How To Retrofit a Home for an Earthquake

Earthquakes can cause devastating damage to homes, especially in areas that don’t mandate seismic building codes. Retrofitting your house to withstand seismic activity can significantly reduce the risk of structural failure and keep your family safe. Read on for tips about how to assess your home’s vulnerability, how to install an automatic gas shutoff valve, and how to maintain your earthquake-retrofitted home.

How Earthquakes Affect Houses

The ground moves in a linear direction during an earthquake, and your house can continue to move even as the foundation stops. This motion can lead to structural damage, gas leaks, and falling objects within the home. Seismic retrofitting can help homeowners to shelter in place and repair damage after an earthquake.

Assess Your Home’s Vulnerability

Evaluate your home’s seismic resistance before you begin your retrofitting project. Keep the following factors in mind when determining your earthquake preparedness: 

• Age of the building: Homes built before modern building codes were established (typically before the 1980s) may not have outdated materials and construction practices that are less effective at handling earthquakes.
• Existing structural connections: Poor or inadequate connections between your foundation and walls or the walls and the roof can lead to structural failure and should be strengthened.
• Foundation type and condition: Shallow foundations are typically less stable during earthquakes, especially if the soil is weak or unstable. Issues such as cracks, settling, or erosion can also compromise your foundation’s ability to support your building during an earthquake.
• Local geology: Areas with soft soil can amplify seismic waves and lead to more shaking and potential damage. In areas prone to soil liquefaction (where soil loses its strength due to shaking), additional measures may be needed to prevent structural damage.
• Number of stories in the home: Multi-story homes can be more vulnerable to earthquakes due to their height and complexity, though the overall design and construction quality still matter for single-story homes. Multi-story homes must account for lateral forces and ensure that the load is properly distributed. Reinforced concrete, steel framing, and shear walls are often used to improve seismic resistance.

Key Components of Seismic Retrofitting

Retrofitting for an earthquake involves strengthening your home’s ability to withstand lateral forces. Read more below.

Secure the House to the Foundation

Start your retrofitting project by creating a continuous load path from the roof to the foundation. This is a very important step that helps the home to transfer lateral loads from its frame to its foundation. It also reduces the risk of the structure sliding off its base during an earthquake. Follow the steps below to execute this step:

1. Install shear transfer ties from the floor system to the sill plate
2. Connect the sill plate to the foundation using side plates
3. Anchor the side plates to the concrete foundation

Install an Automatic Gas Shutoff Valve

Gas leaks are hazardous during earthquakes, and can even start fires. Install an earthquake-activated gas shutoff valve at the meter by following the steps below.

1. Shut off the gas to the meter
2. Disconnect the gas pipes 
3. Use pipe dope and nipples to thread the gas shutoff valve into the pipes
4. Reconnect the remaining gas pipes to the meter, and turn the gas back on
5. Check for any leaks

Secure Nonstructural Elements

Secure items within the home to keep yourself safe from falling objects and to prevent certain damages. This will also make navigating your home after an earthquake easier. Follow the steps below to safeguard your home:

• Anchor bookcases and heavy furniture to wall studs
• Secure mirrors and large artwork to prevent falling
• Strap water heaters to nearby walls to prevent tipping and pipe damage
• Use museum putty to secure vases, picture frames, and other decorative items

DIY vs. Professional Earthquake Retrofitting

Homeowners can handle some facets of earthquake retrofitting themselves, but others require professional expertise.  Here are the tasks you can complete on your own to improve earthquake readiness:

• Create and maintain an emergency kit: This should include water, nonperishable food, first aid and medications, and supplies such as a flashlight, radio, Swiss army knife, and portable phone charger. You may also want to include important personal documents, cash, blankets or sleeping bags, a tarp, and other survival gear.
• Identify safe spaces within your home for sheltering during an earthquake: Look for spots under a heavy table, desk, or other sturdy piece of furniture that can protect you from falling objects and debris. Otherwise, crouch against an interior wall away from windows, ideally where no heavy objects can fall on you.
• Install flexible connectors on gas appliances: These connectors are designed to accommodate movement and vibration, reducing damage to the gas lines and preventing leaks.

When To Hire a Professional

Seismic retrofitting often involves complex structural assessments and modifications. Consult a licensed professional for the following tasks:

• Engineered solutions for unique home designs
• Foundation work
• Gas line modifications
• Structural evaluations

Cost Considerations for Earthquake Retrofitting

The cost to retrofit your home for earthquake resistance can range from $3,500 to $8,700, depending on your home’s size, its condition, and how much work it needs.* Though this may seem like a substantial investment, it provides invaluable protection for you and your family.

*Cost data in this article sourced from Angi.

Factors Affecting Retrofitting Costs

The variables below influence the overall cost of seismic retrofitting: 

• Foundation type and condition: You’ll pay more if you need more extensive or complex upgrades.
• Home size and complexity: Larger and more complex homes require more materials, labor, and detailed planning, leading to higher costs.
• Local labor and material costs: Your price may be higher or lower depending on rates in your area.
• Permit and inspection fees: Permit and inspection fees vary by location and will add to your total cost.
• Structural modification required: More extensive changes drive up the price.

Potential Savings and Incentives

Some areas offer incentives for homeowners to retrofit their houses for earthquake resistance. Check with local authorities and insurance providers to see if the following programs are available to you:

• Grant programs for qualifying homeowners
• Insurance premium discounts
• Tax credits or deductions

How To Maintain Your Earthquake-Retrofitted Home

Properly maintaining your retrofitted home can keep you and your family safe during seismic events. Consider the tips below. 

Regular Inspections

Check up on your home’s retrofitted elements annually. The inspection should include these tasks:

• Check that furniture and decorative items remain securely fastened to their respective anchors
• Examine foundation connections for signs of corrosion or loosening
• Inspect straps and anchors on water heaters and large appliances
• Test the automatic gas shutoff valve to make sure it’s functioning properly

Update Your Earthquake Preparedness Plan

Retrofitting your home is just one part of successful earthquake preparedness. Regularly review and update your family’s emergency plan by taking the following preventative measures:

• Practice earthquake drills and evacuation procedures
• Refresh emergency supplies and water storage
• Stay informed about local seismic risks and preparedness resources
• Take a community emergency response training course