Seismic Retrofitting: Why You'll Regret Not Doing It During Your Renovation

Earthquakes are terrifying.
The Noto Peninsula earthquake is still fresh in our memories, but the scary thing is that you never know when or where one will strike.
Everyone might think it won't happen to them, but Kumamoto, which experienced two consecutive magnitude 7 earthquakes ten years ago, was initially considered a safe area with few earthquakes. Considering hidden active faults, a major earthquake could occur anywhere in Japan. That is why we need to be prepared.

You might think that seismic retrofitting costs millions of yen, but if you do it alongside renovation work, it can actually be quite simple to reinforce. To do that, you need to conduct a seismic diagnosis in advance.

Recently, it's easy to calculate on a computer, but it's meaningless if you don't input the data accurately. It's about where the walls are and how strong they are, but entering the building conditions and wall elements accurately can be extremely difficult. Even diagnostic reports created by architectural firms can sometimes contain nonsense. There are also contractors who will perform major renovations without ever mentioning seismic safety.

Reinforcing with good intentions can sometimes actually lower your seismic strength. This is because balance is crucial.

The concept of balance is relatively new and was first explicitly stated in the Building Standards Act, which was revised in 2000 following the Great Hanshin Earthquake. If you reinforce it poorly, you can disrupt the balance and make it weaker, so you should always conduct a seismic diagnosis. Even if it's just for the bathroom, it's better to get it done. There are cases where people finish their renovations, only to look into seismic safety later and find out their home is in terrible shape.

If you had done it during the renovation, it would have only cost a little extra for materials and labor, but sometimes it becomes an irreversible situation.

A key way to identify a reliable contractor is whether they proactively suggest a seismic diagnosis without you having to ask. Contractors who aren't good at it will avoid the topic entirely. It's interesting to have two different companies do it; it's common to get completely different numbers. That's how difficult seismic retrofitting is.

However, it's worth knowing that it's essential if you are renovating. Be especially careful with buildings from before 1981, as they follow even older seismic standards. Recently, even local governments have started prioritizing subsidies for rebuilding over retrofitting.

Even applying for subsidies can be difficult unless you have a contractor who is used to the process.

A building should protect your life, but if you're not careful, it could end up killing you. It might be difficult and confusing, but you should pay more attention to seismic safety, and if possible, installing vibration control devices will give you peace of mind.

I will talk about vibration control devices on another occasion.

If you are concerned about seismic safety, please send me your blueprints and we can think about it together. It's free. If you are currently considering a renovation and are worried about seismic safety, please feel free to consult with me. If you send me your existing blueprints and a simple list of requests, I will create a rough plan with red pen and send it back to you. We can also look at how to interpret a seismic diagnosis together. Of course, it's free, and I ask for no complaints.