Darden Building Materials


When you’re not using the fireplace, you can seal it to prevent wasted money and energy. Closing off the fireplace offers several benefits, including improved indoor air quality, comfort, and energy conservation. In this article, we’ll discuss different ways of sealing fireplaces.

What Happens When Your Fireplace is Unsealed?

An unsealed fireplace creates drafts, allowing the warm air to escape and the cold air to get in. It increases your energy bills since your heater has to work harder to keep the room warm. Sealing the fireplace incorrectly can also cause moisture to build up around it. The moisture produces a foul odor and causes mold to grow as well. If left unfixed, the moisture and cold air can lead to water damage issues. 

Closing Off Fireplaces Temporarily

You have two options to close off a wood burning fireplace temporarily – buy a fireplace sealer or make one.

Buy a Fireplace Sealer

There are three kinds of fireplace sealers – chimney balloons, rectangular chimney pillows, and fitted covers. Chimney balloons are inflatable seals similar to a balloon. Since it’s available in various sizes, you can easily find one that fits your fireplace. Rectangular chimney pillows, also known as fireplace plugs, fit most fireplaces. Apart from reducing drafts, rectangular chimney pillows reduce debris that may fall down the chimney. For fireplaces with a metal screen, consider buying a decorative cover that attaches to the screen with magnets. This cover is usually fire-resistant and easy to remove when you no longer need it.

DIY Seal

You can make a fireplace seal if you have the skills and time to do so. First, measure the fireplace opening since that’s where you’ll install the damper seal. Next, use the measurements to create a pattern on a piece of cardboard. Cut this pattern and then use it as a template for the seal. You can use insulating foam boards to close off the fireplace temporarily. Use the template to make a DIY foam board seal. Once done, put the foam board under the damper and keep it in place using steel insulation springs.

What if You Want to Seal the Fireplace Permanently?

In case you don’t need the fireplace anymore, you can put foam board insulation underneath the chimney and use a joint sealer or caulk to close it off permanently. But if you prefer long-lasting and more effective results, you’ll have to do more than that. First, you need to clean the fireplace and chimney thoroughly. It’s best to call in a professional to do this for you.

Once you’ve cleared the debris, dust, and dirt, take a look at the chimney pipe and find the chase cap. There should be a roof-like structure next to it that prevents rainwater from getting into the chimney. You have to remove this structure and the pipe attached to it. Once you’re done, seal the hole with a scrap of metal and close the damper.

Measure the existing fireplace opening to determine how many bricks you need to seal the hole. You also need to buy air bricks to let air flow through the opening. Once you have the bricks, place them in a row around 12” from the fireplace opening. You also need to put air bricks between the rows and allow them to set.

Next, apply a thin layer of concrete to the bricks. Make sure you don’t apply anything to the air bricks. Once it is almost dry, use a nail to lightly scratch its surface. Apply a thin coat of plaster to the bricks and once it is dry, you can put a decorative grill to hide the air bricks.

For the final step, cover your fireplace with drywall and paint it to match the room’s color scheme. And that’s it. If you need help with your fireplace, whether it’s installing or sealing one, Darden Building Materials can help. Contact us to request a quote today.