A fireplace blocker is a removable cover designed to reduce cold drafts and heat loss through an unused fireplace. It typically attaches over the firebox opening or metal surround.

• Magnetic covers/blankets: Attach to steel or iron surrounds and can include insulation for better draft control.
• Insulation blockers/vent covers: Help limit airflow through the opening or louvers when the fireplace isn’t in use.
• Fireplace screens: Mesh or glass-style barriers that help guard against sparks and provide a child/pet barrier; they’re not intended to stop drafts.

Only use blockers on a completely cool fireplace, and remove them before lighting a fire.

One of the simplest options is a magnetic fireplace cover sized to your opening.

1. Confirm material: Magnets stick to steel or iron surrounds (not brick, stone, glass, or aluminum).
2. Clean and dry: Wipe the metal surface so magnets grip well.
3. Center and attach: Align the cover, then press around the edges to reduce gaps.
4. Check coverage: A slight overlap can help limit drafts.

For non-magnetic surrounds, consider a blocker designed for alternative attachment methods or use a free-standing screen for spark protection. Only apply covers to a cool, unused fireplace, and remove before burning.

1. Make sure it’s cool: Wait until the fireplace, doors, and surround are completely cold.
2. Test magnetism: Magnets attach to steel/iron; they won’t stick to masonry or non-ferrous trim.
3. Prep the surface: Wipe off dust and soot so the cover sits flatter.
4. Position the cover: Center it over the opening with a small overlap for better sealing.
5. Press to secure: Smooth from top to bottom and along edges to minimize gaps.
6. Final checks: Ensure no vents or controls are obstructed. Store the cover away from heat when the fireplace is in use.

Remove the cover before lighting a fire.

• Only block when unused: The firebox and surround should be completely cool with no embers.
• Mind appliance type: For gas or vented inserts, follow the manufacturer’s guidance and avoid blocking air inlets or vents; consider consulting a qualified pro.
• Choose suitable materials: Look for covers labeled fire-resistant and intended for fireplaces.
• Maintain access: Don’t cover controls, pilots, or sensors.
• Remove before use: Take off the blocker before lighting any fire or activating a gas unit.
• General home safety: It’s a good idea to keep working smoke and carbon monoxide alarms in your home.

Measure before you shop to help get a better fit.

• Magnetic cover: Measure the width and height of the metal surround or opening. Many customers prefer a cover slightly larger than the opening for overlap. Verify that magnets will sit on metal all around.
• Insulated blankets/blockers: Use the opening’s width/height and allow some overlap to reduce gaps.
• Screens (single or 3-panel): Measure the firebox opening. Choose a screen at least as tall as the opening and wide enough to cover it fully; 3-panel styles should extend past the sides for stability.

Compare your measurements to the item’s listed dimensions on the product page.