How to Plug a Chimney

Written by j. johnson
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How to Plug a Chimney
A chimney should be plugged if it's no longer being used. (Hemera Technologies/ Images)

A chimney is usually connected to the outside of your home and used to vent smoke that is created by a fireplace below it. If you no longer use the fireplace or the chimney, then you might choose to plug it up, either permanently, or just temporarily during the off season to help improve the energy efficiency of your home. While most of the process will stay the same, whether you want the plug to be permanent or not, the decision to use caulk or weatherstripping will affect the ease of opening the chimney back up.

Skill level:

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Things you need

  • Chimney cap
  • Caulk
  • Tape measure
  • Foam insulation
  • Weatherstripping tape

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  1. 1

    Install a cap on the top of the chimney outside your home. Be sure the cap you order will fit the dimensions of your chimney perfectly. You should not seal the cap to be airtight because this does not allow proper ventilation of the space within. However, while the cap is designed to connect with the flue of the chimney, most caps also come with securing devices, such as anchors, screws, or caulk to hold it in place. If not, you can secure the cap around the chimney with a piece of wire.

  2. 2

    Close the damper on your chimney. The damper is what allows air and smoke to be released outside when the fireplace beneath the chimney is being used. Seal around the damper with caulk for a permanent closure or weatherstripping, if you are closing it for the season.

  3. 3

    Measure the space above your fireplace that leads to the rest of the chimney and eventually outside.

  4. 4

    Cut a piece of foam insulation to fit the space perfectly.

  5. 5

    Push the foam insulation up inside the chimney to completely block off the space.

  6. 6

    Seal around the foam insulation using the caulk if you want a permanent plug. You can also opt for weatherstripping tape instead if you think you might want to unplug the chimney at any point in time.

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