What I’m wondering about is who stays on top of older buildings and whether they might be at the point of collapse. I imagine that relevant important public structures have mandated inspections and this is probably not as much of an issue for them. But what about private houses and the like? People buying such houses would get engineers to inspect them, but people living in them don’t. Does it ever happen that such houses simply collapse from long-term structural decay? I never hear about such things happening, although I’ve heard of many instances of people buying houses and inspectors discovering that the house had structural problems and needed to be torn down. So you would think it should be more common for houses to collapse on their long-term occupants, but again I’ve never heard of such a thing that I can recall.
For that matter, how do inspectors inspect structural integrity of houses? Especially if someone has finished their basement, you would think all the key elements would be covered up by studs and sheetrock and there would be nothing to see.
I have never, in my long life , heard of a single building collapsing under its own weight purely out of structural degradation. I have no doubt that the news media would have brought any such event to my attention.
As for any official inspection, I don’t think anything is ever inspected unless it is being involved in some kind of transaction, like being sold, buiding permit, rezoning, of the like. Often, houses are not approved for sale unless certain modifications are brought up to current code, in which case it gets demolished before anything like collapse will take place. For example, the electrical utility will not transfer a service contract on a house where the electrical wiring doea not meet code.
There have been regulations for hundreds of years. I think that it is very rare for a gouse to just collapse without some outside influence like subsidence or, as in this video stupid incompetent builders.
Yes, a structurally sound house even by 100 year old standards will remain structurally sound. Degradation from rot or termites as examples will be noticeable well before a house collapses. Sagging will also be detectable and can be fixed. A lack of structural integrity will be noticeable sooner rather than later, so if any structure has been standing for decades then it’s going to keep standing with reasonable maintenance. There may be a problem in the future with modern engineered materials that were not designed to last forever. We don’t really know how they’ll hold up long term but sudden collapses will still be rare because the indications of problems will appear well before a catastrophe.
Nearly every structure will collapse if left unattended for hundreds of years. I’ve seen the ruins of old stone buildings in woods, some only 300 or 400 years old.
The pyramids not yet, because of shape ( although still deteriorating ), but the oldest buildings on earth — in Europe — much older than they, exist but are very few in number.
I’m thinking that a lot of fasteners will be considerably looser over time. Partially because wood loses its grip as it ages and partially because of vibrations. And there’s also the cumulative impact of various alterations and/or small damages over the years.
But the question, for this and other similar matters is: will it be fixed? I’ve been in a lot of houses with bent/sagging floors, and the owners tend to assume that it’s just par for the course for old houses, and needs to be worked around if you’re doing something like installing a new kitchen, but doesn’t mean the house is about to fall in.
My parents live in an old (100+) house, built pre-sheetrock with plaster on wood slats. When you come up the front (interior) stairs you’re facing a section of wall that it very noticeably curved in towards you. Made me a bit nervous when I was a kid, on the rare occasions that I thought about it, though it’s still standing now. But AFAIK they never contemplated doing anything about it.
Most common is that the roof caves in - typically due to external trigger, like heavy snowfall or winds. Usually, by the time this happens the problem is becoming obvious - leaky roof causes deterioration of trusses and sheathing. By the time it’s close to collapse, it would be uninhabitable. In cities, they building inspectors should catch this. If someone cares to keep the building standing, they will put in the necessary repairs - which should catch failure and either repair or move people out well before catastrophe.
However, coming into downtown Chicago from O’Hare, on the lake side of the train a few stops out of downtown, there appears to be a flat roof that looks like a funnel, it has apparently collapsed in the center. Not sure what the story is behind this. There appeared to (used to be) plenty of abandoned deteriorated buildings in many American cities left to the squatters. Similarly if you go up the Galata tower in Istanbul, you can see nearby a building whose roof is a wreck.
Mostly, you see these collapsed buildings in the countryside, but again, it’s because the occupiers have moved out when repair became too expensive. You have the old homestead building from 1880 and the newer house they built right beside it from 1950 or so.
In the city, the building inspector usually makes someone tear down a deteriorating building because it’s a nuisance and a danger; a number of abandoned buildings become fire traps. Abandoned buildings can be repossessed by the city once taxes are well overdue, and unless it’s a really bad area, someone will want to either repair or replace that building. I suspect a lot of unoccupied buildings in better urban areas are just waiting to be demolished and paperwork is tying up new building permits.
But yes, the walls will usually stay up, especially old 1900 brick walls, long after the wood roof and floors deteriorate to the point of danger.
Most construction methods don’t rely on the fasteners. The exception would be something like steel framing as far as I know.
There’s no question that maintenance is necessary. But construction usually still allows a tremendous amount of deformation before a catastrophic collapse. Your parents old house could be more of a fire hazard than a risk of collapsing if it was built with balloon framing as an example of what to worry about. However it might have built much sturdier than modern construction. That plaster and lath and heavier framing might make it a much stronger structure than the balsa-like framing lumber and sheet rock now used. That curvature in the wall could mean nothing as well based on the exterior construction and might have even been there from the beginning. As you noted in your OP collapses are rare. When houses are deemed unsafe it’s usually because of roof, floor, or foundation problems that would cost too much to repair or can’t be brought up to modern standards without tearing down almost everything anyway.
Now if you go around the world you’ll see lots of substandard construction, generally in impoverished areas. Old style unreinforced masonry construction is idiotic in earthquake zones. And even in this country there are idiots who still construct homes on unstable hillsides, though their house may just slide down the slope intact.
Unless the owners call on someone to check it out there is no overarching agency that proactively examines residential units for structural integrity that I’m aware of. If a contractor is called in to do work they may point out that other work needs to be done to make the house safe. I have no idea if they would contact the local building inspector if they though the building was unsafe. If there was a fire then the building inspectors would examine the unit and might condemn it until specific repairs were made.
In Boston the government agency is Inspectional Services. They handle building, repair, and occupancy permits and usually come into play during renovations, construction, or commercial operations. I don’t see any provisions for calling in a health check on a building you suspect isn’t structurally stable, but you can call your local office and ask them if that’s possible.
I don’t know of any proactive checking of structural integrity from the interior but in Providence they are citing people who have obvious external cracks and damage to homes and buildings. It’s basically a means of raising revenue through fines and permit fees, but in some cases it’s valid.
A properly built structure maintained regularly will last a very, very long time … I think the Hyannis Post Office was built in 1732 and is still in good condition … it’s usually fire or warfare that destroys buildings … they don’t generally just fall down … perhaps a lesson we learned long ago if not knowledge inherited from the Neanderthals …
Are they doing so based on reports by members of the public or are they going around neighborhoods and business districts with municipal employees? Either way, I think this is along the lines of what the OP is looking for.
For post-19th century construction maybe; but the earlier stuff was built properly; sometime last century an old wooden-based beamed house ( lathe & plaster type ), called ‘The Ancient House’ was dismantled from Ipswich and taken over to America for one of those mass exhibitions popular back then. It wasn’t that old, perhaps 15th century; but the dowels were so well made they had to cut the beams loose with saws.
Possibly reassembling with screws.
Meh, the recent Italian earthquake knocked down a lot of old stone houses, but many survived, including a 13th century church. And obviously Rome has a lot of stone building that was ancient when that church was built.
I vaguely think there was a rule-of-thumb: if it fell down in the first 10 years ( and a lot did in Ancient and Mediaeval times [ and even nearer ] ) then the builder was crap, or at the least very unlucky ( like lightning collapsing cathedrals ); for 10 to 100 years, you watched out; after a 100 years it wasn’t going anywhere.
In the 1940s, it was very common to see barns that looked like this
and like this:
Most have been razed. Quite a few were built in a day. It is rare today to see a barn in places where they were once very common, since nearly all suffered a very similar fate, and were torn down because of the high cost or keeping them structurally sound.
There is an adage that a house that is lived in will, by that fact alone, keep it sound, while an abandoned house will deteriorate in a very short time.
They have officials out checking. It’s only what they can see from the street, it is a good idea to check, but they should also send inspectors to check for actual problems not just threaten homeowners with fines for what may only be superficial problems.
Trivia: 2 recent high rise buildings were built wrong and had to be torn down. The one in Seattle had people living in it before they found the problem. In Las Vegas they found the problem before it was being used. They both had structural problems.
On the building conservation side, if a building has been standing for a century, then it’s probably stable, so that the risks you would focus on are long-term material decay in structural members, wind / snow and other loads, and calamities such as foundation movement, groundwater.
Some happen suddenly and catastrophically while others take a while and show telltale signs. The hard part is that there are cracks and cracks. One might be a harbinger of doom while the one right next to it is sloppy plasterwork by the apprentice. That’s where your structural engineer comes in and saves you the big bucks.
