How to Block Off Chimney for Gas Logs

It’s the time of year when you want to enjoy your fireplace. You’ve spent hours shopping for the perfect Christmas tree, and now it’s time to snuggle up next to a crackling fire with your family. But there is one problem.

Your chimney has been closed off for gas logs because it wasn’t safe enough or legal to use them in your particular area. If this sounds like your situation, then read on! We’ll teach you how to block off chimney for gas logs so that you can finally enjoy those lovely winter fires in all their glory.

There are several ways you can block off the chimney for gas logs. The most common way is to use a damper clamp which will require drilling into your masonry chimney. Another option is to buy a flexible metal insert that fits inside the flue pipe and blocks off any airflow.

Finally, if you do not want to drill into your brick or stone, metal gaskets are available that fit around the chimney opening and seal up against it with screws.

How to Block Off Chimney for Gas Logs

10 Ways on How to Block Off Chimney for Gas Logs:

So now that you have set up your gas logs, you want to make sure they stay safe. One of the things to keep in mind with these logs is blocking off the chimney vent. After all, there is no need for heat and gas fumes to come out of it when there aren’t any logs burning inside. Here are ten ways to block off a chimney for gas logs.

1. Chimney Cap:

One way to keep animals, insects, leaves and other debris from entering your chimney is to install a cap. Caps are designed to fit snugly on top of the chimney, blocking off the opening and preventing fumes and other unwanted objects from entering your home.

2. Chimney Balloon:

Another way to block off the chimney is with a balloon. You inflate it and set it over the opening to fill the chimney and prevent fumes from escaping. Then, to remove it, you need to pop it! The great thing with this option is that no installation is required, but you are limited with what kind of logs can be used. Also, depending on the type of balloon you get, it can be difficult to put in place and remove.

3. Chimney Cover Plate:

A chimney cover is very similar to a cap but designed differently to fit over the entire opening rather than just the top. They are straightforward to install, but they do take away from the fireplace’s appearance if you have a pretty chimney.

4. Faux fire Screen:

The faux fire screen isn’t just for show – it works well as a way to block off your chimney for gas logs! These screens come in various designs but are all metal and meant to be placed in front of the fireplace opening. However, you can use it for your gas logs by placing it in front of the vent at all times.

5. Damper Clamp:

These clamps are very simple to use; you simply place them over the vent. Once they’re on, it will be hard for even air to pass through. They are perfect if you want easy to install and remove, but keep in mind that there is no way to block fumes from coming up unless you get a clamp with a flap.

6. Professional Chimney Blocking System:

A professional blocking system will give you peace of mind knowing that your vent is properly blocked off. These systems are straightforward to install and come with everything you need, including instructions so you can be sure it is attached correctly.

They are sturdy, won’t rust or corrode, and don’t take away from the look of your fireplace. Plus, they are easy to remove when you want to use your gas logs.

7. Chimney Balloon With Clamp:

10 Ways on How to Block Off Chimney for Gas Logs

If you like the idea of having a balloon blocking off your chimney but would rather have one with an included vent flap, this option is perfect for you! The clamp really helps the balloon stay in place and is easy to remove whenever you want to use your logs.

8. Permanent Fireplace Cover:

Permanent fireplace covers are a great option if you don’t like any of these temporary options and would rather have something that blends better with the look of your home. These covers attach to the fireplace and have a screen over the vent to prevent fumes from escaping. However, ventilation is still possible to keep air circulating if you choose to use your logs. Plus, they are durable enough to be used year after year.

9. Stovepipe Damper:

Stovepipe dampers are another option for blocking off the chimney something more permanent. These covers are made to fit perfectly over your fireplace opening, sealing off the chimney when it is not in use. They are very durable but can make it harder for you to use your gas logs.

10. Permanent Metal Mesh Cover:

If you want something even stronger than a steel metal mesh cover, these covers can do the trick! They attach directly to your fireplace and are designed to keep any fumes from escaping. Of course, you can still use your gas logs with these covers in place, but ventilation will be blocked off for maximum protection against fumes.

Things to Consider Before Blocking off Chimney:

Things to Consider Before Blocking off Chimney

1. Before blocking off the chimney, be sure to remove all ashes.

2. Anyone can do the gas line installation with basic knowledge in this field; however, if you are not confident of your skills in this area, it is recommended that a professional installer be contacted to do the work.

3. A flashing must be installed over the top of the gas log burner to protect against water damage.

4. Failure to follow local building codes may result in fines imposed by your city or county government.

5. Do not attempt this installation unless you are confident and have all the necessary tools on hand; any modifications can lead to leaks, fires, or explosions, causing injury to yourself or others.

6. Be sure to install a shut-off valve as close as possible to the gas line and on both sides of the gas logs before it enters the house (this is a crucial step).

Can You Block a Chimney With a Gas Fire?

If you’re using a gas fireplace, the answer is yes. But only if you block off the chimney properly. There are two parts to this: first, blocking off the firebox so that it doesn’t leak fumes into your home; and second, blocking off all of the vents so that no oxygen gets to the logs.

It would help if you blocked off the firebox using either masonry (mortar or concrete) or metal caulk. If you’re planning to cover it with a decorative material like stone or brick, this part is easy; use the same material to block the gas fireplace’s air leakage. Again, be sure that no mortar gets into the firebox.


If you’re interested in learning more about how to block off chimney for gas logs, be sure to check out our blog post. We’ve got all the information you need including tips and tricks on what not to do when it comes time for installation. With the right knowledge, this process can go smoothly with minimal effort required. Check back often as we will update this page regularly, so stay tuned!

Angela Ervin

Angela Ervin

Angela is the executive editor of DIY quickly. She began her career as an interior designer before applying her strategic and creative passion to lifestyle and home. She has close to 15 years of experience in creative writing and online content strategy for housekeeping, home decorations as well as other niche efforts. She loves her job and has the privilege of working with an extraordinary team. She lives with her husband, two sons, and daughter in Petersburg. When she's not busy working she spent time with her family.

We will be happy to hear your thoughts

Leave a reply

DIY Quickly