What Is The Best Way To Insulate Inside A Fireplace
Tips & Tricks

What Is The Best Way To Insulate Inside A Fireplace?

Insulating your fireplace can improve energy efficiency and reduce air leaks. There are many more reasons to insulate a fireplace. How to make wood burning fireplaces properly insulated? What is the best way to insulate inside a fireplace? The answers you need are below in this text!

Why is it worth insulating a fireplace?

There are people who love admiring a crackling fire. If you are one of those people, you would probably like to reduce the inefficiencies of your fireplace. Even ninety percent of the heat that is produced by your fireplace goes out of the chimney. If you think that an unused fireplace costs you nothing – you’re wrong.

Leaks in the fireplace vents, fans, and the chimney may allow heated air to escape. The same applies to the fireplace door (if a fireplace has doors). This is a problematic issue in winters. There is another problem during the summer months – previously mentioned leaks can let hot air inside your home. In other words, the main reason for insulating a fireplace is not to let small gaps lead to air leakage. Insulating your fireplace really pays off!

How to properly insulate a fireplace?

We already know that the main purpose of a fireplace insulation is reducing air leaks. We can do it by insulating a chimney liner, insulating your fireplace doors and by insulating the chimney walls. All these actions can help you restrict heat loss and as a result, you can save money. The words “the best way to insulate inside a fireplace” can refer to every method of insulating mentioned in this text. How to insulate a fireplace? Let’s see together.

Insulate a chimney liner

Chimney flue liner is a long tube which connects the top of your chimney and the top of your fireplace. It is known for its flexibility, as they are usually made of flexible stainless steel. Thanks to such chimney liners, the heat and smoke produced by your fireplace aren’t dangerous for your home.

What’s more, a fireplace insert stops smoke from leaking through seams in the chimney and possible small cracks in a fireplace. We cannot fail to mention the fact that chimney flue liners minimise the risk of fire – they add another layer between the wooden structure of your home and warm air and sparks. 

Insulating a chimney liner makes sense because it doesn’t allow moisture caused by large temperature differences to accumulate. Moreover, hot air remains hot for a longer period of time. At the same time, smoke and gases can travel out of your home completely safely. One more advantage of insulating your chimney liner is that you don’t expose yourself to additional costs, as the heat loss is reduced when your fireplace isn’t in use. If you want to insulate a chimney flue, we suggest using chimney liner kits – this is one of the safest options.

Insulate the door of your fireplace

If you own a fireplace with a metal or glass door, you ought to make sure that the seal is complete – it cannot be broken, cracked, or missing. It is of high importance to check your seal out. If there is something wrong with the seal of the doors, then cold air will be able to seep inside your home even if your fireplace isn’t used.

Cracked or broken seals may allow carbon monoxide and smoke into your home in situations when you light a fire in your fireplace. It causes a potential danger to your health! Summing up, insulating the door of your fireplace is nothing but making sure that the seal is unbroken. If it isn’t in a good condition, just replace it with a new one. Don’t hesitate to buy a new seal if the old one shows any sign of wear.

Insulate the walls of your fireplace’s chimney

The exterior walls of your house prevent air leaks. See, it’s the same with the walls of your chimney – they have a similar function. What you need to remember about is to leave an air gap between your chosen insulation and the fireplace itself. All this to avoid combustion.

When insulating, focus on the cavities on the wall between studs inside the fireplace. Focusing on the fireplace’s metal components is a mistake! What you also can do is to add a barrier of heat-resistant material above the insulation. That will help to separate materials that are possibly combustible from the source of the heat. Remember to always follow building codes and local guidelines when insulating!

What else to remember about when insulating an inside of your fireplace?

Bear in mind that insulating a fireplace cannot be successful without the right heat-resistant materials. Among other things, you will need a spray foam and heat temperature stove paint, based on silicone resin, perfect for painting all kinds of fireplaces, heaters, furnaces, boilers, barbecues and so on. Such a spray paint is heat-resistant up to 800C. It will certainly be useful!

What’s more, you can choose from many products which can seal a chimney flue like, for example, an inflatable fireplace plug. Such products are not expensive. Installing it isn’t a problem at all. Fireplace plugs are available in different sizes and shapes, so they can fit the dimensions of your fireplace. They can close off your fireplace temporarily. You can use other fireplace sealers, such as balloon-shaped sealers or a decorative cover. 


Insulating an inside of the fireplace is all about creating “plugs” of insulation. You have to compress insulation and then put it into the opening. Thanks to that the insulation will slightly expand and fill the hole. It should be done from the top. All you need to do then is to use galvanized sheet metal to cover the fireplace opening in order to prevent air leakage – it’s that simple! Remember that insulating a chimney liner, fireplace doors, and the walls of the chimney is equally important!

Photo by Rafael Leão on Unsplash

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.