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Comment by Fiahil | Hacker News Reader

I expected something much simpler : bricks, stones, and wood. It's not like we are running low on examples of 1000+ years buildings (https://en.wikipedia.org/wiki/11th_century_in_architecture). These castles, cathedrals, farms, were built to last, so it's appropriate to use them as examples.

We can, however, apply modern technics and materials when they make sense : insulation, windows, waterways... Prefer wood, wool and steel over plastics or composite materials and you're good to go.

On a side note, I'm currently buying a house (old farm) with over 200 years old plain oak carpentry. The thing is absolutely massive and would be unimaginably expensive to build today. With the proper care, it might last another 200 years without issue. Remember, Notre-Dame de Paris used 300 years old trees cut in ~1150 for its roof -before the 2019 fire-. With the proper care it would have still be standing today. I find that to be deeply humbling.

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> We can, however, apply modern technics and materials when they make sense : insulation, windows, waterways...

The article raises an important point that could be a problem when trying to mix old and new build techniques. When talking about brick walls it says:

> One tricky thing with this type of assembly is that while it has performed well historically, it doesn’t necessarily play nice with more modern, energy efficient construction. A solid brick wall was traditionally designed to be exposed on the inside, exposing it to interior heat and allowing it to dry. Adding interior insulation makes the house much more comfortable, but also changes the thermal dynamics, potentially causing freeze/thaw damage in the brick, and allowing moisture to accumulate between the brick and the insulation. This is one of the many details that would need to be worked out for the complete design of the home.

You can't simply build something following the examples of a castle or a cathedral, but then add modern insulation, because the insulation won't allow the masonry to breath and dry to both sides, leading to water damage, mold, rot, ...

At the end of the day, a badly insulated building can be made to last for ages passively by just making it breath, so the temperature and humidity vary with the weather but are kept in check by passive external factors (e.g. the sun shining on a external wall dries it from the outside). While a well insulated building absolutely needs constant mechanical HVAC with fine tuned control. You can have a well insulated building or a passive building, you can't have both (by the way, the "Passive House TM" insulation standard is a complete misnomer, being that mechanical ventilation is its second biggest tenet).

Construction seriously depends on location. However, the simplest solution if you want high insulation factors is to have a second air tight structure with an air gap to your brickwork. Just make sure to properly ventilate that air gap. The same approach can then be used on a slate roof.

Essentially you end up with a home inside a shell. There are several advantages to such structures such a potentially great sound insulation and aesthetics, but it’s not cheap. Having an essentially air tight structure requires a hvac system to match. A combination of heat exchanger, filter, humidity control, and temperature control let you have a very comfortable environment while still benefiting from significant insulation.

>Essentially you end up with a home inside a shell.

Which then works against the headline design goal: a house that lasts for 1000 years. How many times would you need to rip down and replace the interior shell? How much more difficult would be demolition if you can't use large equipment and smash the whole lot flat, but instead doing by hand from inside, carefully avoiding damage to the outside shell?

First it’s the system used in the article in part because it’s easy to modify brick structures. Anyway, it depends on your design goals. For a hypothetical 1,000 year home you could have an inner shell of any long lived material including wood which could last that long inside a dry shell as long as you can avoid insect damage.

That said, the real trick to a 1,000 year home is making something that people want to actually use for the next thousand years to avoid it getting replaced rather than the weather or minimal maintenance issues. Because frankly that’s the real threat, which suggests going for something interesting might beat pure utility. An ideal location might be enough but a hook like artistic frescos, intricate stonework, unusual architecture, famous occupant etc could also get you over the hump until the buildings age inherently becomes a draw.

PS: Don’t forget flexibility needs to be part of the design. Electricity, central heating, phone service, AC, and eventually the internet are all relatively recent inventions. I can only assume plenty more systems are going to become normal in the next 1,000 years.

Mortar holding stones from even Roman times, is still wet in the middle.

Well yes, but the example house doesn't seem to be all that optimized for energy efficiency. Look at the illustration showing a fireplace located at the end of the house. That's going to waste so much heat compared to a centrally located one. So I'm not sure how much attention was paid to energy efficiency here.

I came here looking for a comment like this. A fireplace partially exposed to the exterior (as is common nowadays) is essentially entirely decorative and can actually be a net negative in terms of heating the space. seeing that made me question the practicality of the authors other design choices that I know little about.

A lesson I've been repeatedly learning since buying an old house, is that many design decisions that seem dumb now were actually optimized very well for what was available at the time. It can be a real challenge to try to retrofit modern efficiency and comfort into a home that was designed for constraints and expectations of another time.

We recently replaced our furnace and found the footprint of the original coal-fired "octopus" gravity furnace, and learning about the operation of the old furnace makes the seemingly inadequate ductwork make more sense. Instead of a furnace blower (which hadn't been introduced yet at the time the house was built) the air moved around the house by convection and relied on a temperature differential between the center of the house and the outside walls. Hot air came up a few ducts in the middle of the house, and cold air came down through return ducts on the outside walls.

Unfortunately the chimney was also acting as a radiant heating element, and one of the upstairs bedrooms has become much colder since switching to the higher-efficiency furnace (which scavenges much more heat from the exhaust, and vents out the side of the house). Ultimately I'm sure the much more efficient furnace will be worth it, but there are trade-offs that will need to be addressed.

My pet peeve is when people claim that heavy old cast iron radiators are "always better" than new flimsy steel ones.

Yes those are better for old houses with old insulation or no insulation because then you wanted radiator to keep warm so you can sit close to it and get yourself warm. Where with new thing ones you want to heat up the air so you don't want radiator to be warm but air in well insulated building.

> here with new thing ones you want to heat up the air so you don't want radiator to be warm but air in well insulated building.

This is more complicated than this, and the construction industry has actually gone back and forth on this topic for the past 40 years. A few consideration against your point:

- When you heat air, you dry it up, which can be pretty uncomfortable for the inhabitants.

- Air stratification is a big concern: when you heat air up, it raises up to the ceiling, warming nobody but the spiders in the corners. It's not uncommon to have a multiple Celsius degree difference between floor and ceiling, even in an air-tight room.

- A house cannot be air-tight because you need to bring new air for breathing, but also to avoid excess moisture in wet rooms, which means your precious warmed-up air is being vented away, and you bring cold air from outside instead. There exists sophisticated systems with heat exchangers to collect heat from the outgoing air and warm the incoming air, but those are really expensive and far from ubiquitous.

- Under standard conditions, thermal comfort comes in roughly equal part from the radiative flux (from the walls) and conduction/convection (from the air) one. So you can achieve a similar level of comfort with lower air temperature when you have a warm radiative surface in a room.

At the end of the day, old cast-iron radiators are pretty good from a heating standpoint. (But they have multiple drawbacks, like being really big, and so heavy you can't move them when you want to refresh the room paint, etc. which means that nowadays, people usually prefer underfloor heating instead)

> There exists sophisticated systems with heat exchangers to collect heat from the outgoing air and warm the incoming air, but those are really expensive and far from ubiquitous.

Energy recovery ventilation units are not that expensive and are required by code for new construction here in Ontario as of 2017. Adds some cost to the HVAC of a new build, but not that much.

> Energy recovery ventilation units are not that expensive […] Adds some cost to the HVAC of a new build, but not that much.

I've recently had my (individual) house built, and it was 3-4 times more expensive than a regular system. It's not a prominent part of the entire budget for a house, but the difference still made me chose the regular one. But maybe a significant part of the price difference was just a premium for having the high-end tech, more than a real cost difference for the builder.

> are required by code for new construction here in Ontario as of 2017

Interesting. Even for individual houses? Maybe that's a good idea to make it mandatory, if the premium hypothesis above turned to be true.

I believe the requirement that came in earlier for large apartments and condos, but 2017 was the date for detached homes (sadly by far the most common form of development here)

I’m not a super expert, but I believe HVAC here in new builds is about 20-30k, split fairly evenly between parts and install. ERVs are around 1-2k for parts and another grand or so for installation (and significantly easier when done at build time). It likely helps we have such extreme climate our HVAC costs are already quite high, so an extra $1000 here or there isn’t a big deal.

Places more moderate it could easily be a much bigger percentage of the budget and come with reduced ROI. Right now over night I’m heating about 30C temperature difference and I live in one of the most mild parts of the country. Recovering energy is a big deal, as is capturing moisture to reduce load on the humidifier (evaporating water is far from free).

Thanks for your answer. That's a great reminder that everything building-related depends a lot on the weather of the region things are being built!

Yes that is what I am describing as well - that it is more complicated. I am not saying that new steel radiators are somehow superior.

> It's not like we are running low on examples of 1000+ years buildings (https://en.wikipedia.org/wiki/11th_century_in_architecture). These castles, cathedrals, farms, were built to last, so it's appropriate to use them as examples.

This is an easy place to run in to a survivorship bias problem - pick a random 1000 year old farmhouse. How many farmhouses built exactly the same way didn't last for various reasons? Is the fact that one is still standing due to luck, or was it destined to last 1000 years the day it was built?

It doesn't matter that the others fell, we now know what definitely didn't fall - which is all we need to get to.

It matters if you want 99% of the buildings that you build last 1000 years, rather than 0.001%.

Survivorship bias says to look at all the buildings that failed and why they failed rather than looking at the building that survived. You might imitate build but you will not imitate the environment that allowed this one to survive.

It’s not clear how many of the no longer extant old homes and farms fell down due to design issues, due to neglect, or were pulled down for economic or aesthetic reasons. Most architectural styles go through a process where they stop being made, start getting neglected, most of them get pulled down, and the few remaining ones get lovingly restored as they get old and rare enough to become retro rather than just outdated. This tells us very little about how well they were built, even with survivorship bias in mind, because very few buildings will survive an utter lack of maintenance, and less still if many were torn down for not being stylish enough to command the level of rent that the owner is hoping for.

If you look at that list, almost all of the surviving buildings are churches or religious places. If the goal is to build something that lasts 1000 years, then you need to factor in political and utility questions as well besides fixating on materials.

Your home can have perfect architecture, but if a rich person buys your land after you are gone and decides what you've had sucks, it will just get demolished and replaced with something more modern. That rarely happens with churches.

> That rarely happens with churches.

I agree. If the church didn't survive, they would just build a new one.

I imagine there lie the remains of hundreds of separate cathedrals under one. But you would never say "the church fell down". Rather, "there was an accident and renovations were required".

I see them as a Ship of Theseus, where the most long-lasting examples were determined through a lot of trial and error.

Isn't this a thing with Notre Dame? It's been a while but I remember the opening of Hunchback mentions the rebuilding right?

Many cathedrals have been rebuilt two or three times, and building a bigger church over the top of a smaller one is normal, but there are also plenty that have survived more or less as they are for at least several centuries. (Hell, there's an 11th century church in my home village, and it still has the door on the wrong side because the village itself was moved due to plague).

Straight masonry without rebar lasts essentially forever - think of all those Roman viaducts that are still in use. Water can wear through it eventually if the shape lets it, especially in places with freeze-thaw cycles (so there's a saying that a church will survive as long as there's someone around to clear the gutters). I guess hurricanes would probably do it if you're in a place that gets those. But there's just not a whole lot to go wrong with what's essentially a big lump of stone. (Of course a bare stone building is not particularly comfortable for living in, and you have to be a bit more careful about how you maintain wood or fabric on the inside - but the building shell itself will last as it is)

Ding ding ding. You can make a canvas tent last 1000 years if you have a maintenance team constantly making repairs. This is 100% an issue with human incentives, not construction technology.

The fact that there's still a lot of buildings still standing doesn't mean they were built perfect, it just means their construction has the possibility of lasting a 1000 years. For each of those buildings I bet there were 10 more with the exact same building techniques that are no longer standing.

A 1000 years is a lot of time to go without a fire. I think just because of the fire risk wood is simply out of the question. Well unless you can protect the wood against fire like the OP is doing with the steel.

Considering modern times, I think you would have to go one step further and also consider gas explosions and possibly being bombed as well. Just imagine how many 1000+ yr old buildings must have been in Germany before WW2.

There's another bias here that available materials were very different 1000 years ago.

Designing with WW2 in mind is preparing for the next conflict based on the last one. Climate change will have implications, which tend to come out as fire and flooding. This will impact siting.

There are more old buildings left in Germany than one might first assume. The devastation of WW2 was most concentrated in the major cities, and minor cities and villages often have old centers that survived fully intact. This was a bit surprising at least for me when touring the smaller places.

Ya.

I'm very curious about this kind of stuff. And now especially "activhaus" ideas. Being a software guy, probably from envy.

Ages ago, I started remodeling while my Belgian coworker (working from Belgian) started his new home construction. My house in the USA Pacific Northwest is timber framed with tar shingle roof. Coworker's house, IIRC, was block walls and ceramic roof. My house so temporary, their house built for the centuries. A real home.

In North America, I now find the homesteading and packed earth style homes most compelling. Basically, latest tech Arcosanti. (But with better finances.)

Timber frame and a lightweight roof is superior to block walls and ceramic in any scenario that includes seismic activity, which includes the entire American west coast.

If wood stays dry it will last for centuries. Of course given the climate here you'll need to maintain and eventually re-shingle your roof (In the same region and my 34 year old tar shingle roof sprung a leak a few days ago) but if you do that your house will likely last just as long as your coworker's.

Ceramic shingles are replaced after 40-50 years as well. At least in Germany.

Rammed earth you definitely need to be careful of the humidity and mitigation internal humidity is going to be important. Good technique though for arid/desert climates.

Timber Frame + external insulation with anairtight building envelope is a really good construction method that will be energy efficient and last a long time.

With the right clay mixture, rammed earth can be made more or less waterproof like brick, or you can make actual fired rammed earth bricks. Adding graphene flakes can significantly improve the structural qualities, and added carbon black can increase thermal conductivity (heated flooring) or provide em shielding.

There are lots of materials to play with and mix up for structures.

Arcosanti is a lot of concrete, as I recall.

Ya, no longer ideal. I'm keen to see what replacements people come up with. Like hempcrete, packed earth.

What is behind your thinking that plastic won’t last? Plastic is estimated to take 1000 years to decompose in landfills. Obviously it did not exist millennia ago, but I wouldn’t write it off as not future proof.

I too have a 200 year old house and the sagging mentioned in the article seems inevitable in wood.

Plastics break down in sunlight, becoming brittle and easily broken. They're also basically impossible to repair if they do break. They can also been eaten by rodents.

However plastic is a great material for dark, rodent free places.

“Decompose” being the tail end of the deterioration process, with the usable period being far shorter.

plastic becomes very brittle very quickly (years), and falls apart into tiny bits. it's these tiny bits that (we expect) take forever to decompose.

even if we understood plastic to retain its original qualities over time, it is impossible to speculate about a thousand-year lifetime. it's unusual to come across any plastic a hundred years old, intact or not.

Plastic breaks down in tiny pieces and is almost impossible to repair when broken. It's also very difficult to reuse or recycle when you want to. If your house is still standing after a thousand years, it's also because its habitants were able to remodel it without destroying its materials.

As a matter of fact, the amazing carpentry I was talking about previously is made from "fresh" oak, but a significant part of it was also taken from a previous building (church, farm, stable or monastery). It's doing just fine, apart from a few out-of-place mortises. I tried reusing plastic pipes, once, but that wasn't a great idea. It's fine for a few DIY, though.

Stones, bricks, wood are great mostly because they can be reused, but also because they will continue to look great afterwards.

(Note: You might argue that "your" wood is not easy to reuse as well. This happens because we put nails and screws everywhere and we prefer less-dense wood over heavier ones (pines vs oak))

Wood is flammable, and so it’s kind of out of the question. I’d build out of stone or brick, single story but larger footprint. Then of course ground source heat pump and all electric appliances, and solar nearby..

modern wood construction is more resistant to fire than steel, steel loses its structural strength when it gets hot while wood chars on the outside (becoming fire resistant) and doesn’t lose its strength

I've seen the aftermaths of a few barn fires over the past few years. These were old structures, pre-1950s based on appearance, framed with heavy timbers and clad with wood planks and a steel roof. After the fires, the timber frames were still standing on their stone foundations, charred and black, but there was nothing to be seen of the rest of the structure.

I mean.... Cheap Old Houses had a 1000 year old house for sale not long ago.

There's also plenty of timber buildings that last for millenia.

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