Diamond Certified Companies are Rated Highest in Quality and Helpful Expertise.

  • Why this rating is the most accurate.
  • Our editors gather deep company info.
  • Performance is Guaranteed.

Diamond certified companies are top rated and guaranteed

Why Trust Diamond Certified Earthquake Retrofitting Companies Rated Highest in Quality?

By augmenting structural stability, earthquake retrofitting represents a proactive step for safeguarding your home investment. You can feel confident choosing an earthquake retrofitting company listed above because each has been rated Highest in Quality and has earned Diamond Certified. For more information on how best to choose and work with a retrofitting contractor in Marin County, read the following articles. Photo: BB & B Builders Inc (2014)

You are the customer. If your goal is to choose an earthquake retrofitting company that will deliver high customer satisfaction and quality, you’ll feel confident in choosing a Diamond Certified seismic retrofitting contractor. Each has been rated Highest in Quality in the most accurate ratings process anywhere. And you’re always backed by the Diamond Certified Performance Guarantee. Here’s why the Diamond Certified ratings and certification process will help you find a top-rated earthquake retrofitting contractor and is unparalleled in its accuracy, rigor and usefulness:

1) Accuracy: All research is performed by live telephone interviews that verify only real customers are surveyed, so you'll never be fooled by fake reviews.

2) Statistical Reliability: A large random sample of past customers is surveyed on an ongoing basis so the research results you see truly reflect a Diamond Certified company’s top-rated status.

3) Full Disclosure: By clicking the name of a company above you'll see the exact rating results in charts and read verbatim survey responses as well as researched articles on each qualified company.

4) Guaranteed: Your purchase is backed up with mediation and the Diamond Certified Performance Guarantee, so you can choose with confidence.

Click on the name of a Diamond Certified company above to read ratings results, researched articles and verbatim customer survey responses to help you make an informed decision.

More than 200,000 customers of local companies have been interviewed in live telephone calls, and only companies that score Highest in Quality in customer satisfaction–a 90+ on a 100 scale–as well as pass all of the credential-based ratings earn Diamond Certified. By requiring such a high score to qualify, the Diamond Certified program eliminates mediocre and poorly performing companies. Read detailed information about the ratings and certification process.

Read moreRead less

SELECTED PHOTOS FROM THESE TOP RATED COMPANIES

View Comments
Shares

INDUSTRY INFORMATION AND RESEARCHED ARTICLES BY THE DIAMOND CERTIFIED RESOURCE

  • TOTO

  • Schluter Systems

  • Panasonic

  • Porcelanosa

  • Geberit

storefront seismic retrofitting
slab foundation retrofitting
pier and beam foundation retrofitting
block foundation retrofits
concrete building reinforcement
residential seismic retrofitting
commercial seismic retrofitting
industrial earthquake retrofitting
apartment earthquake retrofitting
bridge seismic retrofits

foundation holdown bracket installation
soft story seismic retrofitting
foundation repair
girder securing
building earthquake proofing
structural engineering services
structural seismic designs
earthquake resistant building services
seismic retrofitting
foundation retrofits
foundation bolting
cripple wall bracing

Almonte
Bel Marin Keys
Belvedere
Belvedere Tiburon
Black Point
Bolinas
Corte Madera
Dillon Beach
Dogtown
Fairfax
Forest Knolls
Greenbrae
Ignacio
Inverness
Kent Woodlands
Kentfield
Lagunitas
Larkspur
Lucas Valley
Marin City
Marinwood
Marshall
Mill Valley
Mission Rafael
Muir Beach
Muir Woods
Nicasio
Novato
Olema
Point Reyes Station
Ross
San Anselmo
San Geronimo
San Marin
San Quentin
San Rafael
Santa Venetia
Sausalito
Sleepy Hollow
Stinson Beach
Strawberry Point
Tamal
Tamalpais Valley
Terra Linda
Tiburon
Tomales
Woodacre

94901
94903
94904
94912
94913
94914
94915
94920
94924
94925
94929
94930
94933
94937
94938
94939
94940
94941
94942
94945
94946
94947
94948
94949
94950
94956
94957
94960
94963
94964
94965
94966
94970
94971
94973
94974
94976
94977
94978
94979

Association of Bay Area Governments (ABAG) (www.abag.ca.gov/)
California Earthquake Authority (CEA) (www.earthquakeauthority.com/)
California Emergency Management Agency (CALEMA) (www.calema.ca.gov/)
Contractors State License Board (CSLB) (www.cslb.ca.gov/)
Department of Conservation (www.conservation.ca.gov/)
Federal Emergency Management Agency (FEMA) (www.fema.gov/)

Know What You Want
As You Decide if you Want Earthquake Retrofitting in Marin County

You want your Marin County house, whether in San Anselmo, San Rafael, Larkspur, Mill Valley, Novato, Kentfield, Marshall, or Sausalito, to be safe, to be a good example of earthquake preparedness. You don’t want to invest in a lot of work that will end up doing no good. It’s a good plan to draw up some basic questions that you can ask yourself. Once you narrow down what you want, you’ll find it easier to work with earthquake retrofitters. It’s ok if you can’t use exactly the right industry term. Just know your house and what you want, and you’ll be able to work together to get what you want.

  1. Do I want a Diamond Certified company that is rated best in quality and backed by the Diamond Certified Guarantee?
  2. What kind of earth does my house sit on? Is it more susceptible to liquefaction?
  3. Do I know of any problems with my foundation or house’s structure, or am I just concerned in general?
  4. Do I just want to satisfy the basics that an insurance company is demanding that I complete before renewing a policy?
  5. Do I live very close to a fault?
  6. Do I live on a hillside? Or do I have a multi-storey home?
  7. When was my house built?
  8. Does my house have a cripple wall (aka pony wall)?
  9. Is my foundation made of concrete or of some other material like stone or masonry?
  10. Does my house have vulnerable features like a chimney or porch that need to be tied to the main house?
Read moreRead less
What To Ask In Person
Ask your Marin County Earthquake Retrofitter in Person

You will probably speak with a Marin County seismic retrofitting specialist either when they come to your house to prepare an estimate, or after the estimate and plans are drawn up, to go over those plans. In either case, take your time so that you understand what is being recommended and the proposed benefit. Your house in Marin County, whether in Larkspur, Mill Valley, Marshall, Tiburon, San Anselmo, Novato, or San Rafael is an investment, and you want to keep it safe. Earthquake retrofitting can also be expensive, so you want to know what you are paying for. It might make sense to draw up a list of questions so that you are sure they are covered, no matter how the conversation goes. Some questions might include:

  1. My house beams are redwood, not Douglas fir-larch. Does the recommendation account for this difference?
  2. My house already is bolted to the foundation. What will these extra bolts provide?
  3. What method of blocking, or connecting the shear wall to the mudsill, are you recommending? Nail blocking, staple blocking, reverse nail blocking, or flush-cut? And why?
  4. There is an uneven number of bolts on the different sides of my house – won’t that make the sides have a different amount of resistance?
  5. What grade of plywood are you recommending? How many plies are you recommending in the plywood?
  6. What kind of lumber are you planning to use for framing the shear wall?
  7. How closely will you be placing the nails in the shear wall plywood?
  8. What kinds of hold-downs are you recommending and are they being used as recommended by the manufacturer?
  9. Do you think the concrete is sound enough to use mechanical anchors? Or will you be using adhesive (epoxy) anchors?
  10. You’ve recommended many enhancements. Can you rank them in order of importance, with safety being my prime consideration?
Read moreRead less
  • What To Ask References
    Questions for References

    It’s best to choose a Diamond Certified earthquake retrofitter because all certified companies have passed an in-depth ratings process that most other companies can’t pass. If you want quality from an earthquake retrofitter in Marin County and the greater Bay Area, you can have confidence choosing a Diamond Certified company. Diamond Certified reports are available online for all certified companies. And you’ll never be fooled by fake reviews. That’s because all research is performed in live telephone interviews of actual customers.

    If you can’t find a Diamond Certified earthquake retrofitter within reach, you’ll have to do some research on your own. If you do, it’s wise to call some references provided by your earthquake retrofitter. Keep in mind, though, that references provided to you by the earthquake retrofitter are not equal in value to the large random sample of customers surveyed during the Diamond Certified ratings process. That’s because references given to customers from companies are cherry-picked instead of randomly selected from all their customers. So the contractors will likely give you a few customers to call that they know are satisfied.

    If you do call references on your own, specifically ask for a list of the company’s 10 most recent customers. This will help avoid them giving you the names of only customers they know were satisfied.

    1. Did the earthquake retrofitters work with engineers or architects, or did they do all the plans themselves?
    2. Did the earthquake retrofitters offer free plans and estimates?
    3. Did the earthquake retrofitters take the time to explain why a certain recommendation was made?
    4. Did you feel confident in their knowledge of current building codes and techniques for resisting earthquakes?
    5. Did your house have the same features as mine – multi-storey, on a hillside, near a stream?
    6. Have you been through an earthquake since the house was retrofit? Did you notice anything?
    7. Was the earthquake retrofitting company a good contractor – delivering estimates on time, arriving on time, working through the day, leaving a clean job site?
    8. Did you notice any problems when you inspected the work – split wood, nails sunk in too deeply so they were not flush with the surface, broken concrete, countersunk bolts and washers?
    9. If you noticed problems, did the earthquake retrofitting company address them politely and immediately?
    10. Did the earthquake retrofitting company not only help you get the building permit, but also help you with the building inspections during the progress of the job?
    Read moreRead less
  • Review Your Options
    To Find and Hire a Good Earthquake Retrofitter in Marin County

    The Diamond Certified symbol has been awarded to companies that scored Highest in Quality in an accurate ratings process.

    Your choice of earthquake retrofitter … So before deciding on the best earthquake retrofitter in Marin County for you, it’s important to consider the following questions.

    1. Is the earthquake retrofitter committed to keeping up with the latest training and recommendations for earthquake retrofitting?
    2.  Is the earthquake retrofitter committed to using the building materials – lumber, fasteners, hold-downs – as specified in the building code, in the plans, and as specified by the manufacturer?
    3. Is the earthquake retrofitter willing to work with an engineer or architect on complex projects? And willing to admit when they need such help?
    4. Does the earthquake retrofitting company specialize in seismic retrofitting?
    5. Does the earthquake preparedness specialist have experience working with your particular type of house?
    6.  Does the earthquake retrofitter have a commitment to delivering quality work that meets or exceeds the building code standards?
    7. Does the earthquake retrofitter have the skills to work with the local housing authority to get the permit to work on the project?
    8. Is the earthquake retrofitter committed to reducing the amount of disruption the job will entail?
    Read moreRead less
  • How To Work With
    Before you Hire a Marin County Earthquake Retrofitter

    You must have a written contract in place before you hire your earthquake retrofitting company in Marin County. The contract should specify what work will be performed, the timeframe for completing the work, what the work will cost. The work and the payment may be tied together – for example, there may be certain milestones when payment is required. Make sure you know what those milestones are. The contract should also list any subcontractors.

    Your contractor may also specify what is not included – you should check this very carefully. The contractor is required to tell you if he or she sees certain things as the work progresses – water leaks, plumbing leaks, termites, wood rot, and other conditions that may affect the work. If the contractor does not report these to you, the contractor may find himself or herself held responsible for them. Look out for exclusions of previously existing conditions that were not uncovered before work started or only uncovered while doing the work. If you change the scope of the contract to include getting these fixed – either out of necessity or because you want to – you should get a change or amendment to the contract written down. The contract may allow a contractor to stop working on the job. Typical scenarios would include stopping the job for non-payment. Make sure you understand the terms under which the contract may be terminated.

    Helping Your Marin County Earthquake Retrofit Go More Smoothly
    You have a role to play in making your Marin County earthquake retrofit go more smoothly. Pay attention and ask questions when the plan is presented so that you know what is going on. Try not to change the plans once the project is underway. It may happen that unforeseen circumstances force a change in the plan. Listen carefully to what your contractor is saying, especially if the contractor has mentioned a pre-existing condition. Try to determine if the pre-existing condition is something that needs to be addressed immediately or whether it can wait. Because something can come up at any time, you should always have someone who can make decisions available to respond to the earthquake retrofitting company. Don’t try to ask your earthquake retrofitter to take on more than he or she is responsible for. If plans from an engineer or architect include carport cover bracing, water heating bracing, chimney bracing, tank bracing or veneer selection, the contractor will carry these out. However, the contractor will not take responsibility for damage from the bracing. And if a contractor draws up the earthquake retrofitting plans, bracing is not part of what the contractor will cover

    Read moreRead less
  • Be a Good Customer
    How Can You Be a Good Earthquake Retrofitting Customer?

    It's the earthquake retrofitter’s responsibility put in quality earthquake retrofitting using the best possible installation techniques. But you play a big part in the success of your earthquake retrofitter, too. Here are a few simple steps you can take to be a good customer when hiring a Marin County earthquake retrofitter.

    • Be clear and upfront with the earthquake retrofitting company. Let them know what you want from your earthquake retrofitting, the long-term outcome you’re expecting and specific ways they can satisfy your expectations.
    • Remember, a friendly smile goes a long way!
    • Before you hire an earthquake retrofitting company in Marin County, restate your expectations and goals, and reiterate to the earthquake retrofitter’s representative your understanding of the agreement. Most problems with local earthquake retrofitting companies occur because of a breakdown in communication. By being clear about your expectations and theirs, you can avoid most conflicts.
    • Ask your earthquake retrofitting company if you should call to check on the progress or if he will call you with updates.
    • Be sure your service representative has a phone number where they can reach you at all times while they’re earthquake retrofitting. The work will move along more smoothly if your earthquake retrofitter can reach you for any necessary updates, questions or work authorizations.
    • When your contractor contacts you, return calls promptly to keep the earthquake retrofitting on schedule.
    • Pay for the earthquake retrofitting work promptly.

    Why would you want to be a good customer? Earthquake retrofitting companies in Marin County appreciate customers who are straightforward, honest and easy to work with. Your good customer behavior sets the tone from your end and creates an environment conducive to a good relationship. Things may very well go smoother and any problems may be more easily resolved.

    Read moreRead less
Check The Work
Use Your Contract to Check Your Marin County Earthquake Retrofitter’s Work

The contract you sign should be a detailed and comprehensive document. It will include the scope of work, when it should be done, and when payments are expected. Whenever you reach a milestone, be sure the work is done properly before paying. Look for the proper grade and type of lumber – much lumber has stamped information on it. Look for proper installation with nails that are not embedded but are flush with the surface. Look for bolts and washers that are not countersunk – that is, the wood around them has to be gouged out so you can access them. Look for split wood or broken concrete – these should not occur. Check the installation to the best of your ability before signing off and paying.

Read moreRead less
Written Warranties
Asking Your Marin County Earthquake Retrofitting Company for Warranties

It’s a common practice for earthquake retrofitters to give a one-year warranty on their workmanship. California state law also requires ten years for property damage due to latent defects, at least three years for property damage from poor workmanship, and four years for patent defects. The law also allows virtually an unlimited time to make claims for personal damages resulting from negligent workmanship.

Read moreRead less
Top 10 Requests
Top Service Requests

Marin County seismic retrofitters help keep houses in good shape during an earthquake. There are a few techniques that are commonly used to make houses in Marin County, whether in San Anselmo, San Rafael, Novato, Larkspur, Mill Valley, Sausalito, Fairfax or Marshall, more stiff and strong. While no one can guarantee an earthquake-proof house, there are some steps you can take.

Shear Transfer Ties
Shear transfer ties can help prevent the floor joists from sliding off the mudsill.

Shear Walls
Shear walls provide stiffness and strength – both of which allow houses to better resist earthquakes. Shear walls should be installed on every level of the building, including the crawl space. Best built from plywood, the shear walls should at least be on the four exterior walls, and should be symmetrically placed. Interior shear walls are necessary when the ceiling or floor span is more than three times longer than its width and when the exterior walls don’t provide enough stiffness and strength.

New Bolts
Modern houses that don’t have a cripple wall have walls that are bolted to the foundation. Over time, these bolts may deteriorate. Bolts may also be installed in holes that are bigger than the bolt, making it possible for the earthquake to cause the bolt to shred the mudsill. Additional bolts can be added to help reinforce the original bolts.

New Foundation Anchors
Foundation anchors act like bolts, securing the mudsill, a big wood plank, to the top of the foundation, which is usually concrete or masonry. The foundation anchors can help prevent a house from sliding off its foundation.

Plans
The earthquake retrofit should be completed based on a set of plans. The plans should show what is going to be installed and where. The plans may be drawn up by a contractor, if the building can be retrofitted using prescription standards. If the building requires more particular retrofitting, the plans will be drawn up by an engineer or architect. The local housing authority determines if the building qualifies for the prescriptive standards.

Permits
All earthquake retrofitting requires a building permit. Your contractor should be able to help you apply for your permit.

Bracing
Non-structural elements in your house can benefit from bracing. Water heaters, tanks for water or propane, and similar elements may be prone to fall over in an earthquake. While you would like these secured, they do not fall under the contractor’s jurisdiction unless the contractor is working from plans drawn up by an engineer or architect who specifies the bracing. The contractor will often claim no liability for any damage resulting from the bracing.

Hold-Downs
Hold-downs are special pieces of equipment that are used to secure shear walls. While you may not ask for them by name, it’s important that they are installed according to manufacturer’s instructions. If they are contorted or improperly installed, they lose their strength. Many hold-downs are manufactured by a company named Simpson.

Moment Frames
A moment frame is a steel reinforcing structure that is used where there is not enough room for a shear wall. An engineer or architect will design the moment frame.

Foundation Work
Sometimes foundation work besides bolts and anchors is required. This may include placing columns near the walls to act as a parallel foundation system, capping existing foundations by covering the foundation wall with concrete, or replacing an existing foundation. Masonry foundations, especially unreinforced masonry foundations, are not recommended in earthquake country.

Read moreRead less
Glossary Of Terms
Glossary of Terms Used By Local Earthquake Retrofitting Contractors

The work of earthquake retrofitting is the world of construction contractors, and not all the words may be familiar to lay people. The glossary below should help you better understand all the terms being thrown about when planning and carrying out your earthquake preparations.

acceleration
Refers to a change in velocity. Earthquakes can change their velocity as the waves travel through the ground.

adhesive anchor
A bolt, or rod, along with the washer and nut that uses a chemical to adhere to the concrete of a foundation.

Also known as: epoxy anchor

anchor tie or bolt
A bolt, or threaded rod, that is used to connect the walls to the floor or roof.

bearing wall
A wall that can support vertical loads.

Also known as: load-bearing wall

connector
A connector is a steel device that holds the pieces of the house frame together. The connector is placed where two pieces of the house frame meet.

crawl space
The crawl space is an area that sits under the house. It has short wood-framed walls that are called pony walls or cripple walls.

cripple walls
A cripple wall is a short wall that sits between the foundation and the first floor. The cripple wall should go around the house's perimeter. The cripple wall sits on top of the foundation. They can be quite high when a house is built on a hillside, but are usually 12- 30 inches. They are very vulnerable to earthquakes.

diaphragm
A roof, floor, or continuous membrane that allows the earthquake forces to be transferred to the shear walls.

earthquake
A motion or vibration in the earth that occurs when the lithosphere releases energy.

Also known as: earthquake preparedness, earthquake preparation

expansion anchor
An expansion anchor is a bolt that is set into a pre-drilled hole, after which its base expands to wedge itself into the concrete. The washer and nut are also part of the assembly.

Also known as: mechanical anchor

fasteners
Fasteners may be nails, bolts, screws, or other devices used to connect framing materials.

floor girder
A beam used for floor joist support.

foundation
The foundation is the wall or slab that a house is placed on. It may be concrete, masonry, stone, etc. Concrete is best for resisting earthquakes.

holddown
A device used to prevent a wall from being lifted up. It is placed at the ends of the shear wall framing.

Also known as: hold-down

joist
A joist is part of a floor system. These wooden pieces sit under the floor boards and support the floor. A rim joist goes along the perimeter of the floor.

lateral forces
Lateral forces are effects from earthquakes that move the house from side to side.

Also known as: horizontal forces

load
A load is the weight of material that has to be supported.

moment-resisting frame
A steel device or frame used to resist lateral forces by improving the joint connection between column and beams.

Also known as: moment frame

mudsill
The mudsill is a wooden plank that sits on top of the foundation. The floor system is attached to the mudsill.

Also known as: wood sill, sill plate

OSB/plywood sheathing
The material used to create the shear wall – OSB is fiber-based material, and plywood is wood-based.

perimeter
The outer sides of the building

pier
A column made of concrete or masonry that supports a beam.

post
A piece of wood deployed vertically to support a load.

rafter
Beams or other devices used to support the roof.

seismic retrofit
Measures taken to improve the building's ability to withstand an earthquake. Especially includes structural stability improvements.

shear stress
Shear stress is a physics concept that says that forces act on a body in opposite directions, but not in the same line. Shear stress will often cause a diagonal or X-shaped crack.

stiffness
Refers to the ability of a structural element or system to resist being deformed.

strength
Refers to the ability to resist the forces applied.

stud
The vertical pieces of the structure forming the walls.

Also known as: framing

unreinforced masonry
Masonry that uses mortar as a bonding agent and combines that with the weight of the masonry material to provide the structural stability. It is not allowed in California because it does poorly in earthquakes. Reinforced masonry has steel added to provide better structural stability.

Also known as: URM

vertical
Refers to something that is perpendicular to the ground.

Read moreRead less
Frequently Asked Questions
FAQ for Earthquake Retrofitting Services

Q: Why choose a Diamond Certified earthquake retrofitting company?
A: Diamond Certified helps you choose an earthquake retrofitting company with confidence by offering a list of top-rated local companies who have passed the country's most in-depth rating process. Only earthquake retrofitting companies rated Highest in Quality earn the prestigious Diamond Certified award. Most companies can't pass the ratings. American Ratings Corporation also monitors every Diamond Certified company with ongoing research and ratings. And your purchase is backed by the Diamond Certified Performance Guarantee. So you'll feel confident choosing a Diamond Certified earthquake retrofitting company.

Q: My house has withstood many minor quakes. Do I really need earthquake retrofitting services?
A: It's a good idea to at least check into retrofitting. The Bay Area is home to several faults, and the closer your house is to a fault, the more damage is likely. In addition, over time, your house could be subject to changes – bolts could rust, water could seep into unexpected places, concrete can get old and less reliable. Earthquake retrofitting by definition should never harm an existing structure – it should only improve its ability to withstand earthquakes.

Q: How much does earthquake retrofitting cost?
A: It's impossible to say how much your retrofit will cost. It depends on your house, the kind of foundation it sits on, whether you are on a hillside or not, how many levels the house has, whether there are huge openings that need extra support, and the like. Some firms quote that a very basic retrofit will cost between four and seven thousand dollars, but this is a very hard figure to rely on. The best thing is to find a company that will give you a free estimate.

Q: If I retrofit my house, I am good to go for any earthquakes?
A: An earthquake retrofit does not make a house earthquake-proof. Nothing can. You should avoid firms that promise to make a house earthquake proof. An earthquake retrofit is designed to make your house better withstand an earthquake without significant damage. It is an investment to avert risk, not a sure thing.

Q: Do I need an engineer or architect to draw up my earthquake retrofit plans?
A: It depends. If you have a fairly straightforward house with no tricky bits, a contractor should be able to draw up plans that follow the prescriptive standard. However, for anything beyond the basic, an architect or engineer should draw up the plans. The local housing authority granting the permit to build will be the one who decides if the house fits the criteria to use the prescriptive standard.

Q: Do I need a permit to retrofit my house for earthquakes?
A: Yes, you need a permit to retrofit your house. Some of the work will be done on the foundation, which needs a permit. Your shear wall also requires a building permit. Your contractor should be able to help you get the required permit. Some cities and areas in the Bay Area will waive permit fees for retrofits, so you should ask about the fees required.

Q: What do you mean there is no retrofit building code?
A: According to the California Earthquake Authority, California has a seismic retrofit code, but it is not mandatory. The code is also limited to addressing simple houses built on flat lands. However, there are building codes, which change frequently. Many building code changes have been made after the Loma Prieta and Northridge quakes. For example, after the Northridge quakes, square washers are required for bolts, since the round ones tended to fail. Your contractor/engineer/architect should be up-to-date on the most recent building codes and apply them.

Q: My foundation is damaged. Can I still have earthquake retrofitting services performed?
A: Typically, if the foundation has a crack that measures less than one-eighth of an inch and does not go all the way through – you cannot see to the other side, it's ok to retrofit the foundation, according to the Association of Bay Area Government's guidelines. Cracks larger than that and other damage may require the foundation to be replaced before the retrofitting is done.

Q: Does my new home really need earthquake retrofitting?
A: Homes built recently will be fine, if the home was built to code, since the current codes include the most recent additions to preventing earthquake damage. However, you should check that the seismic provisions of the code were followed correctly. Sometimes they are skipped or incorrectly completed because they increase the cost of construction, and the contractor may not have known how to perform them. Plywood nailing is especially important to the stiffness and strength of house and is one of the areas that may not have been correctly implemented. If retrofitting is required on a new house, it is usually fairly simple.

Q: Does earthquake retrofitting really work?
A: As mentioned, earthquake retrofitting is a preventive measure, not a guarantee. However, the industry is very fond of the following story. In Santa Cruz, two houses were built about 100 years before the 1989 earthquake. They were built by the same builder with identical construction techniques and materials. Over the years, both houses had been remodeled several times. In 1984, a developer bought both houses. One, he had time to retrofit with shear walls on the cripple walls and by securing the mudsill to the foundation. The other house, he did not have time to retrofit before the 1989 quake. After the quake, the retrofitted house, 210 Elm Street, required $5,000 to repair. The house that had not been retrofitted, 214 Elm Street, broke into four pieces. It took over a quarter of a million dollars to repair 214 Elm St.

Read moreRead less