How To Insulate Fireplace

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Lighting up a roaring fire in a traditional fireplace is a fantastic way to make a room more cozy and livable when the winter nights draw in and a chill sinks its teeth, but when the fire dies down and the embers fizzle out, that fireplace is anything but warming.

How To Insulate Fireplace

Without the stream of hot air lifting out the chimney, the path is clear for cold drafts to find their way down into your fireplace and into your home, meaning your HVAC system has to work overtime to maintain that sweet spot dialed into your thermostat. 

Consequently, the energy bill goes up, and your bank balance goes down.

But it doesn’t have to be this way.

There are a number of ways you can insulate a fireplace when it’s out of use, so when a cold wind’s a-blowin, you’ll have no way o’ knowin’, and I’m going to break the process down for you right here, right now!

Insulating A Fireplace: What Are Your Options?

There’s no shortage of options when it comes to fireplace insulation, but, as you’re about to find out, each method is suited to particular needs and budgets.

Chimney Balloon

A chimney balloon is exactly what it sounds like, a balloon that you inflate in your chimney to block drafts, and it’s great at that, but there are certain things it’s not so great at.

If your chimney leaks when it rains, for instance, a chimney balloon won’t stop it. Nor will it prevent animals from entering your chimney.

It simply sits below the damper and can be inflated via a tube that runs down through the fireplace and into the room.

It’s a solid design, but not a fantastic long-term solution if you’re hoping to block your fireplace indefinitely.

Much like party balloons, the air will gradually escape, and drafts will find passage into your home via the fireplace.

Furthermore, it’s easy to forget that it’s there when you want to light a fire, which is why I’d always suggest leaving a note to inform and remind those in the house that the fireplace is currently out of use.

Fireplace Doors

Fireplace doors are the most aesthetically pleasing way of insulating your fireplace when not in use.

Companies will design them to your specifications, ensuring a perfect fit and a sleek look, but they have more than mere beauty going for them!

You don’t have to cough a lung up trying to inflate any balloons, and there are no safety concerns to worry about, as it’s very clear when they’re in use and how to prime the fire for lighting.

One issue is that they don’t prevent rainwater from reaching your fireplace, but, on the plus side, in the rare event an animal or insect makes it down your chimney, they won’t be able to go any further.

Fireplace Cover

Fireplace covers are commonly simple draft exclusion blankets that you can string up to block the entire firebox.

They’re affordable, effective, and easy enough to use (magnetic ones are best), but they’re not nearly as nice to look at as tailored fireplace doors.

Still, if you invest in a fireplace cover now, you’ll start saving money on your energy bill that you can eventually use to pay for some attractive, custom-fit fireplace doors.

Insulating Foam

Insulate Fireplace

You can make your own solid fireplace cover by treating some cheap plywood with a couple of layers of insulating foam and securing the edges with some weatherstrip.

If you wanted a more elegant out-of-site solution, you could even cut some board down to size to fit just beneath the damper of your fireplace, but much like the balloon, it’s a good idea to leave some kind of notice to warn future fire starters that it’s there.

Chimney Cap Damper

Why let the cold reach its bony fingers all the way down to your firebox if you can deny it access at its point of entry? Well, with a chimney damper cap, you can do just that.

Unfortunately, though, they are quite expensive, and unless it’s a good fit, it won’t be able to form an airtight seal, so you have to have some super accurate cap measurements to hand.

If you can get the dimensions just right, this is the absolute best way to keep everything on the outside from coming inside.

Wool Flue Blocker

Wool flue blockers are another affordable, user-friendly option.

A simple design, a flue blocker is composed of two wool disks separated by a small gap that becomes a dead air barrier when lodged in your fireplace network.

A handle screws into a central threaded port, giving you plenty of reach to make installation and removal as easy as can be, but if the wool gets wet, it won’t take long for mold to spread.

DIY Plastic Shield

If you’re really pulling on the purse strings, you can get pretty good results simply by taping a sheet of plastic over the opening of your fireplace, but this looks pretty darn scruffy, and it’s an exceedingly temporary solution.

Stone

A stone trimmed to size and sealed around the edges with caulk is another popular option, especially if you’re looking for reliable, long-term draft, animal, and rain exclusion.

This insulator can be tricky to install, and removing it can be quite bothersome as well, but as long as you don’t mind putting in some extra elbow grease, it’s a good choice.

Final Thoughts

I’m confident there’s something here that will satisfy any fireplace owner, no matter what their circumstances are.

The premium options are genuinely the best if you can afford them, but a sheet of plastic and some tape will keep you covered in a pinch, or if you’re looking for something reusable, a flue blocker might be just the ticket.

Whichever option you go for, though you may hear those pesky drafts whistle from the rim of your chimney, they stand zero chance of getting into your home and cranking up your energy bills!