Repair and replacement

Chimney Damper Repair and Replacement

A damper is the door between your fireplace and the outdoors. When it sticks, warps or rusts, you feel it as cold drafts, smell it as soot odors, or find it as water in the firebox.

Book Now Read the guide

On this page

Two kinds of damper
Signs of a damper problem
How we assess it
When repair is enough
Replacement options
If you don't use the fireplace
Limits and what affects the scope
Next step
Questions homeowners ask

Two kinds of damper

We repair and replace throat dampers, and we install top-sealing dampers. Which one fits depends on your fireplace and flue.

Throat damper

Most masonry fireplaces were built with a cast-iron or steel damper just above the firebox, at the throat. You open it with a handle, lever or chain. It's out of the weather, but heat, rust and creosote take a toll. A throat damper is a metal plate against a metal frame, so even a good one doesn't seal tightly.

Top-sealing damper

A top-sealing damper sits at the top of the flue, usually built into a cap, with a gasket that closes against the flue opening. It's operated by a cable that runs down to the firebox. Because it closes at the top, it keeps rain and animals out of the flue when closed and blocks the column of air in the chimney. CSIA notes that a top-mounted damper can reduce unwanted airflow and odors.

Our guide to throat dampers vs. top-sealing dampers compares them in more detail.

Signs of a damper problem

You can feel cold air or hear wind at the fireplace with the damper closed
The handle won't move, or the plate won't open or close fully
Rust flakes or water on the damper or firebox floor
Soot or campfire odors in the room, especially in summer or when the air conditioning runs (see why a fireplace smells)
Daylight visible around a closed damper

Damper stuck closed? Don't light a fire. A closed or partly closed damper sends smoke and carbon monoxide into the room. CSIA advises making sure the damper is fully open before lighting a fire.

How we assess it

We open and close the damper, check how far it travels and how well it seats, and look for warping, cracking, rust and missing parts. We check the damper frame where it meets the masonry, since a loose frame lets air and water around it. Above the damper, we look at the smoke chamber and, with a chimney camera where the flue allows, the flue, because a damper replacement may affect what's possible above it. From the roof, when it's safe, we check the top of the flue for fitting a top-sealing damper.

You get photos and our findings, with repair and replacement options, before any work is scheduled.

If you use gas logs or have an appliance venting through the same chimney, we check how the damper has been set up for it, since that affects which options are allowed.

When repair is enough

Some damper problems are mechanical and fixable:

Cleaning soot and rust from the hinge and frame so the plate moves freely
Replacing a broken handle, linkage or pivot
Adjusting a plate that's slipped out of alignment
Replacing a worn gasket or cable on a top-sealing damper

Repair makes sense when the plate and frame are still flat and solid. A warped, cracked or rusted-through throat damper usually can't be made to seal again.

Replacement options

Option	When it fits	Trade-offs
Replace the throat damper with a new one	The frame opening is intact and a matching replacement fits	Same sealing limits as the original; access inside the firebox can be tight
Add a top-sealing damper	The throat damper is broken or missing and the flue top can accept one	Tighter seal; doubles as a rain and animal cover; the cable needs to be in reach
Leave the throat open and rely on a top-sealing damper	A failed throat damper that's impractical to replace	Keeps conditioned air from escaping and outside air from dropping down the flue

If your fireplace has a gas log set, there are specific rules about damper position in the gas appliance's installation instructions. We'll go over them for your setup. See gas fireplace service.

If you don't use the fireplace

A fireplace you never use still has an open path to the outdoors. If the damper doesn't seal, warm air leaves in winter, humid air comes in during summer, and the chimney's odors come with it. Many homeowners with unused fireplaces are surprised by how much air they feel at the hearth on a windy day.

Options for an unused fireplace include a tight-sealing top damper, repairing the existing throat damper, or a properly made cover for the opening. Whatever you choose, it has to be clearly removed or opened before anyone lights a fire again. Labeling the fireplace helps, especially if the house is sold. Our guide to caring for a fireplace you never use covers the other things worth checking.

Limits and what affects the scope

Whether a replacement throat damper is available for the opening
Flue size and shape at the top, for a top-sealing damper
Condition of the flue tile a top-sealing damper attaches to
Whether an existing cap has to come off
Odors can also come from creosote or water in the chimney. A new damper alone won't remove them; a cleaning may also be needed.

Next step

If your fireplace is drafty, smelly or stuck, request an assessment. Let us know whether you burn wood, have gas logs, or don't use the fireplace at all. A team member will contact you to confirm a time.

Request a damper assessment

Questions homeowners ask

Is a top-sealing damper better than a throat damper?

It usually seals more tightly and keeps rain and animals out when closed. Whether it suits your chimney depends on the flue top and how you use the fireplace.

Why does my fireplace smell in summer?

Air can be drawn down the chimney past a leaky damper, bringing creosote odors with it, especially in humid weather. Cleaning and a tighter-sealing damper can both help.

Can I close the damper when I have gas logs?

It depends on the gas appliance. Follow the manufacturer's installation instructions, which often require the damper to be fixed open or have a damper clamp. We'll check during the visit.

My damper is rusted shut. What should I do?

Don't light a fire. A closed damper sends smoke and carbon monoxide into the room. Request an assessment so it can be freed or replaced.

Tell us what you're seeing

Send a short description and a photo if you can. A team member will contact you to confirm a time.

Book Now

Sources

CSIA: Frequently asked questions

Guide