Why Does My Fireplace Smoke? – 11 Causes of a Smoky Fireplace and Their Solutions

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List of 11 Reasons for a Smoky Fireplace – And What to Do About It

So, you have a fireplace or wood stove that is smoking into the house, it’s annoying, smelly and unsafe. Possibly you have called a chimney sweep or repairman to the house who could not solve the problem.

Over recent years in my chimney and fireplace business, there has been an increase in complaints of smoking fireplaces and cold air infiltration into the house via downdrafts (cold air coming down the chimney and into the house).

Fortunately, none of these complaints have occurred on a chimney I have rebuilt/repaired, or a wood stove I have installed!  I usually get called in on an existing situation that has gone on for a long time that seems to be a mystery to everyone.

Public awareness of indoor air quality and its potential effect on personal health has increased, as it should have.

At any rate, there are a number of possible reasons why a fireplace can smoke into a house, and luckily there are quite a number of possible solutions.  In fact, you might be able to solve the problem with a “solve-all” simple solution!

What’s Here:

1. Cause Unknown ("I don't know what's causing my fireplace to smoke.")

No matter what is actually causing it, when a fireplace smokes into a room there is a downdraft coming in to the fireplace rather than up and out of it through the chimney flue.

There are a couple of solutions that are generally effective, and will almost always correct the problem.

#1 Solution: Reverse the Draft Direction with a Chimney Fan

Most effective and highly recommended “solve-all” solution

Recommended:  Enervex Chimney Fan (for Solid Fuels)

While this might not seem like THE cheapest solution right off the bat, chances are that it will be the best one.  This fan is quite effective for pretty much any downdraft, “smoky fireplace” issues, and is an excellent quality product that will very likely last a long time, and save you some cash in the long run.

The Enervex chimney fan powerfully and literally sucks air and smoke from the chimney flue, removing the “smoke in the house” problem.

You can have it installed by a chimney professional, or you can probably do it yourself pretty easily.  (Full installation instructions are available.)

1. Determine Which Size You Will Need
  • Have a tape measure handy
  • Determine which fan you will need (Important – you need a chimney fan specifically for solid fuel):
    • Follow the manufacturer’s online guide – here is a link to their guide which will ask you for dimensions and other information about your fireplace and chimney.  Once through the guide, you will have the answer as to what type and size fan to buy.
2. Purchase the Fan
3. Install the Fan – DIY

#2 Solution: Install a Smoke Guard for Your Fireplace

Another really good “all cause” solution.

Recommended: HY-C Fireplace Smoke Guard

A fireplace smoke guard is another good “solve-all” solution – something that you can do no matter what is causing the downdraft.

The way it works is actually pretty interesting – it reduces the size of the fireplace opening, creating a better “chimney flue to fireplace opening” ratio, which better controls the amount of airflow from the fireplace.

It’s also a lower-cost solution and is a big time saver!

(The brand we recommend is the HY-C fireplace smoke guard – it’s top quality, quite easy to assemble and install.)

1. Determine Which Size You Will Need (4″, 6″ or 8″)

**Note: These instructions assume that your fireplace width is somewhere between 28 1/2″ and 48″. Measure the width of your fireplace before proceeding with instructions. 

  • Measure both the height and width (inches) for your fireplace opening
  • Measure flue opening in inches (length and width).
  • Subtract off 4, 6 or 8 inches from the fireplace opening height to account for its size after smoke guard is installed.
  • Now get 2 square inch figures:
    • For your fireplace opening (height after installing smoke guard x width in inches)
    • For your flue opening (length x width in inches)
  • The ratio of your fireplace opening figure to your flue opening figure needs to be 10:1 or less – whichever size meets this ratio should work well.

Note:  If your fireplace opening is smaller than 28 1/2″ or larger than 48″, then you will need a different smoke guard.  These (in my experience) are quite difficult to find for sale online, but you could check with a local specialty store for assistance on finding a size that will work.

2. Purchase the Smoke Guard
3. Install the Smoke Guard – DIY
  • Get a phillips head screwdriver (the only tool you will need).
  • Assembly and installation instructions should be included with the HY-C smoke guard, but if for some reason you need them, you can find them here. (Opens in a new window.)
  • Assemble the smoke guard according to instructions (pretty simple to do).
  • Installation is also quite easy – it simply adjusts to the size of your fireplace opening (providing it is between 28 1/2″ and 48″).  It’s almost as simple as putting up a shower curtain rod!  (Note:  Caulking is included with the HY-C smoke guard, so you will not need to buy it separately.)

 

2. Cause: Incorrect Chimney Pipe Size

If your chimney pipe (flue) is not sized correctly in proportion to your stove pipe size, this can cause a draft to come into the room from the chimney/fireplace.

Example: The stove pipe is 8” diameter and is connected to a 6” diameter chimney pipe

Solution: Install Correctly Sized Chimney Pipe System

Tip: The chimney pipe (flue) should be the same size as the stove pipe.

Recommended: DuraVent DuraChimney II System

Having a correctly-sized chimney pipe is an important factor for a chimney and fireplace to work correctly.

Measure your stove pipe’s diameter, and compare it to the diameter of your chimney pipe.  If the chimney pipe is smaller in diameter, you need a larger size.

As a pro chimney guy, I recommend DuraChimney II  chimney pipe system, it has a “double wall” which keeps it cool on the outside, and allows for a hot draft on the inside, also allowing for expansion.  It is also quite lightweight, easy to install and it will protect your home with a fire-safe design.

It comes in a range of sizes and lengths.

Note:  You likely will require multiple components for a new chimney pipe system – check manufacturer’s product guide to find out which components you will need.

1. Determine The Size Needed

Generally this is covered above, but the way to determine which size (diameter) you need is to measure the stove pipe diameter, and make sure that your chimney pipe is the same size or a big larger. (It can be up to 25% larger than the stove pipe – but definitely not smaller!)

If you would like to get more official, here is a link to catalog information for the Durachimney II – check p. 5 for the sizing chart.

2. Purchase the Chimney Pipe System

Chimney pipe systems can easily be purchased in quite a number of different diameters and lengths, so you shouldn’t have a problem finding the right sizing.

Important:  Keep in mind that you may require multiple parts for the pipe installation.  Check the Durachimney II Product Guide and/or Installation Instructions for details on which parts you will require.

3. Install the Chimney Pipe

List of you will need:

Installation:

3. Cause: Andirons are Being Used in the Fireplace Instead of a Fire Grate

A fireplace grate tends to be more compact, it burns the wood higher and helps to prevent too much smoke from the fire. (It also keeps wood in the basket better and helps wood fires burn more efficiently.)

Solution: Get Rid of the Andirons, Replace with a Fireplace Grate

‘Nuff said.
Recommended: Vestal Fire Grate

One might not at first think that the quality of a fire grate is important, but if you like to have a nice fire going without worrying about the grate or andirons bending and/or falling apart, this is definitely the way to go.

Fires burn better due to enough air flow coming through, and they burn more efficiently due to the wood staying in one place.

The sturdy construction and obvious thought put into the design makes this a worthwhile purchase – again, we are talking about spending a bit more cash up-front than some other cheaper grates, but the cast iron structure will last much longer than other types and brands.

Various sizes are available for various widths and depths of fireplaces.  (See sizing information below for more information on this.)

1. Determine What Size You Need

Sizing is actually an important factor when purchasing a fire grate. Here are some guidelines on helping you pick a grate with the correct dimensions.

Note:  The below directions refer to a masonry fireplace only – if you have a zero-clearance fireplace, follow the instructions of the appliance for details on fire grate sizing – do not use the below as a guide.

For masonry fireplaces:

  • First, determine how high off the bottom of the fire box the grate needs to be.   If you have a log lighter in your fireplace, ensure that the grate stands up high enough for the lighter to reach the logs.
  • Rule of thumb:  There should be a 3″ clearance between the fire grate and the front, back and sides of your firebox.
    • Measure the depth of the firebox
    • Measure the front width of the firebox
    • Measure the back width of the firebox
    • Choose a size that is 6″ smaller (in length and width) than the dimensions given above.  That will allow a 3″ clearance on all sides.

Here’s why sizing is so important:

  • Too small a grate leads to excessive air flow, and the fire will burn too quickly.
  • Too large a grate could damage the sides of your firebox, and can cause insufficient air flow.
2. Purchase the Fireplace Grate

4. Cause: The Fireplace is in a Basement, or Below Ground Level

Generally a basement area has a lower air pressure than main or upstairs floors.  This can cause a backdraft from the fireplace, often resulting in a smoky fireplace.

Solution: Install a Good Chimney Fan at the Top of the Chimney

A chimney fan can create a reservse “suction” of air, which reverses the direction of the draft.  Voila!  No more smoke (and probably cold, drafty air) coming from your basement chimney!

Recommended:  Enervex Chimney Fan (for Solid Fuels)

Also recommended above as a sort of “cure-all” solution to fireplace drafts coming into a room, an Enervex chimney fan for solid fuel will probably handle your basement fireplace draft problem quite nicely.

This fan comes in different sizes, so chances are very good that there is one that will work perfectly for your chimney.

See section above: “Reverse the Draft Direction with a Chimney Fan” for details on sizing and purchasing the fan.

5. Cause: Burning Wet Wood

Wet firewood can play havoc with your “nice evening in front of the fire.” There is a bit to know about moisture content in wood and its relationship to a “smokeless fireplace.”

Solution: Use Only Well-Seasoned (Thoroughly Dried) Firewood - Use a Good Firewood Rack

Wet Firewood and Fireplace Smoke – What to Know, and What to Do About It

Tip #1:  Fire wood should have no more than 10% moisture content.

Tip #2:  Often times people buy “seasoned” firewood that is not actually that well seasoned (dried).  Also, it is common that people will sometimes try to burn freshly-cut wood, which has far too much moisture content in the wood.

Tip #3:  When there is too much moisture in the wood, just one of the negative results is smoke coming from the fireplace.  Other results are an inefficient fire (not burning hot enough, wasting money on firewood), as well as a buildup of toxic materials in your chimney which can present both a fire hazard and be a real health problem for your home.

1. What to Do About It
  • Buy or cut your wood at least 1 year in advance
  • Make or buy a firewood rack to store the wood properly so that air can circulate throughout the wood to dry it out. Place the wood rack in a dry area if possible. If you cannot, then put a cover over the wood during the rainy season. Take the cover off during hot weather.
2. Where to Buy Firewood Racks and Covers

6. Cause: Lots of Tall Trees Close to the House or House is Close to Canyon Walls, a Cliff or Hillsides

Solution: Install Enervex Chimney Fan, Wind Directional Cap or Rain Cap on Your Chimney

What to Know About Tall Trees, Canyons,  Cliffs, Hillsides and Downdrafts

Having a cluster of tall trees, canyon walls, cliffs or hillsides close to the house can cause a downdraft.

Imagine wind coming over the top of a hillside or cluster of trees, then suddenly dropping down the other side towards your chimney.  This can create quite a draft that will go right down the chimney, and cause smoke to come right out of the fireplace.

Luckily there are some pretty simple solutions to this kind of problem.

What to Do About It – Options:
  • Install an Enervex chimney fan for solid fuel on top of the chimney
    • This reverses the direction of the draft, literally sucking air outward from the chimney flue.  Note:  This is a good “cure-all” solution, no matter what the draft problem is being caused by.  If there is more than one cause for the downdraft, this would be the best solution of the three.
  • Install a Mongoose Metals wind-directional cap, also on top of the chimney
    • A wind-directional cap has a top that rotates according to wind direction, and the design of it creates a vacuum in the chimney flue, thus reversing the direction of the draft.
  • Install a Homesaver rain cap for your chimney
    • A rain cap works in a sort of similar way to a wind-directional cap – it forces drafts around the top of the cap rather than going down the chimney.  This decreases pressure, and forces smoke to flow up into and out of the chimney, and prevents air drafts from moving downward.  My experience is that Homesaver is the best choice.
1. Choose Correct Size to Buy
2. Purchase Your Choice
2. Installation
  • Enervex chimney fans for solid fuel:
  • Wind-directional caps:
    • For round chimney pipe – 
  • Homesaver Rain caps:
    • Installation will depend on which size or specific type of rain cap.  Check installation guide with the product.

7. Cause: The Fireplace Damper is Closed or Partially Open

Solution: Open the Fireplace Damper All the Way

Can’t open your damper all the way?

It may be that the damper is being prevented from opening all of the way due to a rusty damper mechanism or ash and soot have piled up behind the damper over the decades, thus preventing the damper from opening all of the way.

The debris has filled up the “smoke shelf” behind the damper.

A proper chimney cleaning involves cleaning out the smoke shelf.

**I have been on countless jobs where the customer had this problem. I was told that they had the chimney swept every year! There are chimney sweeps out there who will run a brush down the chimney, then collect the money and leave without cleaning out the smoke shelf. I have pulled as much as two 5-gallon buckets of debris out of smoke shelves!

If this is the case, consider finding yourself a different chimney sweep.

8. Cause: A Clogged and/or Dirty Chimney

Solution: Get the Chimney Cleaned by an Experienced Chimney Sweep

Tip:  Not all chimney sweeps are certified and trained through the National Chimney Sweep Guild, but that does not mean that the sweep is incompetent. Actually, I would be willing to bet that there are more chimney sweeps out there that are not part of the guild, and have not trained through the guild than there are guild members.

There are sweeps out there that have been cleaning chimneys for 20 and 30 years without guild accreditation and certification.

Do your research and try to get the “old man” or a new tech who has been properly apprenticed under an experienced sweep.

9. Cause: Air Being Pulled Out Of Chimney From Within the House

Have you noticed that there is a draft coming from your fireplace?  There are a number of reasons this might occur due to an “air pull” coming right from the inside of your house.

Solution: Find Out What's Causing the "Pull" and Correct It - Use This Checklist

  • Furnace Turns On, Creating a Pull From the Chimney
    • Try turning on the heater in the house, and see if a draft starts coming from the fireplace.  If it does, I recommend you consult with an HVAC firm on how to handle this.
  • Lots of Foot Traffic and Doors Opening and Closing in the House Near the Fireplace
    • Try cracking open a nearby window 1-2 inches
  • A Combination of Appliances are Turned On at the Same Time
    • In-home appliances with fans can cause air and smoke to be pulled out of the fireplace.  Example: The range hood, bathroom fan and furnace are all running at the same time when the fireplace starts to smoke into the house.  Experiment with turning off items until the smoking issue stops.  (If this is simply unavoidable or incredibly inconvenient, you might want to consider installing a chimney fan at the top of your chimney.)
  • Cause Unknown

10. Cause: The Chimney is on the Side of the House and is Exposed to Cold Temperatures

When a fireplace is on the side of the house and is exposed to the cold, this can make the chimney flue cold, which can cause a temporary lack of upward air direction flow (until the flue is warmed up).

Solution: Heat up the Chimney Flue

  • Roll up some paper or use a long section of cardboard, light on one side and hold up into the chimney flue.  Do this for a bit of time until the draft reverses.
  • You can also light a quick, hot fire using lots of kindling-sized, dry wood. Do this for about 30 minutes in order to heat up the chimney flue. 

11. Cause: The Chimney Was Not Built Tall Enough

When a chimney is too short, it will cause a downdraft into the fireplace, and into the house.

Solution: Increase Height of Chimney

Have the chimney built up taller so that it is at code height (if under code height) or to the point where a decent draft occurs.

Sometimes a chimney has to be built TALLER than code height in order to get a good draft.

Final Note on How to Stop a Fireplace from Smoking

Given the number of years of experience I have had in the fireplace and chimney industry, I have learned that there is almost always a solution for a fireplace that smokes into a room.

I hope that the list of causes and solutions above helps you out – feel free to let me know if you have any further questions on this, or leave a comment below!

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