How to Secure Chimneys and Fireplaces in an Earthquake

05/03/2023

Why do they matter?

Masonry fireplaces and chimneys in earthquake-prone regions are particularly vulnerable to earthquake damage. Build or retrofit your home with a fireplace and chimney appropriate for an earthquake-prone area.

What do I need to know?

• Unreinforced masonry (URM) chimneys are highly vulnerable to earthquake damage; their behavior is a common consideration of seismic intensity as in the Modified Mercalli Intensity (MMI) scale.   
• Masonry fireplaces and chimneys can be heavy and rigid, and existing chimneys are often brittle.
• Your home and the fireplace and chimney may have significantly different responses to earthquake ground motions, creating the potential for damage to both the house and the fireplace and chimney. 
• Even without signs of damage from an earthquake, the masonry or flue liner may have cracked, so it is vital to have them inspected before reuse.
• Factory-built fireplaces and flues within light-frame fireplace enclosures and chimneys can be used due to their typically good performance during earthquakes. However, you must pay special attention to the detailing of framing anchorage and adhere to the installation instructions specifications for combustible wood framing clearances. 
• Restoring the outside surface of deteriorated mortar joints (repointing) or patching isolated masonry cracks are aesthetic repairs and regular chimney maintenance. However, they are insufficient reinforcement to increase performance during an earthquake. 

Where do I start?

• Constructing or retrofitting a chimney and fireplace requires expertise, so a licensed contractor should perform this type of work to ensure it is done safely and meets the building code requirements.

More Resources:

FEMA 232, Homebuilders’ Guide to Earthquake Resistant Design and Construction

FEMA. Repair of Earthquake-Damaged Masonry Fireplace Chimneys: South Napa Earthquake Recovery Advisory.