Can You Have 2 Fireplaces on One Chimney?

In this article, we will discuss if you can have 2 fireplaces on one chimney. Most houses only have one fireplace which needs one chimney. On the other hand, in case your house needs two fireplaces to keep it warm do you need to install another chimney as well? We will find out the answer to this question below.

Can you have 2 fireplaces on one chimney? Fireplaces on multiple levels can also share one chimney structure. Since the fireplaces are on different stories of the home, the chimney extends from the lowest floor through the roof. Each fireplace can face the same direction if you want since they will not block each other.

The typical house has either no fireplaces or one fireplace. The amount of fireplaces in a house is not restricted statewide. Some local communities have restrictions on the number of fireplaces in a residential dwelling, but that is a rare occurrence.

Can Two Fireplaces Share the Same Chimney?

Fireplaces on multiple levels can also share one chimney structure. Since the fireplaces are on different stories of the home, the chimney extends from the lowest floor through the roof. Each fireplace can face the same direction if you want since they will not block each other.

Shared flues can create fire and smoke spread hazards and carbon monoxide hazards in buildings. In some communities or jurisdictions for certain cases, it is permissible to share a single chimney flue among more than one heating appliance or fireplace. But important safety constraints still apply.

Can You Have Shared Chimney Flues?

Shared fireplaces often share the same flue. It is also common for a single flue to serve both a heating appliance, such as a boiler or water heater and a fireplace. Shared chimney flues mean that the flue for venting waste gases out of a building is shared among two appliances. If the construction is not done properly there is a danger of fire spread, combustion gas, or carbon monoxide hazards.

Each appliance that produces combustion gases needs to have its dedicated flue to vent combustion gases safely out of the building. If this is not the case, dangerous gases may be inadvertently conducted from one area of the building to another.

Can Two Gas Fireplaces Share the Same Chimney Flue?

Two gas-fired appliances, such as a water heater and heating boiler, may be vented into the same chimney flue if your local authority approves of this installation. If the gas appliances are on separate floors, there is a potential increased risk of fire or gas leaks between floors. Depending on the particular circumstances, additional installation requirements may be imposed, or sharing the same chimney flue may not be permitted.

If the chimney is an older, typically clay-lined, masonry construction, venting gas-fired heating equipment into it may be unsafe. The lower exhaust gas temperatures produced by gas-fired appliances may mean inadequate draft and risk of fatal carbon monoxide poisoning of building occupants.

Can You Have Multiple Fireplaces in Multiple Rooms?

You can have multiple fireplaces in multiple rooms, or you can have one fireplace in multiple rooms. A trendy feature of fireplaces includes putting it on a wall between two rooms so you can see the fire from both sides. There are even some fireplaces that conjoin three rooms. The benefit of this style is that you can have multiple rooms with a fireplace while only needing one chimney. You can also check out this article that discusses if an electric fireplace needs a vent. We have shared an in-depth discussion about the topic.

What is a Double Flue Chimney?

A double flue is a set of two flues that are routed out of a structure together. These types of flues are sometimes inserted into existing chimneys, and in other cases, a chimney may be designed from the start with the intent of being a double flue. For an example of what this type of flue looks like, a perusal of photographs of large mansion houses may provide some examples, as many of these structures use double flue designs to minimize the number of holes in a roof, and as a result chimney pots are often seen in pairs which emerge from the same chimney.

Why Use Double Flue?

There are several reasons to use a double flue. In cases where multiple fireplaces, woodstoves, or other heating devices are attached to the same chimney, that chimney may not be able to generate enough draw to handle all of these attachments. As a result, lighting a fire upstairs might cause smoke to belch out downstairs. In these cases, enclosing a double flue inside the chimney allows for two fireplaces to be on separate flues. The design also makes it possible to cap one flue to prevent drafts when a room is closed off without impairing the function of another device connected to that chimney.

A double flue can also be used when two different types of fuel-burning devices are attached to the same chimney. For instance, someone might use a double fuel to vent an oil heater and a gas stove through the same chimney. Since different fuels combust at different temperatures, leading to differences in the temperatures of the flue gases they produce, it may be necessary to use separate flues to get an appropriate draft, or for safety reasons.

Can Two Gas Fireplaces Share the Same Chimney?

Two gas fireplaces can share the same chimney. Fireplaces that are on different levels could also be part of the same chimney. Because the fireplaces are situated on different levels of your home the chimney is extended from the floor that is lowest to the roof. Each fireplace can face the same way and you can choose to do so because they won’t hinder one another. A double-sided fireplace may be used to construct a multi-level fireplace.

✅ Video – Transform a Masonry Fireplace into a Better Heat-Producing Fireplace

Magic Mountain Chimney Sweeps Fireplaces & Grills shared the video below on YouTube. It discusses how to transform a masonry fireplace into a better heat-producing fireplace. Watch the video to learn more about the fireplace, stove, and chimney system of your house.

Chimney Materials

Both chimneys and flues are available in a variety of materials, including stainless steel, concrete, pumice, clay or ceramic, and plastic. Concrete, pumice, and clay or ceramic are collectively known as masonry chimneys. Plastic flues can only be used with low-temperature condensing appliances, and some stainless steel chimney systems and liners are designed only for use with gas-fired appliances.

Clay and pumice chimney systems however are suitable for use with wood, multi-fuel, oil, and gas appliances. Factory-produced pumice, clay, and ceramic chimney systems can be retrofitted, but they tend to be reserved for new builds as they require foundations, and their construction is best left to a skilled bricklayer.

How Do You Maintain Your Chimney?

The main cause of smoke coming into the room from an existing chimney that once worked is a blocked flue. The solution is to get the chimney swept. Insufficient air coming into the room can also cause blow-back. Bear in mind that, traditionally, houses had lots of draughts while today they are often too airtight for an open fire. If you don’t give the fire sufficient oxygen, it will find its own, pulling great gulps of air down the chimney and belching smoke out into the room. If necessary, add a vent to an outside wall adjacent to your stove or fireplace.

Can You Have a Fireplace Upstairs?

Upstairs Fireplaces Oftentimes in older homes, you will find a fireplace on multiple stories of the home. This makes sense because homes that previously used fireplaces as their primary heating source would naturally need more fireplaces. In most cases, these fireplaces share one chimney but use their separate flue to exhaust smoke and byproducts. This type of setup is normal and nothing to be alarmed about, however, some unique issues can arise for homeowners with fireplaces on two floors.

How Does a Fireplace Work?

A column of heated gas accumulates in a chimney’s smoke chamber, which then pulls, or draws, more heat from the fire below and channels it up the flue. This draw is the most important operation in a fireplace as it keeps smoke and gasses flowing out of your home. If you remember from middle school science, heat rises. You can observe this principle in a hot air balloon, where heat and gas from a burner fill the balloon causing it to rise.

What Fires Can You Have with a Traditional Chimney?

There are no major restrictions on the type of fire you can have with a traditional chimney. The internal diameter of the chimney will be 7 inches or more and so can cope with most things thrown at it. Class 1 or 2 solid fuel fires, electric fires, gas fires, and gel fires are all suitable. Just remember that your fireplace chamber will need to be able to accommodate the fires. For example, an inset electric fire will need a different setup than a solid fuel fire. You can also check out this article that discusses if gas fireplaces are worth the money. We have shared an in-depth discussion about the topic.

Why Do I Need a Chimney Cap?

Chimney caps are not required, but it is highly recommended that you have a chimney cap installed for several reasons. Chimney caps protect your home and your family by preventing rain, debris, and animals from entering your chimney. You can install a standard chimney cap on your chimney, or you can install beautiful custom chimney caps that will compliment your home’s current aesthetics. We have also shared this article titled, which is better: vented or ventless gas fireplace? You can check out the article for more tips and information.


You have reached the end of this article that discusses if you can have two fireplaces on one chimney. We have found out that it is possible to have two fireplaces in one chimney. If you have multiple fireplaces in your home, ask your local chimney professional if you need to add another chimney or not. Thank you for reading!

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