The Complete Guide to Chimney Odors [2020]


Your fireplace is designed to be a source of comfort for you and your family. But sometimes that comfort is interrupted because your fireplace stinks. 

Fireplace smells & odors can come from several different things. Most of the time, the odors are much worse in the summer when humidity is high, on rainy days, and when the conditioner is running. 

While you may be tempted to just spray air freshener to cope with the smell, chimney odors may indicate far bigger problems than an unpleasant smell. 

In today’s post, we’ll talk about some reasons your fireplace smells bad and give you a few things the odors might tell you. 

What the Odors May Tell You

At Patriot Chimney, we get a lot of calls every summer about fireplace odors.

This is primarily due to summer humidity and the fact that barometric pressures push air into the chimney, down your fireplace, and into your house.

When you smell the odors, that usually means you may have a bigger problem with your chimney system.

chimney caps & no caps

Barbeque or Smokey Smell

One of the most common “smell” we hear about during summer is that their fireplace smells like a dirty barbeque grill. 

Even with the fireplace doors and damper closed, you may smell smoke taking over your living room. 

Smokey smelling chimneys and fireplaces are caused by the chimney being full of soot and creosote

A simple chimney sweep will clear away all the creosote, soot, and ash that are causing the smells. 

Mold & Mildew

If you smell mold and/or mildew, it’s pretty clear that you’re facing a chimney leak. 

Not only is your chimney leaking, but it’s been leaking long enough for bacteria and spore growth to develop. 

By the time you smell and notice moldy/mildewy smells, you likely have hidden damage in your chimney system

If you smell mold or mildew, you should give us a call to take a look inside and out of your chimney. With an inspection, we’ll be able to see what’s causing your chimney to smell.

Foul or Decompositon

This one’s the worst smell. 

You can’t mistake the smell of some animal decomposing. 

You might think that something got into your chimney and died. Maybe a squirrel or a bat. 

You’re not wrong, but it doesn’t have to be an animal. It could actually be any organic material that’s decomposing in your chimney. 

That’s leaves, wood, twigs, feathers, animal droppings, etc. 

A chimney sweep can come in and clean the inside of your chimney. We can also assess the top of your chimney to see how these things got in. 

It could be that you need a cap to cover the top of your flue.

4 Reasons Your Chimney Stinks

Most of the issues that cause your chimney to stink can be discovered with a chimney inspection

As I mentioned before, we deal with a lot of complaints of smells, especially during the summer. We hear people saying they have a horrible smell coming from their chimney. 

Here are the top 5 reasons you’ll have a stinky chimney.


#1 – Negative Air Pressure

One of the leading causes of odors coming into your home through the fireplace is negative air pressure

When your home is sealed too tightly, you have the problem where the draft isn’t flowing properly. And mild odors in your chimney will be exhausted back into your home, instead of up and out of your chimney.

This problem comes up a lot of times during the summer after improvements have been made, such as installing a new roof, windows, etc. 

Here are a few solutions that can help resolve the negative pressure: 

  • Keep your fireplace damper closed when you aren’t using your fireplace. If the dampers don’t seal well, this likely won’t be effective. 
  • INstall a glass fireplace screen
  • Provide outdoor combustion air to the appliance that caused the air pressure problem
  • Install a top-sealing damper that’s controlled by a metal chain

#2 – Excess Creosote & Soot

When you have your chimney swept, we are removing any excess creosote that has built up inside your chimney. 

Not only is it important to keep your chimney in good working condition, but the build-up of creosote can cause your chimney to smell like smoke. 

Creosote is a black, flammable, naturally-occurring by-product of using your chimney. Soot is produced by incomplete combustion. 

There’s no way to prevent creosote buildup. 

But you can drastically reduce the chances of your chimney passing the smokey odors into your home with a regular chimney sweep. 

creosote sweep

#3 – Moisture

Water in your chimney is a huge red flag. 

I say this because, when you have a leak, most of the time your chimney has multiple issues that are allowing water to penetrate into your chimney. 

Water causes mold, mildew, and an overall musty odor. 

The best way to make sure your chimney doesn’t have water in it is to install a cap. Without a cap, you are giving an open invitation to water to come straight in from the top. 

But water can come in straight through bricks that haven’t been waterproofed. Or right in through a crack on the mortar. 

Besides stinking up your house, moisture in your chimney can cause the damper to rust and fail. 

And when the water mixes with creosote, you can face damage to your flue liner.

#4 – Animals: Dead or Alive

Animals are gross.

Especially the kind that can climb into your chimney and start to live there. 

Unfortunately for these animals squatter rights don’t apply to them. 

Not only does a good chimney cap keep water out, it will also keep all sorts of pests and rodents out of your chimney. 

It’s not uncommon for animals like raccoons, birds, and snakes to get into your home through your chimney. What’s more is that once they are in  your chimney, it’s unlikely that they’ll be able to find their way out. 

So they end up dying in there, leaving a decomposing body that’s going to stink up the place. 

I can’t have a section about animals in a chimney without mentioning chimney swifts. 

Chimney swifts are small migratory birds that burrow into chimneys to lay their eggs. Depending on the size of your chimney, this could mean thousands of chimney swifts. 

The worst part about chimney swifts is that they are Federally protected. So no one can do anything with them, their nests, or their eggs without risking a federal penalty. 

You just have to wait for them to fly away.

creosote sweep

Final Thoughts

At Patriot Chimney, we’re in the business of keeping your family safe so that you can enjoy your fireplace. 

A big part of that comes from having a regular chimney inspection. We will check top to bottom, and inside out to make sure your chimney is safe to use. 

Plus, we’ll do everything within our powers keep your chimney from passing any odors into your home. 

Fill out the form below or simply give us a call at 540-225-2626 to set up an appointment. 


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