Everything You Need to Know About Chimney Liners
Chimneys are a source of comfort. Despite the fire that blazes in them, they bring a lot of comforts. Especially in the winter when we actually use them.
But chimneys are extremely dangerous. Chimney fires are responsible for more than 22,000 house fires, 20 deaths, and $125 million in property damage each year. Without proper maintenance and care, this could easily happen to you.
Your chimney liner needs to be in great condition, perfectly fit the fireplace or insert, and clean from any obstructions. If not, creosote build-up will speed up, corrode your liner, and potentially catch fire.
The cracks in your liner will allow embers or flames to escape the flue and potentially reach the wood frame of your house.
You can imagine the catastrophic results from that…
Today, I’m going to share with you everything you need to know about your chimney liner. And hopefully, by the end of this post, you’ll have an understanding of what a chimney liner is and why it’s important to keep it in good condition.
Table of Contents
What is a Chimney Liner?
All chimneys built these days are supposed to be lined, either with clay tile, cast-in-place flue, or a metal liner. The type of liner really depends on the building codes of your area.
For example, in Virginia, many of the historical homes require that the chimney liner be a cast-in-place liner (more on what that is later) to keep the structural integrity.
Chimney liners serve three main functions: protect your house from catching fire, protect brickwork and mortar, and keeping your chimney working efficiently.
Protect Your House from Cathing Fire
There’s a lot of woodwork near your chimney. When there isn’t anything to keep the fire away from the wood, it can catch fire a lot quicker than you think.
One study showed that the heat in an unlined chimney caused the adjacent woodwork in a house to catch fire in only 3.5 hours. Even the smallest crack in the liner can have devastating results.
Protect Brickwork and Mortar
Heat, gases, creosote, and other natural byproducts of fire are acidic and can literally cause your chimney to deteriorate and crumble. Without a liner, your chimney will wear down at a much faster pace than if you had a liner.
As the mortar joints from the brickwork erode, heat from the chimney can transfer to other combustibles (like wood) and cause a fire.
Or the eroded mortar can allow dangerous gases, including carbon monoxide, to leak back into your home, also leading to devastating results.
The byproducts are naturally occurring, but a lined chimney will face fewer issues and will stand much stronger for a longer time.
Keeping Your Chimney Working Efficiently
Your chimney is a complex system that relies on a phenomenon called the Stack Effect, which is basically the concept behind “warm air rises.”
Your chimney and its liner require a perfect fit for the gases to flow out of the chimney at an effective rate. If the gases and smoke don’t flow out fast enough, you’ll likely see excessive creosote build-up.
And we already know that creosote contributes to corrosion and deterioration of the chimney’s liners.
Why Would I Need a New Liner?
You would need a new liner to help keep your chimney operating safely and efficiently. Chimney problems are notorious for following the domino effect, where one domino falls causing the rest to fall as well.
For example, with your liner, if it is damaged or sized incorrectly, you’ll have problems with the draft and flow. If you have problems with the draft and flow, the chimney smoke and gases can’t escape fast enough.
The moisture in the smoke and gases encourage excessive creosote to stick to walls of your liner, further restricting the draft and flow, eventually corroding the liner, and potentially causing a chimney fire.
During our inspections, we often see four main reasons for relining a chimney: inaccurate liner sizing, cracks and other hazards, no liner at all, or it’s been more than 20 years since you’ve replaced your liner.
Inaccurate Liner Sizing
Probably the most common reason for needing a new liner is that the one you have isn’t properly fit for the fireplace or stove you have.
There are a lot of folks out there that are the DIY-type and install the chimney liner themselves. The problem with this is they buy a liner that doesn’t fit the stove or fireplace properly.
This is one of the reasons that we have to always recommend you trust professionals to deal with your chimney.
Cracks & Other Hazards
A lot of older homes were built without chimney liners. Even today, we see a lot of newer houses being built, where the builder doesn’t know the code for chimneys and doesn’t install liners.
As I’ve mentioned before, this is very dangerous since it’s been shown that fire in chimneys without liners can cause the rest of your house to catch fire in about 3.5 hours.
No Liner at All
It’s Been More than 20 Years
Chimney liners go through it all. They are there every time you need them as you light your fire. But even if you maintain your liner properly, get it inspected annually, and swept every year, you should still only expect it to last 15-20 years.
Of course, the time frame really depends on your maintenance frequency and the type of liner that you have. But a good rule of thumb is having it replaced every 15-20 years.
The only way to know if you can have it longer or if you need a replacement sooner is with regular inspections.
How Can You Tell If Your Liner is Messed Up?
Most of the time, you’ll have no idea that your chimney liner is messed up. But sometimes, there might be a sign that presents itself to you that says: “fix me!”
Any damage to your chimney liner could cause much further damage, so it’s important to get an annual inspection and sweep, but also keep an eye out on your chimney for these signs.
Rust is not good in any situation. Rust is the enemy of your chimney liner. And when you see it, it’s time to get a new liner.
Rust in your fireplace or on your damper can ruin your mortar too, so it’s not something that you want to take lightly. Both of those could be signs that your liner is rusty too.
And keep an eye out on your flue tiles, as cracked tiles are another sign of chimney rust.
The mortar around your chimney liner needs to be in good condition. Damaged mortar will be a clear sign that your chimney needs to be relined.
This happens because the chimney lining is no longer working efficiently and not pushing out the smoke. The smoke will cause the mortar to corrode and deteriorate in no time.
Or if your liner has cracks, it could allow water to seep into the mortar, eventually damaging the mortar that way.
If you see rotting wallpaper or discoloration around the wallpaper near your chimney, you may have pretty big problems. You’ll likely have a chimney leak.
And if you can see the effects of the leak, then it’s gotten pretty bad and is far along.
Spalling is when the stone or bricks on your chimney starts to reduce in size disproportionately due to an increase in the salt content. This is a result of water leakage and your liner needs to be repaired before you use your chimney again.
Your chimney crown is one of the most important protectors of your whole chimney. It helps protect your chimney from all sorts of bad weather. If it becomes cracked, you know that you have a problem.
The issue may not be apparent yet, but it will be if you don’t get it fixed. Cracked crowns can’t protect their chimneys efficiently, so you’ll more than likely have a lot more issues further down the road.
What Can You Do If Your Liner is Messed Up?
The obvious answer is to have it fixed. But the way you fix it and what you do to fix it has to depend on the kind of chimney liner that you have and what you’re going for.
There are three types of chimney liners: clay tile, metal, and cast-in-place. Each one has a different price point, life cycle, and installation requirements.
Clay tile liners are usually the least expensive to install and are the most common ones that we see. Regular cleaning is the only thing you need to do with these. They do a great job withstanding heat and deposits of corrosive byproducts, like creosote.
Over time, you can expect your clay tiles to deteriorate.
When the mortar joints between the tiles corrode and crack, you’ll certainly face carbon monoxide leaking into your house.
Cracks also mean that the heat from the fire will be transferred out of the liner and to combustible materials. This can easily start a fire.
Clay tiles are best used when your chimney is first built. That’s because they’re difficult to retrofit into an existing chimney, especially if your chimney isn’t straight. Because of this, replacing tile liners is a very labor-intensive task.
We’d need to break through chimney walls in several places just to remove the old tiles and replace them with the new tiles. And the low cost of the tiles doesn’t save money in the end because of the cost of installation labor.
Metal liners can either be aluminum or stainless steel. We typically recommend and prefer the stainless steel liner because they usually come with a lifetime guarantee and can withstand the smoke and weather forever. So long as you maintain them, of course.
Aside from the lifetime guarantee, metal liners are pretty awesome since they are flexible and easy to place down your chimney.
Stainless steel liners are more expensive to buy, but installation costs are relatively cheap and they last for a long time.
A cast-in-place liner is created with poured cement. Literally casting a liner in place.
These flues are designed to withstand the heat, condensation, and acid that comes with using your fireplace. And they have excellent insulation properties that could help the fireplace to burn cleaner, reducing creosote accumulation.
Cast-in-place liners last a long time, around fifty years, and many chimney experts believe that the cast-in-place liners help stabilize clay flues that are unsound. This can happen because the cement is poured either inside the chimney walls or in the existing flue.
Cast-in-place can be less invasive and labor-intensive as rebuilding clay tile liners, but it depends on a lot of factors. It’s a tough job that requires special tools and trained professionals.
Questions to Ask When You’re Getting a New liner
Even with all of this information about liners, when you have a chimney technician recommend that you get a new liner, you should be curious about how he or she came up with that recommendation.
Especially if you didn’t notice any of the signs I mentioned before.
I’ve put together this list to help you out.
#1 Why Does My Chimney Need a New Liner?
Your technician should be able to answer why. And he or she should have listed any problems with your chimney in the condition report for your chimney during the inspection.
#2 If There’s Damage, Can You Show it To Me?
A professional chimney technician will be able to show you with pictures or a video the condition of the inside of your chimney flue. Like a doctor evaluating an MRI, your chimney technician will be able to point out any deficiencies in your flue.
#3 How will the liner fix the problem?
If your technician is recommending you have a liner installed, then he or she should be able to tell you what the liner will do to fix the problem.
#4 What will you have to do to the chimney so the liner will fit in the flue?
Just like I mentioned before, there’s a lot that is involved with clay liners and cast-in-place liners. Your technician should be able to explain the process to you.
#5 What liner do you recommend installing?
There are three basic categories of chimney liners: heavy, high-performance light, and light. You should know which type of liner (metal, cast-in-place, and clay tile) and the category of the liner that is in your chimney.
#6 Will the liner be insulated?
Insulation is required for any liner used for venting and solid fuel appliances. You should ask your technician if he or she plans to insulate the liner.
If not, then ask why.
#7 Is there a warranty?
You’re going to want your liner to come with a manufacturer’s warranty. The best warranties cover chimney fires and can be transferred to the next owners of the house.
If there is a warranty and it requires the liner is installed by a certified professional, then be sure to check the company’s certifications.
#8 Is it UL listed or just tested to UL standards?
The most widely recognized listing for a chimney liner is a genuine Underwriter Laboratories (UL) listing. Not all liners have a genuine UL listing but have been tested to UL standards by organizations that aren’t the Underwriter Laboratories.
#9 What alloy of stainless steel will the liner be?
The most common alloy for wood, pellet, gas, and oil appliances is 316Ti because it is more resistant to the corrosive elements common to gas and oil flue gases. But very high-efficiency gas appliances will need the AL29 4C alloy, which has the highest resistance to corrosion.
#10 How will the chimney liner affect venting performance?
Your chimney liner will need to be perfectly fit to your stove, furnace, and fireplace so that it can vent the harmful gases out of your home like it’s designed to do.
Tips for Hiring a Chimney Company
Navigating through all of the chimney companies in your city can be a chore all on its own. And it makes sense, too.
Hiring anyone to come into your home to fix something like your chimney shouldn’t be a task you take lightly.
So I created a list that you can use to make sure you make the right decision, when you need someone to help you in your home.
Questions to Ask
When you’re hiring a chimney company, you should always ask the following questions before allowing them to come into your home:
- Can the company provide references?
- Does the company carry a valid business liability insurance policy?
- Does the company ensure that a certified chimney technician will be on the job?
If they guarantee all three of those, then you are in a good spot. The technicians don’t necessarily need to be certified by the CSIA, but I do recommend putting in a bit more due diligence before accepting a certification that’s not by the CSIA.
This is because certifications are a tricky thing, especially in an unlicensed industry like ours. Any company can craft a list of job-related questions and sell them as an exam and certify those who pass.
I recommend you take a few extra minutes in your research before making your hiring decision to learn more about the certification the company has. Here are a few tips to make sure the certification is reputable:
- Is the word “certified” just part of the business name or is it an earned designation?
- Is the certifying body a for-profit business or non-profit?
- Does the certification need to be maintained and renewed through continuing education as the industry evolves, or is it well enough to be certified through a one-time exam?
- Is the certifying body well-established or are they relatively new to the scene? New doesn’t mean “bad” but you should make sure the requirements for certification are more or at least equally stringent as those of more established certifications
- Is the mission statement of the certifying body focused on educating and protecting homeowners or is it more focused on making it easier to earn a certification?
- Does holding the certification require following a code of ethics?
If you can answer all of these questions, then I think it will be safe to allow the company in your home to work on your chimney.
It doesn’t matter if you are in Roanoke, Lynchburg, Blacksburg, or some other city anywhere in the USA — if you have any questions about the safety of hiring a chimney company, please don’t hesitate to email me at firstname.lastname@example.org or call me at 540-225-2626. I’m happy to help!
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