Unused Fireplace

How To Insulate a Fireplace When Not in Use

In Home Maintenance by Giovanni ValleLeave a Comment

If your home has a fireplace, it is imperative that it is properly insulated. Fortunately, insulating a fireplace is not necessarily a complicated process and can be accomplished in one of five methods.

Here’s how to insulate your fireplace when not in use:

  1. Plug your fireplace.
  2. Add a fireplace door.
  3. Cap the chimney.
  4. Try a fireplace blanket.
  5. Install a chimney damper.

Many of us think of fireplaces as a source of warmth, and typically they are just that. However, an unused fireplace that is not properly insulated can also contribute to heat loss. The rest of this article will discuss how to properly insulate a fireplace when it’s not in use.

1. Plug Your Fireplace

Fireplace plugs, also called chimney pillows or balloons, function as a double barrier, blocking cold air from entering your home and simultaneously keeping warm air in the home.

Many homeowners choose fireplace plugs because they provide reasonable insulation without making significant changes to the structure of the chimney. They can also be installed and uninstalled without much difficulty.

Fireplace plugs come in different sizes, so they have to fit correctly. When selecting one, take the time to measure your chimney, as an improper fit will not work well. Even when properly fitted, small gaps may remain, leading to some air leakage.

Chimney balloons and other fireplace plugs have some drawbacks. They are not long-term solutions. Over time, the balloon can deflate. The best practice is to re-inflate every three months.

If the fireplace plug deflates, it can loosen enough to fall. Although occasionally it may end up outside the house, having escaped up the chimney, the balloon will usually fall into the fireplace hearth.

2. Add a Fireplace Door

Another excellent option for insulation is a fireplace door. They reduce heat loss when closed by preventing drafts from entering the home through the chimney. The door acts as a barrier at the hearth of the fireplace.

Fireplace doors are made of glass. Beyond that, there are multiple options available. There are three main types of fireplace doors, which are described further below.

  • Cabinet. Also referred to as twin doors. They open like an average kitchen cabinet door, hence the name. They require clearance on both sides to open fully. They do not close as compactly as either style of bifold doors.
  • Tracked bifold. Bifold doors open by folding in half. Tracked bifold doors glide along a track along the door frame, which causes some restriction.
  • Trackless bifold. Trackless bifold doors not only fold in half but also have the ability to open fully.

Polyurethane foam seals any gaps that may be present around the door, so it’s commonly used to install fireplace doors. Additionally, weather stripping can be added if needed. Altogether, fireplace doors and these materials provide excellent insulation.

Functionally, fireplace doors do more than insulate your home when the fireplace is not in use. They are also an added safety measure, specifically for wood-burning fireplaces, as they keep embers within the fireplace box.

3. Cap the Chimney

Chimney caps are yet another method of insulating your chimney when not in use. But, chimney caps functions extend beyond just insulating your chimney. They will not only keep out cold air, but they also keep out the elements like rainwater. Additionally, chimney caps will keep out any pests that occasionally find their way into chimneys.

Some of the most common critters found in chimneys are squirrels, raccoons, and bats. While they may only seem like a nuisance or inconvenience, they can actually settle in and compromise the integrity of your chimney.

There are two types of chimney caps:

  • Spring-loaded
  • Lock-top

Both are meant to fit with an air-tight seal. Regardless of the type, chimney caps keep the cold air out, helping your home retain heat.

Like the chimney pillows, a chimney cap must also be fitted. In order to create the airtight seal, you will need the correct size. Once properly fitted, downward drafts will no longer be an issue.

One benefit of chimney caps is that they can be used when your fireplace is in use. They prevent gusts of wind from blowing ash, embers, and smoke into the home.

Chimney caps vary widely in price, depending on the size and the materials used. Additionally, they will cost $100-$200 to install. While some people install their own chimney cap, most homeowners opt to hire a chimney professional.

4. Try a Fireplace Blanket

A fireplace blanket is very similar to a fireplace cover or door. It acts as a barrier at the fireplace’s hearth; however, they are recommended for brick, wood-burning fireplaces.

Most importantly, fireplace blankets are fire-resistant. They are typically made of carbon fiber and are easily secured to your metal screen at your hearth using magnets. This simple design keeps cold air out and reduces heat loss through the chimney.

Fireplace blankets are easy to find and use. They are carried at many large retail stores and home improvement stores. When your fireplace is in use, the fireplace blanket is easy to fold and store away.

5. Install a Chimney Damper

A chimney damper is essentially a door within the chimney flue that controls airflow. When closed, it keeps the outside air from entering the home and keeps the air inside the home from escaping through the chimney.

The chimney damper is opened and closed via a handle. There are three handle types:

  • Pivot
  • Poker
  • Rotary

When the fireplace is not in use, the closed chimney damper will provide insulation. However, when the fireplace is in use, the chimney damper should always remain open.

Final Thoughts

Fireplaces can let in unwanted outside air. Fortunately, there are methods that can prevent this. Hopefully, this article has offered some helpful advice to keep your home insulated when your fireplace is not in use.


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