Installation & How-To Guides

Often called chase tops, chimney chase covers are essential metal coverings designed for wood-framed boxes that rise along a home's side or protrude from the roofline to house a chimney flue. A chase cover acts as a vital shield for your home, preventing harsh weather and pests from entering the cavity where your flue or chimney liner runs. While masonry or brick chimneys typically utilize concrete crowns, a chase cover can also be a smart choice for masonry applications depending on your specific needs.

It might seem daunting to think about replacing your chimney chase cover but we have outlined everything in our guide below.

Chimney Cap vs. Chimney Chase Cover: What’s the Difference?

One of the most common questions we get from homeowners is "Do I need a chimney cap or a chase cover?" Because both components live at the very top of the roof and are designed to keep water out, the terms are frequently (and incorrectly) used interchangeably.

Understanding the difference is crucial for properly diagnosing leaks and ordering the correct replacement parts.

The Chimney Chase Cover

A chimney chase cover is the large metal pan that seals the entire top opening of your chimney's structure (the "chase").

• Location: It covers the wood framing, brick veneer, or siding that makes up the physical footprint of the chimney.

• Function: It acts exactly like a roof for your chimney structure. Its job is to prevent rain, snow, and ice from entering the walls and rotting the wood framing or damaging the interior masonry.

• Design: It is usually custom-measured to fit the exact dimensions of your chimney and features a central hole (with an extruded collar) where the chimney pipe passes through.

The Chimney Cap

A chimney cap is a smaller, separate component that attaches directly to the top of the metal flue pipe or clay chimney tile.

• Location: Installed exclusively on top of your chimney pipe that comes out from the chase cover.

• Function: It acts as a cap for the pipe itself. It stops rain from falling straight down the flue and into your firebox.

• Design: It usually has a solid metal lid and wire mesh sides, although some caps are designed without wire mesh. For normal operating locations, the mesh allows smoke to vent safely while preventing birds, squirrels, and leaves from entering and blocking the exhaust.

Do You Need Both?

Generally Yes... A complete, weather-tight, and safe chimney system requires both components working together.

We like to think of it this way: The chase cover protects the structure of your chimney, while the chimney cap protects the inside of the pipe and your fireplace. If you have a chase cover but no cap, rain will pour directly down your flue. If you have a cap but a rusted or missing chase cover, water will bypass the pipe and damage the interior walls of your chimney chase.

What are Chimney Chase Covers Made From?

Chimney chase covers are made from four main types of materials: galvanized steel, aluminum, stainless steel, and copper.

Galvanized Steel

Galvanized steel is the lowest cost option and comes standard on many new home builds. It is known to rust quickly and may need replacement in a short period of time.

Aluminum

Aluminum does not rust, and is considered too soft, and is easily damaged by hail. It is not a good choice for most applications and is hard to get in the required sizes.

Stainless Steel

Stainless Steel is the strongest and most popular of all the available choices. And while it might cost more than galvanized, it doesn't rust and will virtually last forever.

Copper

Copper is the highest quality and costs nearly 2x more than stainless steel options. They are the perfect choice for luxury and historic houses. They do not rust but weather to a protective blue-green patina.

Powder Coating

Powder coating is also available for stainless steel options. With many colors to choose from, including custom blends its easy to find a color that matches your home's look and trim colors.

Signs Your Chimney Chase Cover Needs Replacement

If you have read this far, you likely already know if your chimney chase cover needs replacement. That said, a chimney chase cover needs replacement once you start to see any of these signs of failure.

1. Rust Stains on Your Siding, Roof or Brick

Visible rust streaks are the most common and obvious sign of a failing galvanized steel cover. As the zinc coating wears off, the steel beneath rusts. When it rains, water carries that rust over the edge, leaving ugly orange or brown streaks down the side of your chimney chase or roof. If you see rust, the structural integrity of the cover is at its end of life and needs to be replaced.

2. The "Bird Bath" Effect (Sagging)

A properly built chimney chase cover should have at least four cross-breaks (diagonal creases) that create a slight dome, forcing water to run off the edges. Over time, cheap covers or those subjected to heavy snow loads can begin to sag. If water is pooling in the center of your cover like a bird bath, it is only a matter of time before it begins to rust through or compromises the seal around the flue pipe, allowing water to enter the chimney or chimney chase.

3. You Notice Water Inside the Firebox

If you are hearing a dripping sound or see puddles inside your fireplace after a heavy rainstorm, your chase cover, silicone sealant, or the storm collar above it has likely failed. Water traveling down the outside of the metal flue pipe will drip beyond the flue damper and end up directly in your firebox.

Don’t wait; the longer a damaged or end-of-life chase cover remains in place, the higher the likelihood you will need more extensive repairs to the chimney chase, your roof or siding.

4. You Have Cracked or Missing Sealant

The area where the metal flue pipe comes through the chimney chase cover should be sealed with a specialized high-temperature silicone. UV rays, extreme temperatures, and general weathering can eventually dry out and crack this sealant. If the silicone is peeling, shrinking, or missing entirely, water has a direct path into your home. You can check this during your annual flue cleaning.

5. Visible Holes or Corrosion

During your annual or bi-annual flue cleaning, inspect your chimney chase cover. If you see pitting, flaking metal, or small pinholes in the chase pan, you need a replacement. Once a hole develops, the damage to the wood framing beneath or masonry accelerates rapidly.

How To Measure For Your New Custom Chimney Chase Cover

Measuring your chimney chase cover the first time saves you trips up the ladder, costly returns, and potential water leaks. Because homes and buildings settle and shift over time, don't assume your chimney chase or chimney is perfectly square.

Before you head up to your chimney chase don't forget a tape measure, pencil and a notepad.

1. Measure the Outside Dimensions of Your Chimney or Chimney Chase: Do not measure the existing chimney chase cover and do not assume the chimney or chase is square. Measure the entire length and width of the outside of your chimney chase (the brick, siding, or wood structure). Measure all four sides. If the parallel sides vary slightly, always use the largest measurement. Fireside Tip: Add ¼" to ½" to your final length and width so the metal cover slides on easily without binding against the siding.

2. Find Your Flue Location: You want to make sure the new covers hole aligns perfectly with your existing chimney pipe. To find its location, measure the distance from the outside edge of the chase directly to the edge of the flue pipe on all four sides (labeled as Measurements 1 through 4 in the diagram above).

3. Measure the Flue Pipe Diameter: The outer diameter of your flue pipe is what matters here. Measure the width directly across the top of your existing round metal flue pipe. You need the outside diameter. When we make your cover, our craftspeople will make the metal collar slightly larger than your pipe so it slides over it seamlessly.

4. Determine the Skirt Length: The "skirt" is the vertical metal lip that hangs over the sides of the chimney to shed water away from the structure. Our standard skirt is 3 inches, but if you need to cover old water stains, exposed wood, or damaged masonry, measure down to your preferred depth.

Ready to upgrade your chimney's first line of defense against the elements? We make ordering a custom chase cover simple and stress-free.

Use your new measurements to shop our stainless steel and copper options online. If you need help or want a second opinion on your dimensions before placing your order, do not hesitate to reach out! Call our support team at 1-877-486-8119 or drop us an email at sales@firesidechimneysupply.com for personalized, hands-on assistance.