect to pay anywhere from $250 to $1,400 for professional chimney flashing replacement. The final price will depend on your chimney size and type, the flashing you choose, your roof type, and the labor hours needed.
Consider the following:
- If you have a metal chimney and a stainless steel flue duct, expect to pay between $300 and $600 to flash the exterior of the chimney.
- If you have a brick or stone chimney, replacing the flashing will likely fall in the $500 to $1,500 range. For a large chimney with multi-flue ducts, the price can easily reach $1,000.
- Customized flashing manufactured to match your roofing material will cost more.
- You’ll need to budget for cleaning, inspection, and other chimney services.
DIY Installation Cost
You’ll typically pay between $65 and $100 for a DIY job. But while this may be the more budget-friendly option, there are other considerations to remember:
- Safety: The job will take place 30 feet or higher above the ground, which means using an extension ladder is a must. Once you access your roof, every step you take must be steady, careful, and secure, as you will likely be walking at an angle. When removing the old flashing, be careful not to cut or injure yourself handling the metal sheets. Don’t start the job without safety eyewear, boots with plenty of grip, heavy-duty gloves, and a harness on hand.
- Experience: For a DIY project, you must know how to accurately measure the angles of your chimney and roof to start.
- Materials and tools: You’ll need the proper materials and tools to complete a flashing replacement job. Cut and bend your chosen flashing material before climbing your ladder for the installation.
- Time and working conditions: Start work in the early morning before the sun has had a chance to bake your roof. Adhesive and shingles tend to become more flexible in hot weather, making them more challenging to handle. The heat also can be a mitigating factor if you’re not used to spending a lot of time working outside.
For flashing repair, you’re looking at spending between $200 and $500. A roofing contractor will determine whether you’ll need to repair or replace your chimney flashing entirely.
FAQ About Chimney Flashing
Once the flashing material is cut and installed in the chimney’s mortar joints, caulk is used to seal the edge of the chimney flashing and attach it to the chimney securely. Caulk prevents water from getting behind the flashing and causing damage.
The flashing should extend at least 6 inches up the chimney and the same length under your roof’s shingles, though the longer, the better.
It all depends on your home’s design, budget, and preferences. Many homeowners choose a bare, silver finish, though this type can create glare and look slightly too bright. An alternative is to opt for black or natural brown flashing.
Call a Professional
Chimney flashing is an essential part of your roofing system. If yours is due for repairs or replacement, the expertise of a roofing craftsman is as crucial as the materials used for the installation. We can connect you to a roofing professional to ensure a smoothly-running project and a final result that won’t disappoint.
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