It's not that they're planning for complete annihilation from a massive earthquake, but there's bound to be some wear and tear when a relatively large one strikes every few years. Compound that with the absurd humidity and mold problem endemic to pretty much all of coastal Asia (trying to keep your house mold-free is a losing battle after a certain point and it's unavoidable) and the cost and effort of repairs far outweighs the ease of just tearing it down and rebuilding.
In the west, a 20 year old house is considered brand new. In Japan, 20 years old is bordering on junk territory. 30 years is junk and not worth the effort of repairs. You can search online and find 40 year old houses basically selling for pocket change since they're basically considered moldy death traps on the verge of collapse.
Now, though, Western-style homes built to withstand earthquakes are becoming common and they're expected to be a slightly better investment. How these houses fair against mold is something I'm not sure of.
A commenter below mentioned spirits accumulating in a house, but I've never heard of such a thing and it reeks of mysterious orientalism. But most people won't buy a house that someone committed suicide in or was murdered in. "Jikenya" (incident homes) are marked as such and sell for drastically reduced prices, if they can sell them at all.
Worse than, say, the US South? Just make sure you have air and vapour tightness, with a good whole-house dehumidifier and you should be set.
Good building (science) channel from builder in Austin, TX, where humidity is a thing:
Central air conditioning is not a thing in Japan. People install one split duct heat pump per room they expect to inhabit during summer/winter (generally living + bedroom) and only run those when they're in the room and for as few hours as they can (electricity is expensive)
While air conditioning can reduce humidity, if you have good insulation then your your HVAC won't run that often, but things like cooking and bathing will effect humidity levels, and so a separate apparatus is really needed for that. They're not unreasonably sized:
* https://www.youtube.com/watch?v=OKJnP_6uxcg * https://www.youtube.com/watch?v=D3wd2yVwzvE
Though this does depend slightly on air circulation, but a couple of tubes (e.g.) connecting floors would help balance things out.
Japanese companies produce many quality products that deal with indoor air quality:
* https://news.panasonic.com/global/topics/2017/53539.html
There are stand alone units as well:
* http://www.survivingnjapan.com/2012/08/a-guide-to-dehumidifi...
All that said, a proper building envelope is the first thing that needs to be done. Don't know enough JP codes and construction techniques to comment on that though.
It’s bad around the US south, but it’s really far worse in Asia. Few structures are considered permanent.
* https://www.buildingscience.com/documents/insights/bsi-001-t...
Moist areas should not be able to come in contact with cold areas: if they do, you have a problem with thermal bridging, which leads to condensation.
Not sure if this is meant as hyperbole, how do you explain Japanese buildings built during the 7th century still standing today?
https://blog.gaijinpot.com/problem-with-wooden-buildings-in-...
I remember the first year I was in Japan trying to dry my shirts on the line in the rainy season. All of my clothing was cotton based and quite a lot of it got moldy on the line! Most Japanese clothes these days have at least some synthetics in it so that it dries quicker.
It goes so far that there’s apps to check that this is or isn’t the case. But for obvious reasons, the biggest favor goes to buying a new house.
The only place I ever read about this supposedly terrifying mould is on the internet, usually from Americans. What exactly is wrong with mould? Everyone lives in mouldy houses where I live. Going by Americans online, we should all be dead by now (if not from the mould, from touching raw chicken... the other supposed terror).
The biggest thing about mold in our household is clothes. You constantly have to take your clothes out of storage and air them. I've had a fair amount of clothes ruined to mold and that's the biggest problem I deal with.
My sources say that this is a long held artifact of the shinto belief system and culture. This is a clumsy way to state this but they essentially that houses accumulate spirits over time and become “haunted”. Old dwellings are valued less because they are “dirtied” or “burdened” with an accumulated cruft of spiritual... somethingness. Haunting here isn’t a literal translation but it’s the best I can do in a short time. It’s kind of how Marie Kondos whole schitck is about treating your things as if they have “personness” or “the quality and dignity of being actively present and deserving of respect”.
Most people build a new house because that's the dream: to live in exactly the house you want to live in. If you buy an old house, then you are putting up with somebody else's choices. That and the fact that until recently houses weren't built to last. You seriously don't want to live in a house built in the 1950's. It wouldn't even take an earthquake for it to fall down around you and kill you ;-)
Housing standards have improved dramatically over time and the difference between at 10 year old house and a new house was historically stark (well, at least since WWII). These days it's starting to even out and I see the used house market starting to pick up a bit (personally, I even prefer the houses built 10 years ago to the ones they build now -- It seems nobody wants windows in their new houses any more...)
My understanding is that while people in the US pay for housing with 15 or 30 year mortgages... in Japan the 100 year term is the most common. I am not sure if this has any effect on the market, but people certainly don't think "when I grow old, I'll have this big nest egg locked up in home equity". The bank owned the house when they were born, and it owns it when they die.
I guess it’s possible they’ll give that if you ask for it?
It's actually something people talk about when looking at renting a new apartment.