Eight-penny common nails. Sheets of five-layer plywood. Wooden blocks. Steel bolts topped with plate washers.
These are the basic components of what it takes to seismically retrofit a wooden-frame, single-family home and make it safer during a major earthquake.
Installed properly, they can prevent walls from shifting and houses from sliding off their foundations and collapsing. They can save lives.
Installed improperly, or only partially, they are little more than a collection of worthless materials that offer minimal to no earthquake protection.
And that’s what the Times frequently found in an investigation of 35 retrofitted houses along the Hayward fault in Oakland, Berkeley, El Cerrito and Albany.
Two veteran building officials who combined have more than 65 years of government experience and who serve on seismic safety boards conducted the inspections for the newspaper.
They concluded that work on 11 of the houses, or less than a third, would probably withstand the shaking of a high-magnitude temblor.
Scientists predict a magnitude 6.7 earthquake is likely to strike the Bay Area before 2032. Yet state and local building codes don’t require specific standards for a safe voluntary seismic retrofit of a home.
To better protect residents, the two inspectors said, California should adopt uniform codes for basic retrofits of single-family homes.
While such standards would be applicable only to homes with relatively simple designs -- say, a typical bungalow or a two-story home with a rectangular or square foundation -- "they would be a start," said Roger Sharpe, one of the Times’ inspectors.
Homes built before 1940 are considered the most vulnerable. Those built between 1940 and 1978 also should be inspected for seismic weaknesses that retrofit work could improve. Building codes for new construction since 1978 have required seismic safety compliance.
In 24 of the 35 of the homes inspected for the Times, residents might have had a false sense of security about earthquake protection, Sharpe and fellow inspector William Schock said.
"This stuff isn’t rocket science. We have identified a problem," Schock said. He is the San Leandro chief building official, president of the California Association of Building Officials and works with the Governor’s Office of Emergency Management on earthquake preparedness.
Despite relatively simple methods and guidelines for successful retrofitting, Schock said, he saw a "lack of fundamental understanding of the principles and materials" within the building community.
As part of their agreement to work with the newspaper, Schock and Sharpe, a retired Walnut Creek building official and member of the Berkeley Disaster Council, would not identify individual contractors or companies.
The state should require additional licensing and training for seismic retrofit contractors, Schock said. "A retrofit contractor has more responsibility than someone doing your kitchen," he said. "There is going be an earthquake. Whole neighborhoods could be uninhabitable."
A spokesman for the California Professional Association of Specialty Contractors, a trade group, said he wasn’t knowledgeable enough about retrofits to comment on Schock’s call for additional licensing.
Some homeowners, such as Fumi Knox, an attorney who lives in Berkeley, were surprised to learn of questionable work.
Schock and Sharpe found bolts in Knox’s foundation without washers and a patchwork of plywood reinforcement inconsistently placed in the basement with a hodgepodge of nails of various sizes. Knox, who bought the house in 2004, said she assumed the work, done in the late 1990s, made her safer.
"I thought it was better than nothing," she said.
It wasn’t. The Times’ inspectors found the work provided her with no safeguards.
Knox hired a structural engineer who concurred with the findings of the Times’ inspectors. "The strengthening does not appear to be well done," the engineer wrote in a report. Knox said she intends to have the house properly retrofitted as soon as possible.
Terry Rossen, another Berkeley resident, said he had "a gut feeling that something was out of whack" when he and the two other owners of a three-unit Berkeley condo paid $7,000 for work on an interior garage wall.
"We probably didn’t get much for $7,000," Rossen said. The Times’ inspectors said they doubted the single interior reinforced wall and foundation bolts would protect the home.
’Making it up’
Like they did with Knox’s house, Schock and Sharpe crept through shallow crawl spaces and navigated cluttered garages and basements to reach the retrofit work.
They crawled across dirt with only a foot or two of head space and wedged themselves between narrow beams to compare the work with retrofit standards widely accepted in the engineering and construction communities -- standards that Schock’s San Leandro department and some other cities recommend to homeowners and contractors.
The deficiencies they routinely found included:
- Nails that were either too small, which can leave connections weak, or too big, which can split critical wood blocks.
- The weakening of reinforced walls, known as shear walls, by driving nails too deeply into plywood.
- Nailing into shear walls that missed the beams behind them.
- Shear walls made of misshapen pieces, or "quilt-works," of plywood rather than the full-size sheets needed to effectively transfer earthquake forces.
- Work done on interior basement walls that should have been done on exterior walls attached to the foundation.
- Shear walls improperly attached to floor joists.
- Brackets designed to prevent hurricane damage are often improperly used to connect shear walls to joists. Stronger brackets specifically designed to transfer earthquake forces between the joists and shear walls are needed.
With no specific code requirements for what constitutes a safe residential retrofit and for which materials should be used, "the contractors appear to be making it up as they go along," Schock said.
"The homeowner needs a standard to work from. The homeowner doesn’t know. They look under the house and see a bunch of shiny hardware and think it’s all OK. It makes sense to have statewide standards," he said.
Schock urged homeowners to educate themselves about seismic retrofits. If work has been done on their homes, they should compare it with standards supported by the Association of Bay Area Governments and, if needed, hire a structural engineer to evaluate their home.
The Times’ findings illustrate "an incredible false sense of security" that exists among homeowners who have paid for retrofit work that gives them less protection than they thinkthey have, said Jeanne Perkins, who runs the Association of Bay Area Governments earthquake program.
A late-1990s association study of retrofit work reached basically the same conclusion, Perkins said.
"There is an expectation that the retrofit will be done appropriately. The permit is signed off on, and they can’t see the work. It’s not like a kitchen or a bathroom. The homeowner doesn’t typically crawl around under their house."
Perkins said there is "an acknowledged need" for code standards and no question that such regulations would enhance public safety. But, she added, "some people see it as a requirement imposed by local government. It is a public policy question."
Building codes are national and international standards that experts establish and that states routinely update through administrative and legislative processes. But the general building code in the United States -- which California uses -- doesn’t address earthquake retrofits
That leaves the state to adopt its own standards.
"It is a very complex process at the state level" to set standards, said Steve Nishimura, executive director of the California Building Standards Commission "State law has to specify it."
There are state standards for the reinforcement of masonry walls, but none that directly addresses home seismic retrofits, said Jim McGowan, the program operations manager of the state Department of Housing and Community Development’s Division of Codes and Standards.
It would take an act of the Legislature for the state body to consider standards, he said, but cities and counties could act independently.
A uniform standard adopted by either the state or governments in earthquake-prone counties would "allow building officials to do the jobs they would like to do," said Tom Tobin, the former executive director of the California Seismic Safety Commission. "And some contractors would love to have the guidance."
Three key elements
Guidance, though, appears to be lacking at most levels.
For example, the state has a 10-year-old law that gives homeowners with earthquake insurance polices a 5 percent discount on premiums if their houses are retrofitted. But the law doesn’t require what engineers and building experts say are the three elements that make a retrofitted home safe.
Without all three of those components -- bolts attaching the home to its foundation; plywood shear walls; and braces that strongly tie those shear walls to the home’s first floor -- an older house would likely suffer major damage in an earthquake.
Still, homeowners frequently hire contractors to bolt their houses to foundations without doing more work. By themselves, the bolts don’t help, but they also don’t make the structure weaker, which is the standard for building work.
"It is ’no harm, no foul,’" Schock said. While building department officials urge homeowners to do more, he said, "we can’t prevent them from doing" partial retrofits.
Because a building permit is issued for the bolting, a homeowner not familiar with retrofit principles might believe the home is safer.
Schock and Sharpe propose a statewide code standard for a single-family home retrofit that requires the three basic elements -- bolts, shear walls and tie-downs -- be shown on plans before building permits are issued.
Included would be details such as nail size, width of plywood and type of tie-down.
A building inspector would later confirm that the work conforms to the plans, Sharpe said.
California’s lack of code standards "makes it the laughingstock of the rest of the nation," said Fred Turner, an engineer with the state Seismic Safety Commission.
Change will likely first occur in earthquake-vulnerable cities, Turner said.
Even the mayor’s house
Berkeley, which offers homeowners a 0.5 percent rebate on the city’s real estate transfer tax if it is applied to retrofit work, might become the first city in the state to adopt retrofit standards.
The proposed Berkeley standards would require contractors to comply with the basic components of earthquake damage prevention to receive a building permit. The standards could be added to the city code later this year.
Mayor Tom Bates wants the city to adopt the rules. He hired a retrofit specialist who found that work on Bates’ 100-year-old home was questionable.
"The foundation wasn’t tied to the shear wall in the front," Bates said in a recent interview. The work’s shortcomings "were clearly visible" said Bates, who crawled under the house with his inspector. "It just isn’t as simple a thing as one thought."
Bates said he also wants the city to find a better way of tracking the work done under its rebate program.
Some homeowners spent the rebate money on partial work and had no other funds to complete the job. When the house is sold again, another rebate opportunity occurs, but there is no city rule to ensure the next round of work finishes what has already been started.
The city needs to ensure contractors aren’t taking advantage of both the rebate program and unsuspecting homeowners by doing needless work that makes nothing safer, Bates said.
"There are instances where people have abused the (rebate program) and put bolts every six inches," he said.
Turner, the Seismic Safety Commission engineer, praised Berkeley for taking the lead on standards. "The state would really benefit from a few pioneer jurisdictions," he said.
Engineers who have studied retrofits, Turner said, are frustrated that public awareness about their benefit continues to lag despite the state’s vulnerability to quakes.
"The thing is, they work in actual earthquakes. That is not disputed," he said.
But they have to be installed properly.
Staff writer John Simerman contributed to this story.
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