Expensive materials—you might want to leave this one to a pro.
What you'll need:
TOOLS
Measuring tape
Weighted line (optional)
Caulking gun
Metal snips
Power drill
Masonry drill bit
Gloves
Safety glasses
Dust mask
SUPPLIES
Steel chimney liner kit
Chimney sealant
Pulling cone
Stainless steel screws
Chimney cleaning brush
Rope
Fitting a chimney liner is not the most glamorous home improvement project. However, liners protect your chimney's structural integrity, ensuring it works safely by preventing fires and carbon monoxide poisoning. Here, we walk through how to fit a chimney liner.
Prepping to Fit a Chimney Liner
Before fitting a chimney liner, it's essential to thoroughly clean your chimney to remove any soot, creosote, or debris. Using a chimney brush that matches the size of your flue will help you get the job done right. A clean chimney ensures you will get the proper measurements.
While you're at it, check for any damage. If you're unsure or want to be extra thorough, hiring a professional chimney sweeper can be a great option—they will handle the cleaning and inspection.
How to Fit a Chimney Liner
Accurate measurements are everything when fitting a chimney liner. The correct fit ensures your liner protects your home while optimizing performance. If the liner is too small, it won’t ventilate properly; if it is too large, it might not fit correctly. To fit a chimney liner, you’ll measure the length of your chimney using a long measuring tape or a weighted line. You'll also measure the width and length of your flue (or the diameter, if you have a round flue).
Measure Your Chimney
Photo: Inga / Adobe Stock
Start by measuring the length of your chimney from the top (where the liner will be installed) to the point where your fireplace or appliance connects to the chimney. This length determines how long your chimney liner needs to be. To do this, use a long measuring tape or a weighted line that you can drop down the chimney.
Measure the Flue
The flue allows smoke and gasses to travel up and out of your home. The size of your flue will dictate the diameter or size of the liner you need.
For a round flue, measure the diameter from one side to the other across the broadest part. This straightforward measurement will directly correspond to the diameter of the round liner you need.
If you have a rectangular flue, measure both the width and the length of the flue’s interior.
Keep in mind that stainless steel chimney liners typically come in round and rectangular shapes, but there are also oval options that can fit in spaces where a round liner may not work, such as flue bends.
Consider the Appliance’s Venting Requirements
In addition to measuring the chimney, it’s important to know the venting requirements of your appliance if your chimney connects to a wood stove or furnace. The chimney liner's diameter must match your appliance's vent size to ensure proper airflow.
Check the appliance manufacturer’s recommendations to confirm the appropriate liner size. If your chimney is too large for the appliance, you may need a reducer or adapter to ensure a proper fit.
The chimney cap covers the flue and sits on top of the chimney. It needs to be removed to insert the liner. The steps for removal depend on the type of chimney cap you have. Follow the manufacturer’s instructions or work with a local chimney repair specialist.
Start at the top of the chimney and carefully lower the liner down into the flue. It may be helpful to have a pal assist you.
If your chimney has bends, gently twist and push the liner to help it move through. If you’re struggling, try attaching a pulling cone (a unique tool that helps guide the liner) and use a rope to pull it down.
Once the liner is in place, secure it at the top with the top plate in your liner kit using a drill and the appropriate masonry bit. Then, using your caulk gun, apply a generous bead of high-temperature sealant around the edges of the top plate where it meets the chimney to prevent water from seeping into the chimney. Afterward, reattach the chimney cap. Then, apply more sealant.
With the liner secured at the top, it’s time to connect the bottom end to your fireplace, wood stove, or furnace.
Start by guiding the liner down to the appliance’s flue collar, where it will attach to the fireplace, stove, or furnace. You may need to trim the liner to fit, depending on your setup. Use your metal snips to carefully cut the liner to the correct length, ensuring it fits snugly without any excess that could cause kinks or blockages.
Next, secure the liner to the appliance using the appropriate connector. It could be a clamp, adapter, or collar that came with your purchased kit or the appliance.
Tighten the connection to ensure no gaps where exhaust gasses could escape, then add the sealant. Finally, double-check that everything is secure and properly aligned. A tight, secure connection will help maintain a strong draft, prevent leaks, and ensure your chimney system operates safely and efficiently.
DIY vs. Hiring a Pro
This DIY project is suited for seasoned do-it-yourselfers with the right tools who are comfortable working on the roof. While the steps for this project might seem straightforward, cleaning a chimney and installing a liner can be challenging, especially if there are flue bends. While saving money is appealing, knowing the risks involved is essential.
A chimney repair specialist can handle the installation, ensuring it's done safely and in accordance with local building codes. Additionally, professionals can identify any chimney damage affecting structural integrity that a nonprofessional might miss. Professional chimney liner installation costs between $1000 to $5,000, and liner kits start at around $800.
Frequently Asked Questions
Yes, chimneys with liners still need regular sweeping. While the liner helps protect the chimney and improve efficiency, soot, creosote, and other debris can still build up inside. Regular sweeping is essential to prevent blockages, ensure proper ventilation, and reduce fire risk. Having your chimney inspected and swept at least once a year is recommended, even with a liner installed.
Chimney liners often benefit from insulation, though it is not always required. Insulation helps improve the liner's efficiency by keeping flue gasses hotter, which enhances draft and reduces creosote buildup. It also prevents condensation, which can lead to corrosion. Insulation is important for chimneys on exterior walls or in colder climates. Some building codes may require insulation, so checking local regulations is essential.
Deirdre is a seasoned DIYer and home improvement writer. She believes in the transformative powers of deep cleaning and painting to revitalize any space. Her articles have appeared in HomeLight, The Spruce, Realtor, and more.
Deirdre is a seasoned DIYer and home improvement writer. She believes in the transformative powers of deep cleaning and painting to revitalize any space. Her articles have appeared in HomeLight, The Spruce, Realtor, and more.
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