fireplace and chimney caulking

Fireplaces and chimneys can be important sources of air leakage. Pay attention joints and openings associated with the chimney and the fireplace (and to home's warm escaping up the chimney). Chimney and fireplace caulking will avoid heat escaping and are crucial for energy savings.

Fireplaces and dampers

When the fireplace is not in use, close its damper. Otherwise, you will lose warm air from the rooms.

Air Sealing Chimneys Make sure that the fireplace damper is tight. To test it close the flue, use a flashlight, light a small piece of paper and investigate the smoke's path. If it goes up the flue, that means that there is an air leak that you should seal by caulking around the damper assembly...

You may use refractory cement for chimney caulking...

See if the damper isn't warped. The damper should fit tightly: if it doesn’t, fix it or have a new one. Sealing Chimney

If you don't use your fireplace, seal it. If you only use it occasionally, make an airtight plug and insert it into the fireplace opening or inside the chimney (rigid board insulation backed by plywood, conveniently sealed at the edges, is a cheap and good solution in such cases).

Images: EERE/Energy Star/DOE

Glass doors and other improvements to fireplaces

Even with their damper closed, traditional fireplaces are energy-inefficient systems, causing a great deal of heat to escape up the chimney.

Glass doors for fireplaces and other improvements do not solve the problem completely. Installing tight-fitting glass doors may help, but just that.

Really good upgrades to old masonry fireplaces include modern fireplace inserts,modern gas stoves, pellet stoves or modern certified wood stoves…. By controlling the airflow through these upgrades you will improve energy efficiency and reduce you energy bills.

See for more details: Fireplaces upgrading

Fireplace Caulking: use a flexible caulk

Check for air leaks around the fireplace, namely where the chimney meets the wall. Remove the trim to inspect and to caulk, if possible or necessary. See if the joint is properly sealed. Caulking materials should be flexible and non-flammable (high-temp).

Openings and cracks around the chimney

Joints, openings and cracks around the chimney should be sealed to avoid air leaks. Use a high-temperature material. Never forget to use high-temp materials in chimney caulking. Do not use flammable materials.

In masonry chimneys, there is often a large gap where the chimney rises through the attic. If this is your case, seal that gap tightly, using a non-flammable material. Also use pieces of sheet metal to fit around the chimney, and seal the chimney joints with a flexible high-temperature caulk.

If you have a factory-built metal chimney do not install insulating materials too close to it, to avoid fire hazards. Keep them at a distance of at least 2’’/50 mm, and install a fire-resistant material around the chimney (a metal enclosure, for instance). Use a high-temperature caulk to avoid chimney air leaks.