We have been climbing under houses in Los Angeles for more than 25 years and have seen it all. A key mission of ours at Alpha Structural is to prepare Los Angeles for the Big One and man are they still not prepared. Ask Us Anything.

What's the most terrifying thing you've ever come across?

In 1992 we went out to look at this 3 story home in Playa del Rey. During inspection the house was cracking and actually moving. We had to immediately install shoring to prevent the home from collapsing. The hillside had eroded to the extent that the BOTTOM of the original foundation was exposed - hence the threat of imminent collapse. Here it is

I’m a renter in a building that I think is soft story. Is there a way for me to find out if my building has to be retrofitted and is it safe for me to live there for now?

Definitely! We have created a searchable database that people can use to see if their building has been cited. If you are in Los Angeles you can search soft-story search or, if you are in Santa Monica, you can search Santa Monica soft-story search.

Thanks. What does it cost to do a soft story retrofit on a building in Los Angeles? I want my building to be safe but I’m worried my rent will go up. Do you know if the city is doing anything to protect renters from landlords just passing the cost on to them?

The cost for a retrofit varies a large amount. It can be any where from the low tens of thousands to hundreds of thousands. Here is information on how much of the cost landlords can pass to tenants.

How comprehensive are these databases? I personally have a hard time imagining that the city has sent inspectors to every house.

They are actually pretty comprehensive. The city sent around a team of engineers to look at these structures. We have found though that they were not correct in all instances.

What are the natures of the inaccuracies? I would imagine false negatives would be quite bad.

There were a few apartment owners that called us for soft story retrofitting. The City gave them an Order to Comply. Upon initial assessment we found that their properties were not soft stories and helped them get taken off the list.

How can I tell if the apartment I’m in is at risk of a major failure in a quake? The landlord is DGAF about everything and everyone here. I’ve been trying to get out of this state for a while now for so many reasons. This AMA does not make me feel any better about still being here!

The City of Los Angeles released a list of all of the apartment buildings that have, or are due to, receive an order to comply by the City for earthquake retrofitting. You can search for your building: soft-story search.

I’m impressed the city could even muster this thing up. Will have to check if I’m on there. I guess if I am I can reach out to someone who will force the owner to comply? The images of the Northridge quake are still in my mind anytime people start to talk about quakes, hate it.

There are definitely some things that the City got right, and there are some things that the City got wrong. However, they have a good purpose for what they are doing. If your address is on the list they will have sent a letter to the owner of the property. If you feel the need, you can as well reach out to the city.

Are newer homes any better prepared than older homes? My house was built in 2000, within Los Angeles (Harbor City). I'm wondering what the build codes were at that time and if any were designed to protect from earthquake damage.

Yes, newer homes are far superior to older homes. Building codes were changed in 1996 to protect against earthquakes. This was a direct response to the 1994 Northridge earthquake. If your home was built in 2000 you are in good shape.

What if your home was built in 1996?

You should be fine, assuming you are on a raised foundation (home with a crawl space).

What’s the dumbest thing you have seen?

Someone fully excavated under a house leaving the floors hanging in the air. All foundations were left unsupported and suspended in air. That was probably the dumbest. But we have seen all sorts of weird framing and car jacks used to support houses - we have seen everything.

When was the last “big one” LA experienced?

Not to talk over the expert, but there's a strong case that LA has never really experienced a truly "big one." The biggest big-one involves a San Andreas rupture, which would end up shaking the city for 60-90 seconds. Northridge was less than 10 seconds.

This is a valid argument. Here is a link to an LA Times article demonstrating what the "big one" could do.

Hello! Who does your major source of income come from? Businesses or homeowners? And do you think the state will start to pay for large scale work for earthquake preparedness? If it doesn't already. Thanks!

Great question. Almost all of our work comes directly from homeowners or apartment owners. Currently, the State of California has a program that gives a rebate of up to $3,000 for homeowners completing a voluntary earthquake retrofit. The home must qualify for the rebate which you can learn about on their website. As far as apartment buildings, the City of Los Angeles has a mandate ordering the earthquake retrofit of designated buildings that were identified as likely to fail in a significant earthquake. They allow a portion of the costs associated with the retrofit to be passed to the tenants. I don't know that the government will ever pay for large scale work.

What can people look for on their own and how can they prepare?

How about a building built in the 1940s/1950s, built before materials and code got cheap? What are the tell tale signs of concern?

The telltale signs of concerns would be the following:

Sloping floors Door jamming Window frames no longer in square

Buildings built in the 1940s generally don’t have bolting which can leave your home more susceptible to damage in the event of an earthquake.

Wouldn’t this be caused by wood warping as well?

warping of wood members or "deflection" can cause unevenness of the floors. You have to look at everything in the house. Many times you can see that the home is crooked. Look at this

So, just how far away is LA from being prepared for this so called Big One?

There is a good amount of work to do. Keep in mind, most of the homes in Los Angeles were built before construction techniques really accounted for seismic activity. This applies to both commercial and residential properties.

Hmmm.. That’s a good, No answer... I mean you guys are the structural experts, no? Like, based on the work you do wouldn’t you have a somewhat better view of LA’s actual progress. Maybe % of properties inspected that actually need something done?

Okay, we can break this down a little bit more. To put it in context, there were approx 13k apartment buildings in the City of Los Angeles alone that were identified as likely to fail in a significant earthquake. These are buildings that are 3 units or more. This does not apply to all of the smaller apartment buildings or single family homes that have a living space over a garage - this could easily be another 100k or more properties.

Then we can get the Cities of Santa Monica, Beverly Hills, Pasadena, Burbank and others that have buildings with identical construction that would perform the same as the ones in Los Angeles.

Additionally, single family homes built before the 1940s didn't have bolting which secures the framing of the home to the foundation.

I don't have an exact percent as we don't work for the City of Los Angeles though.

Are houses on concrete slabs or raised foundations better equipped for earthquakes, all else being equal?

With a slab foundation you will find the framing of the home bolted to the slab. This keeps the entire structure moving as one piece during an earthquake.

If you have a raised foundation, an earthquake retrofit would be encouraged as the main cause for concern with an earthquake is the framing of the home sliding off the foundation. This is why "bolting" is important.

My personal home is on a slab and I sleep just fine at night.

I have read some of your "worsts". What are some of the weirdest or strangest things you have seen?

Also, let's say LA was magically completely retrofitted to be in compliance, all by next week. Where would you start working towards then? Who else could really use the help?

Stray dogs, bullet shells, the homeless sleeping, dead animals galore and lots of alcohol - which we have never understood why someone would want to drink on their belly under a house.

After residential is completed, the city would more than likely go for commercial and high rise structures. We will always have preventative measures and new building code to work from. It really depends on the city and it's ability to handle ALL structures.

three questions:

1. My building has a soft-first story, but thankfully the retrofit was completed just before I moved in. Is it probably fair to assume that the rest of the building has been inspected (ex: the remainder of the foundation) for seismic compliance too?
2. How many units do you think we'll lose when the San Andreas unleashes an 8.0 on greater LA? Distinct from buildings that just outright collapse (which I know there will be a lot), I'm also guessing wayyyyy more will get redtagged/be unfit for human habitation after.
3. How many of those hillside homes on stilts are going to go tumbling down into the canyons in the aforementioned earthquake?

1. Soft-story codes require performing a seismic analysis to each side of the subject building, for the open or weak planes. This analysis doesn't the foundation anchoring systems (otherwise known as bolting). This portion is not mandated by any City ordinance (at least at this point).
2. Thats hard to anticipate. Mother nature works in mysterious ways. We can never really anticipate which directions seismic forces will yield (laterally, vertically or both simultaneously).
3. Again, hard to say how many will totally fail, but lets put it this way - the taller the stilt home, the worse off you are.

Do you think Los Angeles is better prepared for the Big One than Portland or Seattle?

All that I can say is that Los Angeles has come a long way with their building codes and are now some of the most robust in the nation. I can't comment on Seattle or Portland as I am not personally familiar with their city standards.

I live in A 100+ year old building (in Boston) and my condo board is spending $7.5M to put a new foundation because the building foundation is not structurally sound. Is this short sighted? Isn’t it better to just tear it down or gut it?

Not knowing the information and the particulars of the building and/or project can make it difficult to say whether it's shortsighted or not. Though, if they thought it was better off being worked on than destroyed, I would say it was off good judgement.

What do you know about multi story un reinforced masonry apartments located along metrorail tunnel lines being damaged by vibration?

We have heard of instances of vibrations causing damages to un-reinforced masonry, specifically brick. In most instances the mortar between the brick is so old it can crumble away. I would suggest that you contact an engineer to go out and do an inspection if there is a specific situation you are concerned about.

Is there a big difference between living in the basin of LA vs on some of the hills? I heard that the basin can 'move' more due to liquefaction but the hills/mountains that run throughout and all over LA can better weather it because house foundations are anchored to the rock. Any truth to that? Also, how to best/most economically deal with this as a homeowner?

This is a really good question. As you can see in the [LA Times article] (http://www.latimes.com/local/lanow/la-me-ln-the-big-one-earthquake-video-20160504-story.html) there is a lot of shaking in the basin. This is also going to be particularly concerning in areas designated as liquefaction zones.

As far as hillsides, some homes do have deepened foundations going into bedrock; however, there are a lot of homes built with shallow piles that do not extend to bedrock. A lot of the work that we do is installing site specific deepened foundations to bedrock - the depths of the foundations are always determined by geotechnical engineers.

For homeowners I would recommend doing an earthquake retrofit if your home is not to current standards. It is highly encourage by civic agencies as well as engineering communities. For questions about your particular home you can always reach out to us and we can further answer specifics based on the location of the home.

Hope that this helps.

Regardless of building type, what would you do if you were inside and the big one hit?

Here is an article by the red cross answering your question.

Do my very best to get out of the building or under a strong beam/support. Luckily the building is retrofitted in this hypothetical!

Have you done any work on high rises? Just wondering if the one I'm living in that was built in 1990 will be ok during an earthquake.

Not yet, but our business is always expanding! Perhaps one day we will venture into that side of things. Here is a decent article that may shed some light on the subject.

We don’t work on high rises- just residential at this time. I assume you have a condo or apartment. It should perform okay but everything becomes relative depending on the size and duration of an earthquake.

That’s for doing an AMA! I’m a home owner in the San Gabriel valley, 57 and 210 area. I’ve got a single story slab foundation track home that was built in 1977. Do you have any experience with homes out this way? If so how well are they built at that time? Is there anything specific I should look out for?

This type of home is common in areas like Glendora, Sam Dimas etc. I would just be on the look out for sloping floors, doors and windows that don’t open properly etc. Also, just as a tip make sure water doesn’t flow toward your property.

Otherwise you should be okay. Your framing should be bolted to the slab. You can look in your garage where the framing meets the concrete and you should see bolts.

What's your opinion of post tension cable, if it's done right?

Post tension or pre tension cables can be fine but not what I would want. Ideally, they would minimize cracking as there aren't joints or have fewer joints. They can also allow the slab to be thinner. The reason I don't want one is that if you have plumbing or other issues with the foundation you need engineers and specialists to handle. Areas such as Texas have this type of construction a lot. Fortunately, they are not too common in Los Angeles but there are some.