Earthquake Mitigation Measures: How to Protect an Existing Home

Your house is already built, but can you still make it safer during an earthquake? Yes. Earthquake mitigation measures can strengthen your existing home and reduce the risk of damage without requiring a complete rebuild.

Many older homes have weak points, including poor foundation connections, unbraced crawlspace walls, and large garage openings. Targeted improvements can address many of these vulnerabilities.

This guide explains how to protect buildings from earthquakes, including structural upgrades, simple indoor safety measures, retrofit options, and steps you can take to make your home safer.

Why Existing Homes Need Seismic Mitigation

Many older homes were built before today’s earthquake safety standards, and even if your house looks strong, it can have structural weaknesses that make it more vulnerable during an earthquake.

Common weak points include:

• Unbolted foundations: Your house may slide or shift off its foundation during strong shaking.
• Unbraced cripple walls: Short wooden walls beneath your first floor can collapse without proper bracing.
• Soft-story garages: Large garage openings can leave the upper floors without enough support during an earthquake.
• Unreinforced masonry chimneys: Older brick chimneys can crack or collapse during shaking.
• Unsecured utilities: Unstrapped water heaters and rigid gas connections can increase the risk of leaks, fires, and damage.

Seismic mitigation helps address these weaknesses through targeted improvements. Retrofitting can make a home more earthquake-resistant, but it cannot make any house completely earthquake-proof.

Structural Earthquake Mitigation Measures for an Existing Home

Structural earthquake mitigation helps strengthen the parts of your home that resist earthquake shaking. The right improvements depend on your foundation, framing, and existing structural weaknesses.

Here are four important areas to address.

Bolt the House to Its Foundation

Foundation bolting helps keep your house connected to its concrete foundation during an earthquake.

Some older wood frame homes lack adequate foundation bolts, which increases the risk of the house sliding or shifting during strong shaking. A seismic retrofit contractor can install anchor bolts or approved steel foundation plates to strengthen these connections.

Have a professional check your foundation before installation. The type, size, and spacing of the connections must suit your home’s structure, local building requirements, and applicable seismic retrofit guidelines.

Brace Cripple Walls

Cripple walls are short wooden walls between your foundation and first floor. You usually find them in homes with raised foundations and crawlspaces. Without proper bracing, these walls can lean or collapse during earthquake shaking.

Cripple wall bracing involves adding structural plywood panels and strengthening the connections between the walls, floor framing, and foundation. The plywood helps the walls resist sideways forces.

A qualified retrofit company can inspect your crawlspace and determine where bracing and other improvements are needed.

Strengthen Soft Story and Garage Openings

If your home has living space above a garage, the large garage opening may leave too little wall support to resist sideways earthquake forces.

A soft story retrofit can strengthen this area using:

• Steel moment frames around garage openings
• Engineered shear walls
• Stronger connections between structural components

Because these changes affect how your home supports weight and resists shaking, have a structural engineer evaluate the building and design the appropriate improvements.

Address Chimneys and Masonry

Older brick chimneys can crack, separate, or collapse during an earthquake. Falling bricks can also damage your roof or injure someone nearby.

Depending on your chimney’s condition, you may need:

• Engineered bracing to improve stability
• Partial rebuilding of damaged masonry
• Replacement with a lighter chimney or flue system

Earthquake Retrofit Options Compared

Different seismic mitigation measures protect your home against different earthquake risks. The right choice depends on your home’s foundation, structure, and existing weak points.

Here’s a quick comparison of common retrofit options:

Mitigation Measure	What It Protects Against	Typical Home Type	DIY or Professional?	Relative Complexity
Foundation bolting	House sliding off its foundation	Older wood frame homes with raised foundations	Professional recommended	Moderate
Cripple wall bracing	Crawlspace wall collapse	Homes with cripple walls	Professional recommended	Moderate
Soft story retrofit	Collapse of an inadequately supported upper floor	Homes with living space above garages	Structural engineer required	High
Chimney bracing or replacement	Falling masonry and roof damage	Homes with brick chimneys	Professional required	Moderate to high
Water heater strapping	Water heater tipping, damaged connections, and leaks	Homes with tank water heaters	DIY friendly where permitted	Low
Flexible gas connectors or automatic shutoff valves	Gas leaks and related fire risks	Homes with gas service	Licensed professional	Low to moderate

If your home has major structural weaknesses, prioritize those repairs when planning your retrofit. You can also handle simple indoor safety improvements while arranging professional work.

How to Prevent Earthquake Damage Inside Your Home

You can reduce the risk of injuries and damage inside your home by securing items that might fall, tip over, or break during an earthquake.

Here are some practical ways to prevent earthquake damage:

• Secure water heaters: Use seismic straps attached to wall studs or other suitable structural supports.
• Anchor tall furniture: Fasten bookshelves, cabinets, and wardrobes to wall studs to prevent tipping.
• Use flexible connections: Have a qualified professional install approved flexible gas and water connections where needed.
• Secure electronics: Mount televisions and other heavy equipment with suitable brackets or straps.
• Protect wall items: Secure mirrors, artwork, and shelves so they cannot easily fall.
• Install cabinet latches: Keep dishes, chemicals, and other stored items from spilling out.
• Reorganize storage: Place heavy objects on lower shelves, especially in your garage.
• Locate utility shutoffs: Know where to shut off your gas, water, and electricity, and learn when and how to do so safely.

Pay particular attention to tall furniture, glass objects, and heavy appliances near places where your family spends time. These are some of the simple ways to make your home more earthquake-resistant without major structural changes.

DIY vs. Professional Seismic Mitigation

Some earthquake mitigation improvements are simple enough to handle yourself, while others need professional help. You can usually take care of basic tasks such as securing furniture, installing cabinet latches, and fastening household items.

For structural seismic mitigation, hire qualified professionals to handle:

• Foundation bolting and cripple wall bracing
• Soft story and garage retrofits
• Chimney strengthening or replacement
• Gas line modifications

Your city may require permits, engineering plans, or inspections for some of these improvements.

You can also check for local financial assistance. For example, California’s Earthquake Brace + Bolt program offers grants to eligible homeowners when registration and funding are available.

Steps to Start Your Earthquake Mitigation Plan

Start by understanding your home’s structure and identifying the areas that need attention. Here’s how you can plan your earthquake mitigation improvements:

1. Check your home’s construction: Find out when your house was built, what type of foundation it has, and whether it has any previous seismic upgrades.
2. Schedule a seismic assessment: Have a professional inspect your foundation, framing, and other potential weak points.
3. Prioritize structural repairs: Focus on the most serious vulnerabilities based on your inspection results.
4. Handle simple safety tasks: Secure tall furniture, appliances, and other household items that could fall during shaking.
5. Review your emergency preparedness: Check your earthquake insurance, emergency supplies, and family safety plan.

You can also use USGS earthquake hazard information to understand the earthquake risks in your area.

Protect Your Home With the Right Earthquake Mitigation Measures

You can make your existing home safer by addressing its structural weaknesses and securing items inside. The right earthquake mitigation measures can reduce the risk of damage, although no retrofit can eliminate every risk.

Taking action before an earthquake gives you the opportunity to fix problems that could become dangerous during strong shaking.

Not sure where your home is vulnerable? Schedule an earthquake mitigation assessment with Mitigate Now. Our team can inspect your foundation, framing, and key hazards to help you choose the right improvements for your home.

Book Your Seismic Assessment