Landlords Reinforce 300-Plus Apartment Buildings with Quake Retrofits; Thousands to Go

Months before the deadline to respond, the owners of hundreds of apartment buildings deemed potentially quake vulnerable have already completed the required retrofit.

It is estimated the city of Los Angeles has more than 13,000 apartment buildings with parking tucked underneath, a space-efficient design popular during the building boom of the 1950s and 60s, before engineers discovered the "soft story" designs could be vulnerable to collapse in a strong earthquake. On the morning of the 1994 Northridge quake, 16 died when the Northridge Meadows apartment building collapsed.

Building codes since the late 1970s mandate stronger framing. Two years ago, the city voted to require retrofitting, and gave property owners a series of deadlines. Proof of compliance or submission of plans is required by the middle of next year; completion of all retrofits before the end of 2023.

So far, the owners of 1,921 buildings have responded, according to Jeff Napier, principal inspector for the Los Angeles Department of Building and safety. Of those, 1,037 have received permits, and on 335 the retrofit work has been completed and approved, Napier said.

"It's not worth waiting when people's lives are at risk," said Jett Wolper, a property manager who has formed his own company, Atlas Retrofit, to assist other properties through the process.

"Once you really look at the issue, why wait?" said Lucy Jones, the renowned seismologist who worked with Los Angeles officials to develop the city's 2015 retrofitting ordinance.

Various means are used to reinforce the soft story and provide shear resistance at the driveway opening, usually involving stronger steel supports and beams, the new framing rooted in a stronger foundation, said Garrett Dahlia, construction manager for the Penhall Company, a design/build contractor now involved with several retrofit projects, including three buildings managed by Wolper in Baldwin Village.

Concerns remain about the cost, and affordability for the owners of smaller buildings. 

Officials have estimated the cost at around $10,000 per apartment unit. Wolper said the retrofits he has seen cost upwards of $60,000, in some cases where only one or two units are built above the parking area.

The retrofitting ordianance also addresses an estimated 1,500 older concrete buildings deemed "non-ductile" and required to add additional reinforcement.

Compared to the soft story apartments, the non-ductile concrete buildings in general are larger, and the retrofitting process is more complicated and expensive, with a final deadline a quarter century away.  

Several concrete buildings failed during the Northridge quake.

Some of the buildings that collapsed Tuesday during Mexico's magnitude 7.1 quake appear to be non-ductile, said Jones.

"When we said these have to be repaired, this is why," Jones said. "They do very badly in earthquakes."