Seismic Retrofit Cost per Sq.Ft.
There are many ways to price earthquake retrofitting. In some cases, the costs are affected by your home’s square footage. Expect to pay $3 to $7 per sq.ft. for total earthquake retrofitting. Some homes may need more or less work, impacting costs. Larger homes are more costly to retrofit, based on more significant square footage and the likelihood of having architectural components that require additional processes for retrofitting. Below are some common square footage home sizes and the estimated seismic retrofit cost.
| Square Footage | Cost to Retrofit (Labor Included) |
|---|
| 1,200 sq.ft. | $3,600 - $8,400 |
| 1,500 sq.ft. | $4,500 - $10,500 |
| 2,000 sq.ft | $6,000 - $14,000 |
| 2,500 sq.ft. | $7,500 - $17,500 |
| 3,000 sq.ft. | $9,000 - $21,000 |
Earthquake Retrofitting Cost by Technique
The strategy your retrofitter employs drastically affects the project cost. While some processes can be used alone, others are used to create more secure support for your home. For example, an earthquake brace and bolt include multiple processes. Below are the most common retrofit techniques and the average cost for that portion for homes between 2,000 and 2,500 sq.ft.
| Retrofit Technique | Cost (Labor Included) |
|---|
| Anchoring to a Mudsill | $1,000 - $2,500 |
| Cripple Wall Bracing | $1,000 - $3,000 |
| Cripple Wall Bolting | $1,000 - $3,000 |
| Foundation Bolting | $1,000 - $5,000 |
| Shear Wall Reinforcement | $3,000 - $6,000 |
Anchoring to a Mudsill
Anchoring your foundation to your mudsill costs $1,000 to $2,500 and is popular with brick foundation homes or homes with crawl spaces. The cripple wall of your home’s crawl space is anchored to the mudsill of your foundation. This is part of the foundation bolting process because the cripple wall and mudsill can slide off the foundation. The mudsill, cripple wall, and foundation need to be bolted for the best stability.
Your mudsill may need to be anchored to a foundation plate, allowing it to support an increased load. URFP are improved foundation plates designed for this and are popular due to their vertical clearance and adjustability.
Cripple Wall Bracing Cost
Cripple wall bracing costs $1,000 and $3,000, depending on the wall size and complexity. Cripple walls are shirt stud walls that enclose a crawl space between the home. They must be reinforced and braced, usually with plywood. Most older cripple walls cannot handle movement during an earthquake, leading to collapse or the home falling off the foundation. Bracing the cripple walls minimizes movement and ensures the home is more secure.
Anchoring a Cripple Wall to the Floor
It costs $1,000 to $3,000 to anchor your cripple wall. The anchoring process includes bolting the wall to the floor above. Bolting it to the foundation is not enough to provide the needed support. The process is done through shear bolting. It may also involve creating a frame on the interior of the cripple wall and bolting this to the wall and floor.
Bolting a House to a Foundation
Expect to pay between $1,000 and $5,000 to bolt your house to your foundation. Anchoring your home directly to the foundation is the bare minimum earthquake retrofitting. It is popular with slab foundations. This helps keep your home from sliding off the foundation and being damaged during an earthquake. This is sometimes called anchor bolting and means that large bolts are sunk through the base of your home and into the foundation.
Shear Wall Reinforcing
It costs between $3,000 and $6,000 to reinforce shear walls during the retrofitting process. The shear walls need extra reinforcement in top-heavy structures, such as an apartment above a garage. This can be done on the upper story’s vertical and horizontal surfaces. Steel grates are commonly used, but this can sometimes be done with additional stud reinforcement on the interior.
Earthquake Retrofitting Cost by Type of Home
Certain homes or aspects of your home increase the earthquake retrofit cost. These retrofits require more labor, alternative methods, or a combination to protect the structure. With these special considerations, the home’s structure makes it more prone to earthquake damage, making retrofitting even more important. Below are homes requiring special retrofitting and the average cost to retrofit each.
| Type of Home | Cost (Labor Included) |
|---|
| Mobile Home | $2,000 - $13,000 |
| Regular Home | $5,000 - $10,000 |
| Hillside House | $7,000 - $20,000 |
| Soft Story | $20,000 - $45,000 |
Mobile Home Earthquake Retrofit Price
Expect to pay between $2,000 and $13,000 to retrofit a 1,000 sq.ft. mobile home for an earthquake. Mobile homes are retrofitted by installing an earthquake-resistant bracing system that ties the mobile home to provide greater support. The most common ways to create this bracing system include anchoring the home with support columns or placing anchors in the ground and fixing them to the home with tie-down strips. In rare cases, the homeowner may add an entire foundation. However, the cost of this is significant. It is uncommon unless the homeowner has other reasons for laying a foundation.
Regular Home Retrofit Price
The average cost to retrofit a regular home of around 2,000 to 2,500 sq.ft. is between $5,000 and $10,000. Retrofitting a regular home is based on the home size and foundation type. Retrofits for a regular house include anchoring to mudsills, supporting cripple walls, reinforcing walls, and bolting the home to the foundation.
Hillside House Retrofit Price
Earthquake retrofitting for a house built on a hillside costs between $7,000 and $20,000. Hillside homes tend to have lateral weakness in their support structures, making the home unsafe in an earthquake. The weakness is often caused by the plywood supporting the home on a stepped foundation. Weakness in the supports leads to significant home damage, sometimes resulting in a total loss. Retrofitting a hillside home involves adding foundation plates and anchors to provide the needed support.
Soft Story Retrofit Cost
One of the most expensive homes to retrofit is a soft story home, costing between $20,000 and $45,000. While a soft story is often found in apartment buildings, some homes have this design. A soft story home typically has a large opening in a space that normally has a wall or structural support. A good example is additional stories over garages. Retrofitting involves reinforcing the area around the garage door or open port so that the walls can support more weight.
Foundation Retrofit Cost by Foundation Type
The foundation your home sits on affects the cost of retrofitting because different supporting structures need to be used based on your foundation. Some foundations require more support than others, and certain foundations require more labor for retrofitting. Below are the most common home foundation types and the average cost for retrofitting each based on a 2,000 to 2,500 sq.ft. home.
| Type of Foundation | Cost (Labor Included) |
|---|
| Slab | $1,000 - $3,000 |
| Brick | $2,000 - $10,000 |
| Basement | $3,000 - $5,000 |
| Post and Pier | $3,000 - $10,000 |
| Footing Stem Wall | $3,500 - $7,200 |
| Thin / Old Concrete | $5,000 - $9,000 |
| Permanent Wood | $5,000 - $10,000 |
Earthquake Retrofit Slab Foundation
Retrofitting a home with a slab foundation costs $1,000 to $3,000. Houses built on slabs do not have crawl spaces or cripple walls that can be reinforced. If your home is newer and was built to code, your house was likely properly bolted and anchored to the slab. If not, a professional retrofitter drills holes in the slab for anchor bolts and fixes straps to complete the retrofit.
Earthquake Retrofit Brick Foundation
If your home has a brick foundation, retrofitting costs from $2,000 to $10,000, depending on the condition of the bricks and mortar. With a brick foundation, the base of the house is a mudsill sitting on the brick. It is this base that is mortared to the brick. Wear, elements, and time lead to weakening, so your professional needs to check the condition before proceeding. The most common retrofitting needs with a brick foundation are anchoring the structure to the mudsill and supporting the crippling wall.
Basement Foundation Retrofit
A retrofit on a home with a basement foundation costs $3,000 to $5,000. Basements are not always common in areas with significant seismic activity, except in older homes. This means many homes with basements must be retrofitted to provide greater stability in an earthquake. Retrofitting a home with a basement requires plywood, bolts, and metal wood connectors to ensure the house is properly connected to the basement and the basement can withstand an earthquake. Top plate ties and mudsill bolting are often part of basement retrofit processes.
Post and Pier Foundation Retrofit Cost
Retrofitting a post and pier foundation costs $3,000 to $10,000. This foundation is often found in older homes and consists of spaced piers with posts. You will not find joists in this foundation but a mudsill or cripple wall. To retrofit this foundation, you need to fix the posts to the pairs using anchoring material, such as T-straps.
Footing and stem wall foundation retrofitting costs $3,500 to $7,200. These houses have a wood-framed base floor on a perimeter foundation made of concrete. When your stem wall home needs to be retrofitted, foundation plates need to be installed beneath the floor, and the floor must be bolted to the plates for greater durability.
Thin / Old Concrete Foundation Retrofit
Retrofitting a home with a thin concrete foundation is a costly retrofit, averaging $5,000 to $9,000. If portions of the concrete are old or too weak, you may be advised to remove or reinforce them before retrofitting. Retrofitting is similar to retrofitting a slab, but plates are likely added to compensate for the thin concrete before bolting.
Permanent Wood Foundation Retrofit
Homes with permanent wood foundations are not designed to withstand an earthquake. Expect to pay $5,000 to $10,000 for retrofitting. In some cases, this retrofit involves replacing portions of the foundation. If replacing the foundation is impossible or too costly, retrofitting involves installing piers and bearing plates into the ground before fixing them to the home.
Labor Cost of Earthquake Retrofitting
Earthquake retrofitting is a specialty construction requiring an earthquake retrofitting contractor or company for the work. The most costly part of earthquake retrofitting is labor, comprising about 70% of the cost, ranging from 60% to 90% of the total project. Total labor for most retrofits costs $2,000 to $8,000, including the initial assessment and plan development. Costs per hour typically run around $50 to $100 per person on the team. Expect a minimum of 2 to 4 people on most jobs. Small jobs may take about 3 to 4 days to complete, while larger jobs may take as long as 1 to 2 weeks.
The percentage you pay in labor depends on the strategy your professionals employ. Bolting is often mostly labor, where installing new sheathing or walls costs more in materials. The labor costs for the projects are warranted because projects take up to a week to complete. In more complicated cases with older homes, it may be beneficial to get an assessment from a seismic retrofit engineer who charges between $100 and $300 for an assessment. An assessment by the retrofit company suffices in most cases.
Cost to Retrofit a House Without Cripple Walls
The cost to retrofit a home without cripple walls costs $1,000 to $2,500 on average. Some homes do not have cripple walls, meaning a lower cost for the project because bracing and bolting this section is unnecessary. However, the joists must be bolted to the mudsill and foundation to prevent the home from sliding. This includes the floor joists, rim joists, and end joists. All must be bolted to the mudsill and foundation to secure the home. Homes without a cripple wall are at more risk for damage than those with them.
Do I Need to Retrofit My Home?
A homeowner may want to retrofit their home for earthquakes for many reasons. If you live in an area with regular earthquake activity, you may consider adding earthquake coverage to your homeowner’s policy. If your home was built before 1980, you might have to retrofit your home to obtain insurance.
Retrofitting your home can prevent your home from foundation replacement, resulting in significant structural damage and high repair costs. Homes built before 1980 should be retrofitted if you live in an area with earthquake activity because your home is likely not secured to the foundation, making it less safe in an earthquake. Retrofitting also provides better financial protection for one of your most valuable assets, your home.
Benefits of Retrofitting
Retrofitting your home offers many benefits if you live in an earthquake-prone area. The biggest is making your home safer. Your home is more likely to sustain damage without retrofitting. Depending on your home’s age and the quake’s severity, a non-retrofitted home could collapse. Retrofitting helps prevent this and lessens the damage severity. This makes it easier to recover after an earthquake and lessens future insurance premiums. Retrofitted homes may also be easier to sell in the future.
Enhancement and Improvement Costs
Reinforce or Strap a Brick Chimney
Reinforcing or strapping a brick chimney costs $2,000 to $8,000, depending on the chimney location and size. If a chimney is not properly reinforced, is damaged, or unsecured, it can lead to more damage to your home in an earthquake. If your chimney falls away, it can lead to costly foundation issues. In many cases, straps are applied to secure the chimney. However, pier installation may be required if it is pulling far away.
Reinforce Masonry Walls
Reinforcement of masonry walls costs between $3,000 and $12,000, depending on the number of walls being reinforced and their size. Weak walls lessen your home’s structural integrity and make it more susceptible to damage during an earthquake. Walls are typically reinforced horizontally and vertically with truss or galvanized steel wire ladder. This material is laid in the mortar in between the blocks or bricks.
Earthquake Gas Shut-Off Valve Installation Cost
Expect to spend between $200 and $500 if you need an earthquake gas shut-off valve installed. Gas lines rupturing are a severe hazard when an earthquake occurs that can lead to significant damage and injury. These valves shut off the gas feeding your home if seismic activity is detected.
Water Heater Bracing
Bracing costs $250 to $400 and can be easily installed by a handyman. If you have a tank-style water heater in your home, you may want to have it strapped to the wall during your retrofit. This bracing helps prevent damage from the tank from coming loose. Water heaters are large and heavy, and they can damage your home, tank, and surrounding pipes in an earthquake. The water heater can be bolted to a stud wall or floor to prevent it from moving.
Seismic Review
A review costs between $200 and $500, depending on the level of detail. If you are unsure of the risk, have a seismic review done of your area to tell you how you may be impacted. However, it can sometimes be impossible to predict damage. Reviews are comprehensive looks at your property, its condition, and what could be done to help prevent damage. You should receive a report with a detailed plan on how to proceed.
Additional Considerations and Costs
- Insurance. Earthquake retrofitting is not usually covered by insurance, but you may qualify for a lower insurance rate once done.
- Licensed professionals. All professionals who work on earthquake retrofitting your home should be licensed and have a permit for the job. Follow up to confirm both.
- Financing. PACE financing may be available to help meet the retrofit costs. This is an affordable financing option available for upgrades that improve efficiency. Criteria change by state, and in some areas, a retrofit could qualify for financing in a larger remodel. Speak to your local municipality for more information.
- Tags. When inspecting homes for earthquake damage, federal, state, and local authorities inspect your home and rate your property’s condition with a tagging system. The system uses red, yellow, and green tags. Red means uninhabitable, and green tags mean safe to live in. Proper retrofitting gives your home a greater likelihood of being green-tagged.
- Additional story. When your home is retrofitted for an earthquake, it is prepared to support its current structure and weight. Adding a floor to your home may require different or additional support. If you plan to add a story to your home, let your retrofit professional know. If your house is already retrofitted and you just added a story, you may need additional support.
- Preparation for earthquakes. To prepare for an earthquake, secure heavy objects and appliances with brackets or straps. Prepare a survival kit with food and medical supplies and keep it in a safe location where you can take shelter during an earthquake. This may be in a doorway or reinforced area.
- DIY. You could undertake some parts of the retrofit if you have carpentry or masonry skills. Most of these projects are best left to the professionals to ensure they are done properly. Some projects that can be done DIY involve bracing large appliances and furniture.
FAQs
Cripple walls are wooden floors and stud walls built on a foundation. These provide additional support for the home and crawl space. Because they are responsible for supporting much of the house’s weight, they can collapse during an earthquake if not properly braced.
- Do I need earthquake insurance?
Deciding on earthquake insurance depends on the area you live in and the financial investment in your home. Earthquakes can cause extensive damage that can be costly to fix. You may be granted disaster assistance in some cases. However, there is usually a cap that is often not enough to cover repairs. If you live in an area with heavy seismic activity, earthquake insurance is likely a good investment.
- How do you tell if your house is bolted to the foundation?
Looking under your house is the best way to check how your foundation is secured. Your house is bolted to the foundation if you see foundation plates connecting to wood or bolts sticking through the plate. If you are unsure, a home inspector can assist.
- What magnitude earthquake can a house withstand?
This depends on many factors, including the home size, location, age, depth and proximity of the earthquake’s epicenter, and if the house has been reinforced or retrofitted. Many existing homes in the United States can withstand earthquakes to a magnitude of 7.0 without significant damage.
- How long does a retrofit take?
Retrofits take a few days to 2 weeks, depending on your home’s age and size and what you have done. Your contractor can give you a better idea of the project length in the initial assessment.
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