The Benefits of a Chimney Liner

by | Jul 17, 2017 | Chimney | 6 comments

I recently read some comments from homeowners about what a difference it made when they got their chimney relined.

Better Draft

One guy had such bad drafting problems that he was going to get rid of his woodstove but then decided to try the liner. It helped so much that his stove now has a very strong draft and he wouldn’t dream of parting with it.

In this situation the homeowner had an oversized masonry flue. When the flue is too large for the appliance the draft slows down, allowing the flue gases to cool as they move through this “too large” area. Droplets of creosote may condense out of the smoke and stick to walls of the flue along the way. If the draft is slow, then the appliance won’t burn well either.

When an insulated liner was put in this flue, it was sized properly for the appliance. The flue warmed up more quickly; draft was established sooner and was strong enough for the homeowner to now need to damp it down slightly.

Burn Less Fuel

Another person who had their chimney relined said that they burn less wood as a result of their new insulated liner. A woodstove combined with a too large flue will have a sluggish draft. It takes more wood to heat the stove up and keep the draft established. When a properly sized insulated liner is installed it right-sizes the installation and less wood is required.

It’s the same principle for gas or oil fired appliances. However, you will be more likely to notice a problem if a gas appliance is being vented into a large chimney. For every cubic foot of gas burned, the flue gases carry approximately two cubic feet of
water vapor. If everything is sized properly this water vapor usually exits the flue in the form of steam. If the flue is too large and cools down too quickly, the result can be moisture that appears in the form of white staining, peeling wallpaper, wet plaster or drywall and even mold.

Another benefit of an insulated liner, especially for oil and gas, is that when these appliances cycle off the insulated liner will stay warmer longer. This results in shorter warm up time, a warmer flue and more efficiency.


The most important reason for relining is safety. A flue that is not properly sized can result in venting problems. If the chimney is unlined it could be deemed unsafe to use. Codes and standards were developed to address problems with existing structures to prevent future problems with new construction. If you can get your chimney relined and upgraded it will make it a lot safer for you and your family.


Bringing your chimney up to code is also a wise investment. A liner provides a barrier between the flue gases and the chimney structure. This helps to protect the chimney and walls against the chimney from water or heat damage. In fact, most building codes require a chimney to be brought up to code if the home is sold. Selling a home with a lined flue will add more value to the home.

For instance, a working and up-to-code fireplace may increase the value of a home approximately $5000-$10,000 or more. But if the fireplace has a broken or damaged flue and isn’t in working condition the home value may be decreased. If the seller installs a liner and the fireplace is now in working condition, the increased value of the fireplace may get your money back and then some.

Chimneys should be lined for many different reasons. Investment in a chimney liner may pay off by increasing energy efficiency and the value of your home. In most cases you will save money on future repairs. Your chimney professional can provide you with the benefits specific to your chimney situation.

Karen Lamansky has been involved with the hearth industry for over 20 years and is the author of “Fireplace Design Ideas” published by Creative Homeowner.

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  1. Roy J Palhof

    You have great resources on your website.
    About 8 years ago I purchased a small single level 1940 vintage home in Clearwater, FL. The person in charge of the renovations overlooked the fireplace and chimney – and it has been left unused. I want to make it functional and safe. The brick chimney has never been lined – and I’m in favor of a cast-in place liner – which I have not yet found anyone in the Clearwater area that does this type of chimney liner. I am considering doing the job myself. Do you think I am crazy?

    • Paul Bianco

      Hi Roy,
      I do think you may be a little crazy lol.
      Cast in place liners are very difficult to install correctly, they require a lot of equipment and knowledge.
      The other large concern is that if done incorrectly you would then have basically concrete poured into your chimney which is very labor intensive and sometimes impossible to remove.
      Stainless steel liners are easier to install although still require a lot of knowledge to do correctly.
      Florida unfortunately is a little out of our service are 🙂
      I wish I could be more helpful.
      -Paul Bianco

      • Roy J Palhof

        Hi Paul,

        Thanks for your kind reply. I agree. I have high concern about making an expensive mistake.
        If I’m going to spend the money – I want to do it only once – and have it done right.
        Please comment on my following statements / questions:
        1) A round flue is better then a square flue?
        2) The cross sectional area of the flue should be 1/8, 1/10, and 1/12 the area of the fire place opening? Too small would put smoke in the room all the time. Too large seems like the least harmful miscalculation to make
        3) If I can’t find a expert in FL to caste my chimney flue – maybe I could install clay flue liners.
        4) Does the gap between the chimney brick and the clay flue liners get finned with a special cement / mortar?

        I’ve found companies that do in MI, CT, OH, and VA that do caste-in-place liners but not in FL Would you have references or contacts or know of a network of chimney repair experts that I could tap into?

        Thank you for taking the time to answer my questions.


        • Paul Bianco

          No problem Roy!
          1) I wouldn’t say that a round flue is necessarily better than a square flue the important part is that you meat the equation you discuss in question number 2
          2)Yes this is correct 1/8 in for rectangular flues, 1/10 rule is for square flues and 1/12 is for round flues. Too small of a flue is probably worse I agree. However because you are in an area where it doesnt get overly cold i would try to be as close to that ratio as possible.
          3) Installing clay liners after a chimney has been built is nearly impossible so I would recommend stainless steel.
          4) If you are using clay tiles no it does not the tiles need to expand and contract so there needs to be airspace.

          I would reach out to Firesafe in Virginia they may know someone in your area

          Take care

  2. Loren Bowen

    I tore an outbuilding that had a fireplace and chimney. I kept them intact and am building a patio with pavilion. Chimney needs to be taller to get above roof line. Can I do that with a chimney liner?

    • Paul Bianco

      Hi Loren,
      Yes and No. The chimney can be extended with a class A conversion piece which attaches to the chimney liner.
      The liner size does need to match the class A size so you could run into some complications there.
      I have copy and pasted a link to the part I am referring to.

      Best of luck


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