In China, people don't believe me that Americans live in wooden houses like they see in movies. Some think it's some kind of a set, or super-conspiracy by the party to render America in a bad light.
A condo I lived in had brick walls between neighbors - definitely a huge plus compared to drywall in apartments where the neighbors can hear you turning on the tv at whisper sound levels.
They were terrible, yet better than a wooden house.
As somebody who spent few years of my childhood in Russia, I find it bizarre that today construction quality actually went lower than that.
Thermal conductivity of materials are telling different story [1]. Polystyrene or mineral wool are good for insulation because they have low thermal conductivity 0.032 - 0.038 W/mK (these values are not exact obviously, you can also find mineral wool with values 0.033 not 0.038 but that is just detail). Timber here is 0.14 - 0.17 W/mK. We can find also concrete with 0.16 which is pretty low for concrete but unfortunately that is just aerated concrete which is different from more dense - reinforced one.
So for example in my home country (in central/eastern Europe) where we have Soviet apartment blocks and decide to insulate them we need to cover them with 30cm thick layer of mineral wool or polystyrene foam in order to meet current standards for thermal resistance. Most of them are already insulated at least decade now (unfortunately with just 10-20cm thin layer).
[1] https://www.designingbuildings.co.uk/wiki/Thermal_conductivi...
Wood will last longer [than reinforced concrete], again, with proper care. But in the end, entropy wins against wood as well. [And again, wood will never outlast the Pyramids].
In civil engineering, there really is no such thing as a free lunch. All materials come with drawbacks.
EDIT: To clarify wording.
Basically rust is the problem, so if you are scrupulous on upkeep (read, spend money) it will last much longer than if not. How long is also enviroment dependents (temperature swings, salt air, emiisions etc. can make it worse)
But if we are comparing concrete and wood as construction material we should use buildings that can be built with either.
I'm curious to understand why as this seems completely counter-intuitive to me (someone with no expertise in materials science or building things!). Can you elaborate?
What does the caveat of "with proper care" actually mean? Isolation from all the elements? Does routine maintenance count (replacing deteriorating materials? replacing fasteners? reinforcing?)?
A wood structure properly taken care of does not seem like it would last longer than a pyramid or a reinforced concrete structure, if each of those is taken proper care of. But this is a hunch, not data, and based on nothing remotely scientific. I'm fascinated by this kind of thing; I appreciate any tidbits you can share!
I meant that wood will last longer than reinforced concrete, even when you are properly caring for both.
Neither will outlast the Pyramids.
I'll reword my comment so that people understand it better.
Wood is simpler, because it isn't a composite material. You have to prevent it from rotting and from being eaten, but on a timescale of a couple decades we can do that quite well. Also with wood structures it's often easier to replace small parts as soon as damage occurs, which prolongs the overall lifetime (similar to steel structures, but unlike reinforced concrete).
There are actually quite a number of ancient temples, churches, bridges, castles, and roads still in use throughout Europe, Asia, and the Middle East. Hōryū-ji [1] in Japan is a 1300-year-old wooden Buddhist temple that's still in use today!
Non-reinforced concrete has to be built bigger, but can last a long time. The coliseum is still up - Hoover Dam will also probably last awhile. And that's without much maintenance.
Smaller non-reinforced structures are harder to build. You have to use the concrete to hold itself up which requires a larger structure.
So you're left with reinforcement. There are options for non-rusting rebar, and non-rusting coatings, but I believe they're expensive. Also, any nick or scratch in a coating ruins it. There's also unique and novel research for non-rebar reinforcement - again expensive.
Here in US most buildings are built to last X years. So long as the rebar lasts longer than X, they'll use rebar. Increase X via regulations, and the quality (and cost) of the buildings in that area increases. Otherwise the bidder with the lowest cost of materials is most competitive. Anyone know what it's like in China?
Galvanised rebar is omnipresent around the world. I believe even mandatory in some countries.
> Otherwise the bidder with the lowest cost of materials is most competitive. Anyone know what it's like in China?
Just as you said. Construction companies save on everything. GFRP rebar got adopted in China not so much because of advantages, but because of code allowing for lower concrete cover with it, as I heard.
The only way to fix it is to remove existing rebar and replace it which isn’t viable on most structures.
Wood construction, on the other hand, is extremely easy to repair. You can cut away sections and replace them piecemeal, essentially forever.
Wood gives you the ability to continuously build a Ship of Theseus, while structurally compromised concrete structures often require you to tear them down and build them again from scratch.
A lot of this discussion is comparing apples to oranges. Reinforced concrete often serves applications that wood is simply unable to perform in (bridges, heavy duty foundations, dams, retaining walls). And yes, poorly maintained, especially prestressed concrete in those applications will deteriorate and fail - but the structure would be impossible with wood in the first place. In more light duty applications wood and concrete can both serve well, but good luck protecting a foundation made of wood from water intrusion. For light duty applications there is no argument that concrete can be overkill and wood can be very appealing.
I agree that wooden houses are not comparable to reinforced concrete bridges. But the part I'm trying to highlight is that being able to easily inspect a structure is a critically important aspect of maintenance, and that most reinforced concrete is inherently difficult or impossible to inspect. The fact that exterior waterproofing is relatively cheap is only incidental.
It's not enough to overengineer a bridge and say it'll last a hundred years if you don't have a reliable way to determine when the bridge is no longer safe beyond year 70. Kicking the can down the road is not a viable long-term strategy. We're about 100 years into widespread use of reinforced concrete and are now starting to see the occasional catastrophic results.
Potting steel in concrete is done because it's cheap and easy, not because it's particularly maintainable. It's inherently difficult to inspect the structure when you build things this way.
> especially prestressed concrete
Agree. Unbonded, post-tensioned concrete (where you can replace individual strands) seems like the only reasonable approach to me, but building this way and doing all of the inspection and maintenance is way more expensive than the "do almost nothing" approach for rebar concrete. But the benefits are only realized after 100 years, so nobody has the incentive to design this way.
I have a hard time believing this. Despite the ridiculous claims of another poster in this thread (that rebar just spontaneously and completely turns into rust) properly formulated and surfaced concrete and steel don't just rot on the inside with no external signs of decay. If you have repeated water intrusion, you will see seeping and cracks. If you have increasing stress, you'll see spalling. You can core concrete, drill out and patch rebar if you have spot damage.
In general I find the sentiments in this thread bizarre since the vast majority of long-lasting buildings now and in the past century are made of concrete (many of the more modern ones have a concrete foundation and wood or steel superstructure). You don't see many old wood structures because most of them decayed and were torn down - there's a reason why you don't see many wooden bridges standing. Concrete is the closest thing that we have structurally to something that can last forever, and we're learning more about how to make it last longer all the time.
Let me know if you have links that discuss maintainability of concrete in this context. Would be glad to learn more.
I believe there is a very unfortunate example of this in Miami in the recent condominium collapse.
A bridge recently collapsed in Italy.
Etc.
So the problem of failing concrete structures is not 'theoretical' but a very real issue. Even though most concrete construction does seem to last pretty well.
If you keep the water out, there's no reason why 2x4 and sheetrock shouldn't last a good long time.
I live in New England, and there's plenty of old post-and-beam construction that's held up for a couple of hundred years. Some houses still have their original interior trim and softwood floors, and if that holds up, I can't think of any reason why 2x4s shouldn't.
But old New England construction lasts because it's maintained. New roofs, new clapboards every 50 years, regular painting, interior repairs and renovations. With land costs what they are in many regions, it's cheaper to take care of a good house rather than just letting it fall apart over 50 years.
Large dry laid stone can easily last thousands of years as long as the foundation is solid. Consider the pyramids both in Egypt and South America plus a host of other very old structures. However, you need to avoid tension, earthquakes, and unstable ground, can’t build very tall etc. High construction costs, slow build times, and serious limitations in what structures are viable shows just why we mostly abandoned the technology.
Mortar is basically indefinitely replaceable with constant maintenance and has lower upfront costs. So it’s generally a much better option.
Regular reminder that stainless steel reinforcement exists, is used bridges and it's use outside is growing, and it will last a thousand years.
Also there is Basalt, carbon fiber and even reinforcement out of used wind turbine blades, which is used in Britain for HS2, and other non-steel reinforcements, which can give you a structure nearly impervious to weathering.
On wood: In Europe we've been using Mass Timber for decides, and it's really good from Carbon perspective and outperforms RCC for small to medium residential and office buildings. Probably not going to replace RCC in infrastructure and industry, but what do I know
This has been a big issue with stainless steel climbing anchors and hangars, as it leads to sudden catastrophic failure with little warning, as you don’t get rust like normal steel. Some areas near the ocean have had failures in as little as 5 years - faster than if they’d used normal steel.
Even 316 rusts and corrodes, and that should be fairly obvious to most users if they actually look at the bolts before trusting them.
Not what you want in rebar (or climbing anchors!)
Certainly more involved and time consuming than, say, replacing some siding or moving a wall inside a stick built house but its all doable.
Pre/Post stressed components? Yeah good luck.
I would even say it is the opposite, you are lucky to have access to cheap enough wood.
No seriously, i do not see a single advantage of a wooden house. But I am eager to hear.
Cheaper (where I am). Let’s WiFi signals through easier, so I need fewer access points.
I’ve worked with both, and the main advantage of concrete would be the sound insulation. But I feel like a quality wood + drywall + insulation installation can come close enough for residential purposes.
They sequester carbon rather than produce it.
They're easy to modify and expand.
They're durable and last forever if you take care of them.
Plus the carbon sequestration
And in the case of craftsman style homes the use of wood is very beautiful but of course you could throw a few planks of wood onto a concrete shell.
It’s softer too, I lived in a condo that was all concrete and granite, anytime you bumped into a corner or fell down it just hurt more than wood.
For larger construction, pumped concrete is cheaper to build. It’s generally (but not always) more fireproof without special measures being taken.
You think that concrete is stronger because it looks solid and heavy. In many cases, concrete or other masonry buildings are actually clad buildings with wood or other framing. Also, generally speaking a small scale, poorly built concrete structure will be more solid than a poorly built wooden structure.
I live in an urban house in upstate NY, it’s a wood frame house built in 1925. It’s not a luxury or high-end construction, but there’s no structural reason that it won’t be standing in 2125. Keep a roof on it and control storm water and you’re good to go.
That’s an American thing.
The walls in my brick house in the UK literally are a foot thick of brick. Even internal walls.
The chemical reaction for the cement in concrete generates C02 in a 1:1 ratio with the amount of cement produced. Unless you're capturing it you release 1 ton of C02 for your 1 ton of cement. Steel for rebar is even worse, the ratio of C02 generated is greater than 1:1. None of this includes any of the energy you used to heat any of the ingredients either.
Even plastic is better, some of the Carbon & oxygen get sequestered in the plastic.
A process to completely sequester or not generate any C02 in the production of cement & concrete that was cheap & easy would be a Nobel prize winning innovation. If the whole world switched to that it would be more significant than switching all vehicles in the world to electric.
https://www.csmonitor.com/World/Global-News/2016/0430/Why-ar...
"A six-story building collapsed Friday night in Nairobi, killing at least a dozen people. Several buildings in Kenya have collapsed in the past year. Why?"
https://www.youtube.com/watch?v=okPYJ4l-lBI
Only the big ones end up in the media..
But you are right it seems like an overestimate. I found this showing 17 buildings collapsed in eight years, citing a CMU study:
https://www.thenewhumanitarian.org/news/2016/05/02/kenya-s-l...
In any case, the typical American wooden home is not going to have a family above you. :)
https://www.google.com/maps/@42.2662623,-71.8167462,3a,75y,1...
And lots of basements were packed eaeth, a whole nother level of 'unfinished'
Note that this foam is foil faced meaning it insulates against radiation energy as well as conduction or convection.
I doubt interior load supporting walls are 2x6. Often there are internal 2x6 walls, but that is to allow extra space for plumbing - 2x4 is plenty strong enough for load bearing in most houses, but toilet drains/vents don't really fit.
Could be another regional difference. Our code requires 2x6 minimum for load bearing walls.
Not a big deal for a qualified carpenter, but enough extra labor that you will pay extra for it in addition to materials.
I don’t understand if people posting this realise what a low bar this is? Brick and stone houses last a thousand years.
Many (brick and wood alike) were destroyed by fires and floods.
All in all, the lifespan of wooden structures is more than adequate, and significantly cheaper.
Further, they're designed to exist without modern heating and cooling, and many still don't have those (or they don't work very well). Yet they stand, and often still have perfectly-aligned original wooden trim work, despite being subject to swings in internal temperature and humidity that'd ruin a modern house in a hurry (modern ones are too air-tight to survive that, aren't built with any care to wood grain direction, and use much lower-quality timber throughout, including for trim, though they may benefit from extensive use of dimensionally-stable plywood).
edit: and even if some of the wood has rotten you can almost always just replace or sister up that piece and be absolutely fine.
https://imgur.com/user/AlphaStructural
What's interesting to me is you have Europeans marveling at houses built of flimsy wood instead of strong brick and concrete. Yet except for occasional water and termite damage what's failing in these houses is the concrete and brick foundations. Not the wood framing.
I wouldn't want a concrete house in the US without inspections so strict that the inspectors basically dictate when & how concrete may be poured, and/or laws explicitly breaking corporate liability protections for failure of concrete within some long time span, or otherwise ensuring that builders care very much that their structures last several decades without needing repair. I suspect they'd be crazy-expensive as a result.
In Florida a slab foundation and cinder block walls is what you want in a place with Hurricanes and a high water table.
On the California coast you want a stick built house. Because of earthquakes.
North east the frost line goes down several feet.
Lot of places you have expansive soils which will totally wreck a masonry building.
Also the problem the local workforce will be familiar with local designs. And likely to make mistakes if forced to build something different.
Why they are so old? Did owners not have money to rebuild?
Some people like the old style of architecture, which is possible but very expensive to reproduce with modern techniques (custom masonry, built in carpentry, that kind of thing)
And let me tell you, those old frames are unbelievable if they've been taken care of. If you do a renovation and open it up the wood is thick with tight, straight grain. A lot of these homes were built with old growth timber that was abundant at that time and unavailable today. The natural aging of the wood has dried out moisture and resins and makes for stronger lumber, albeit lumber that is more brittle which isn't a concern for how it is being used.
There's a good chance the wood was quarter sawn as well and if you have the original floorboards there's a good chance they were quarter sawn back then too. This, again, makes for better construction as the wood won't warp as much.
Why tear down something that is of historic value, and has a character and beauty completely missing from modern housing?
And Americans build a lot of detached single-storey houses [1], which mitigates some of the disadvantage of wood: Noisy neighbours? You've got a six-foot-plus air gap between your houses. Fire risk? Escape is trivial when every room has a ground floor window. Rain getting onto the wooden walls? Much reduced by a porch stretching around the entire building. Needs regular repainting? Easy when it's a single-storey building.
Wood is also substantially cheaper in the US than in the UK - so while it might not look like a cheap material from the prices at British wood stockists, Americans who call it a cheap way of building aren't paying those prices!
> Rain getting onto the wooden walls? Needs regular repainting?
Most “wooden” US homes do not have wood siding. Vinyl is extremely common, and most homes that predate vinyl have had vinyl installed because it eliminates the maintenance associated with painted wood. Mine is decorative masonry. (And I wish I had vinyl)
I thought all new homes in the past decade or so came with cement fiber siding like Hardibacker, Durock, or Wonderboard. I have not seen new construction with vinyl siding in a long time (west of Rockies).
Those are typically are used with masonry siding. Vinyl siding is usually put on OBS boards with a vapor barrier in between.
It’s OSB, then a weather resistant barrier, then the cement fiber siding on the outside nailed into the OSB.
Personally I don’t like vinyl siding because it looks cheap and it melts (this seriously happened to a friend of mine - the sun reflected off the windows of his neighbors house and melted his siding.)
They suck if you want to retrofit them to have modern heating and cooling. The high ceilings, giant windows on all sides, large open attics (vital for temp control without AC!), and generally poor sealing (=great if you need them to survive temp and humidity changes throughout the year, and not turn into a giant mold farm like a modern house would) all work against you.
Where I live now, ceiling heights are going back up. 10 years ago it was common to have 9 foot ceilings on the first floor, 8 foot on the second. Now it's common to have 9 foot on the second floor as well. And there are a not-insignificant number of houses being built with 10 foot ceilings.
I would rather spend less on my utility bills, and conserve the energy.
There are a few people fighting this, https://gracedesign.ie/ makes stunning beautiful house frames, and I'm having my own house built in wood right now. By coincidence, so are the people in the field next to me. But there's decades of prejudice to overcome.
It's not when you consider that we cut down most of our trees.
https://www.forestresearch.gov.uk/tools-and-resources/statis...
Construction evolves due to avaliable resources and local conditions. Transplanting a technique from one country to on other won't necessarily work.
If you have earthquakes such as in NZ, USA or Japan building concrete houses does not make a lot of sense.
[1] https://www.statista.com/statistics/612959/number-of-househo...
[2] https://www.statista.com/statistics/377896/owner-occupied-ho...