[HN Gopher] Concrete: The material that's 'too vast to imagine'
___________________________________________________________________
Concrete: The material that's 'too vast to imagine'
Author : DrNuke
Score : 136 points
Date : 2021-06-29 11:16 UTC (11 hours ago)
(HTM) web link (www.bbc.com)
(TXT) w3m dump (www.bbc.com)
| bvoq wrote:
| Mini question: Isn't there a lot of sand on the bottom of the
| oceans and we're just running out of easily accessible sand?
| ddulaney wrote:
| There is! Lots of places already rely on marine sand, but
| extracting it has its own challenges and environmental issues.
|
| Lots of details here:
| https://worldoceanreview.com/en/wor-3/mineral-resources/depo...
| bluGill wrote:
| Needs to be the right kind of sand. When your kids are playing
| at the beach you don't really notice that some sands are better
| for sand castles than others - and few could care if it was
| pointed out to them. When you want to make a building last
| though the properties of the sand matter.
| lmilcin wrote:
| Fun, useless fact: a single structure, Three Gorges Dam, has more
| concrete in it than half of all living people.
| jandrese wrote:
| I'm pretty sure I have around 0% concrete in my body.
| grae_QED wrote:
| I'm pretty sure everyone has 0% concrete in their body.
| bluGill wrote:
| You seem to have forgotten than you used to eat rocks just
| like every other baby. Some of those babies are eating
| concrete rocks. So some people have > 0% concrete in their
| body.
|
| Not significant, but still.
| aurizon wrote:
| Concrete is a mixture of different sizes of a strong stone, like
| granite or silicate in a carefully graded mix of sizes from sand
| sizes upwards. The idea is to get the final block to be 100%
| stone(impossible) or as close as practical. You then cement this
| all together (mixing all the while) with powdered cement. Cement
| is a mixture of C3S: Alite (3CaO*SiO2); C2S: Belite (2CaO*SiO2);
| C3A: Tricalcium aluminate (3CaO*Al2O3) (historically, and still
| occasionally, called celite); C4AF: Brownmillerite
| (4CaO*Al2O3*Fe2O3). This is melted at high temperatures into
| 'clinker' (when melted it resembles lava from which classic roman
| cement was made as it collected as a fine volcanic ash). Rock has
| water of hydration strongly bound into, when melted into clinker
| the water evaporates = clinker. The clinker is ground to a powder
| and added to the graded mixture of sand and small rocks and water
| is added - it is then mixed very throughly and the final water
| ratio is established. It is then poured into the moulds that hold
| the cement in the final shape you want when it sets. You vibrate
| and shake well to get the air bubbles out and then you want for
| it to cure. As it cures the powdered clinker absorbs water and
| turns into the fully hydrated final (set) form. It can take
| months to fully set, but usually after a day it is into the
| 60-75% area of final strength. This makes heat = big things need
| active cooling, small stuff not so much. As it cures and very
| strong matrix of hydrated crystals fills all the space = set or
| cured concrete. Reinforcing can be any strong material that is
| not brittle. Usually steel rebar is OK for a dry life structure.
| For damper areas you can use epoxy coated rebar, then galvanized
| rebar, then epoxy coated and galvanized rebar. For the next stage
| stainless steel rebar is the high cost option. Nuclear power
| stations use SS rebar in some cases.
|
| Corrosion. Steel corrodes. Steel = FE,(1 atom) corroded steel =
| FeO (2 atoms = bigger) if oxygen reaches the steel it will make
| FeO - these 2 atoms are bigger than the one atom of Fe. This
| means the FeO will expand with an irrestible force (200 times as
| strong as concrete). It is this rebar expansion that makes huge
| cracks = more water in, = bigger cracks etc. FeO is as weak as
| kleenex as a support member. so as the concret and rebar turn
| into powder the strngth of the structure vanishes. At some point
| you get this sort of collapse - all of which was preventable by
| proper design and maintenance. Punishment? imprison them in the
| basement of one of their badly made buildings and let them spend
| their life waiting for the inevitable collapse. Concrete Wiki
| https://en.wikipedia.org/wiki/Cement
| raptor99 wrote:
| This just in! There is more rock on/in Earth with greater mass
| than trees and animals on Earth!
| woleium wrote:
| > If future archaeologists do the same for us, what material
| might they choose to define the 21st Century? Silicon? Plastic?
| Both are candidates, shaping the world for better and for worse.
| But if the decision were based on scale alone, then there can be
| only one answer: we are living in the age of concrete.
|
| lol, yes! the "plasticine". ;)
| bjt2n3904 wrote:
| I seem to remember reading this article from here: "The Most
| Effective Weapon on the Modern Battlefield is Concrete"
|
| https://mwi.usma.edu/effective-weapon-modern-battlefield-con...
| azalemeth wrote:
| That was very interesting -- thank you. I do wonder what the
| locals thought about it all though. In my country planning laws
| are a big big deal!
| [deleted]
| FredPret wrote:
| Military strategy is ultimately about delivering your bullets
| to the enemy and putting a hard barrier between their bullets
| and your troops.
| sbierwagen wrote:
| Most effective in CI warfare, maybe. Static defenses have
| historically not done well against tank armies.
| ars wrote:
| "And if its rate of growth continues, it will overtake the total
| weight of Earth's biomass sometime around 2040."
|
| Rather than impress me with the amount of concrete, this actually
| impresses me with just how incredibly huge the biosphere is!
| That's an _enormous_ amount of life.
| danpalmer wrote:
| Concrete is one of the biggest sources of emissions in the world
| and it feels like a blind spot in our push for greener solutions.
|
| Is there any research being done into alternatives that will
| scale to what we use concrete for? I've seen alternative home
| building methods, and different urban planning can reduce the
| need for large buildings that need it, but I haven't seen good
| alternatives for roads, tunnels, bridges, etc. Steel sometimes
| works but has its own problems and is more expensive.
| 0x_rs wrote:
| Concrete production represents 4-8% of all worldwide CO2
| production. It's a significant percentage. There's talk on
| sequestering CO2 in concrete itself but I'm not sure how far it
| has gotten. I do remember some plants in France or Germany
| having facilities to process clinker byproducts. I wonder how
| more efficient is that.
| wil421 wrote:
| Why don't we focus on the problems we can solve today? Cars,
| power generation, and improve industrial process that emit
| green house gasses.
|
| We could solve these issues "today" in a sense. Creating new
| carbon neutral building materials that last as long as current
| stuff seems like a huge risk.
|
| https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emis...
| ajmurmann wrote:
| Why not both? If we had a carbon tax the market would drive
| us to save wherever is most achievable
| yonaguska wrote:
| That is until the well-connected lobby carbon tax loopholes
| into the implementation and use the carbon tax yet another
| tool for regulatory capture to stomp out competition. Or,
| companies simply shift more production to developing
| countries to skirt taxes. We can create ecological
| disasters over there instead...
|
| While I like the idea of attaching monetary costs to
| otherwise ignored externalities, I don't see the carbon tax
| having any chance of being fairly and effectively
| implemented.
| kaibee wrote:
| > That is until the well-connected lobby carbon tax
| loopholes into the implementation
|
| This is a fully general counter-argument against doing
| anything.
|
| iirc Canada has a carbon-tax and its working fine?
| orhmeh09 wrote:
| Working fine by what measure?
| csw-001 wrote:
| It's funny you should say this - I just recently was on an
| airplane with a bunch of folks returning from a big Vegas
| concrete convention. Eavesdropping a bit here and there, it
| seemed the topic of "greener" concrete was big. The person in
| the seat next to me was describing how they recently started
| using a concrete and steel fiber mix so they could pour less
| and achieve the same strength and durability - the main
| "customer pitch" she told me was that it would was a lot
| greener. No idea if any of that is true, but it was interesting
| to see how focused on it they all were.
| ceejayoz wrote:
| I'd imagine it's kinda like "clean coal" - more marketing
| buzzword than actual significant benefit.
| TheFreim wrote:
| > significant benefit
|
| Isn't at least a little benefit alright? It's not
| "significant benefit" or "nothing.
| ceejayoz wrote:
| Not necessarily. At times, a tiny band-aid on things can
| be counterproductive. See replacing plastic straws with
| paper/reusable ones; it's a drop in the bucket, and it's
| used in part to distract from the much larger overall
| issue of single-use plastics.
|
| https://en.wikipedia.org/wiki/Greenwashing
| TheFreim wrote:
| I don't see how paper straws distract from anything.
| Every time I see a paper straw my immediate thoughts are
| about how it's not plastic that'll be getting thrown out.
| ceejayoz wrote:
| https://blogs.scientificamerican.com/observations/more-
| recyc...
|
| > At face value, these efforts seem benevolent, but they
| obscure the real problem, which is the role that
| corporate polluters play in the plastic problem. This
| clever misdirection has led journalist and author Heather
| Rogers to describe Keep America Beautiful as the first
| corporate greenwashing front, as it has helped shift the
| public focus to consumer recycling behavior and actively
| thwarted legislation that would increase extended
| producer responsibility for waste management.
|
| > For example, back in 1953, Vermont passed a piece of
| legislation called the Beverage Container Law, which
| outlawed the sale of beverages in non-refillable
| containers. Single-use packaging was just being
| developed, and manufacturers were excited about the much
| higher profit margins associated with selling containers
| along with their products, rather than having to be in
| charge of recycling or cleaning and reusing them. Keep
| America Beautiful was founded that year and began working
| to thwart such legislation. Vermont lawmakers allowed the
| measure to lapse after four years, and the single-use
| container industry expanded, unfettered, for almost 20
| years.
| shkkmo wrote:
| I don't see any evidence that the push against plastic
| straws is used to distract from other single use
| plastics.
|
| Indeed, I see the opposite. I see advocacy groups that
| are fighting against single use plastics using anti
| plastic straws campaigns as a way to spark conversations
| about other kinds of single use plastics.
| NoOneNew wrote:
| No, there are some companies actually trying to create
| "greener" cements and concrete formulations. We can
| absolutely split hairs about it, but some are significantly
| better than conventional and are in the pipeline for use.
| However, still years away due to regulation testing and
| standards adoption.
| [deleted]
| [deleted]
| baybal2 wrote:
| > Is there any research being done into alternatives that will
| scale to what we use concrete for?
|
| Flyash, and other pozzolanic industrial wastes. There are
| literally mountains of it.
|
| Problem? There is no "standard flyash," every power station
| uses a bit different fuel. Same for industrial wastes.
|
| Second option are natural geopolymers, but they are not that
| common, and coincidentally, most of countries with a lot of
| geopolymer deposits are rather rich, and that undercuts
| economic incentives.
| kieranmaine wrote:
| This company creates reduced carbon cement -
| https://www.ecocem.ie/ecocem-materials-limited-raises-e22-5m...
|
| This podcast has a couple of interesting mentions on low carbon
| concrete - https://www.npr.org/transcripts/923966126
| nelblu wrote:
| https://www.carboncure.com/
| LeifCarrotson wrote:
| Honestly, I think we actually want a high-carbon cement: One
| full of graphene or other carbon compounds, pulled from the
| atmosphere. Per the article yesterday [1] we need to remove 2
| teratonnes of CO2 from the atmosphere to meet IPCC targets.
| Maybe some of that will be done by taxpayer-funded carbon
| sequestration operations that exist only to pump the carbon
| 'away' in underground reserviors. But I think that if we've
| laid down 1 Tt of concrete, and could develop something
| better than that which is carbon-negative, people would be
| more than happy to pay for that CO2 sequestration, and that
| progress might actually survive an election cycle.
|
| [1] https://spectrum.ieee.org/energy/renewables/engineers-
| you-ca...
| [deleted]
| vegetablepotpie wrote:
| Yes there is. Geopolymer cement provides an 80% reduction in
| co2 emissions vs traditional cement. CarbonCure has developed a
| version of concrete that _absorbs_ co2 during its production,
| though it cannot be poured and can only be used to make prefab
| shapes [1].
|
| An issue with these new cements is that there is no economic
| incentive for companies to change production processes and
| switch.
|
| [1] https://youtube.com/watch?v=MkE-2npiqFc
| tastyfreeze wrote:
| It isnt just cost that prevents a switch. Some building codes
| explicitly state Portland cement as the allowed material.
| Geopolymer proponents have been working to change building
| code to stating required material properties instead.
| Unsurprisingly, geopolymers have taken off in countries with
| less regulation.
| patrickk wrote:
| One material that should be used much more in building but
| isn't: straw!
|
| It's become a recent obsession of mine.
|
| * has a long history of use (no research needed)
|
| * is eco friendly (in fact sequesters carbon)
|
| * cheap
|
| * readily available
|
| * pliable material that is forgiving to build with, even for
| novices
|
| * quick to erect walls
|
| * is a waste material - usually ploughed back into fields or
| burned
|
| * has very impressive thermal and sound insulation, so no
| additional insulation is needed, unlike a concrete walled home
| or building
|
| I could go on....
|
| Of course not every building or structure can be made from
| straw bales, but many houses, warehouses or smaller commercial
| buildings could be. It's a very low hanging fruit in the battle
| against climate change.
|
| https://www.amazon.com/Building-Straw-Bales-Self-Builders-Su...
| vxNsr wrote:
| I read that straw is basically outlawed bec it's hard to make
| a house with it and still be on the right side of fire safety
| codes. Especially if you're using it as part of your
| insulation strategy.
| mercutio2 wrote:
| A straw bale wall burns MUCH more slowly than a stick frame
| wall.
|
| So this is really not accurate (and standard fire codes
| have accepted this).
|
| The bigger problem is that people don't like giving up so
| much of their footprint to 18-inch-thick walls.
| patrickk wrote:
| Where is it outlawed?
| legym wrote:
| Been looking into graphene and it can reduce the amount of
| concrete and increase the strength. Of course, can graphene be
| made at a commercial level and out of the lab
|
| https://www.graphene-info.com/graphene-based-concrete-used-c...
| [deleted]
| XorNot wrote:
| Concrete though is big and stationary. It needs heat, not
| combustion to make, so it is amenable to fuel source switching.
|
| For me it's in the bucket of "problems which don't matter till
| we solve electricity". Clean, cheap electricity == clean, cheap
| concrete.
| phreeza wrote:
| The majority of the CO2 emissions from concrete come from the
| production chemical reaction, not from the heat generation,
| though.
| XorNot wrote:
| Wikipedia [1] suggests 50% is from calcination and 40% from
| burning fuel. There's plenty of room for reductions on the
| fuel side.
|
| [1]https://en.wikipedia.org/wiki/Environmental_impact_of_co
| ncre...
| tromp wrote:
| > For a German artwork, Time Pyramid, a concrete block will be
| placed every decade for 1,000 years.
|
| It will take 1200 years as the pyramid will have 120 blocks in
| layers of 8x8, 6x6, 4x4, and 2x2 [1].
|
| [1] https://en.wikipedia.org/wiki/Time_Pyramid
| fredley wrote:
| A lot of the problems with concrete are actually problems with
| steel reinforcement. Concrete alone is incredibly long-lived and
| durable, see the Pantheon in Rome. However steel rusts, expands
| and weakens within decades, even when you do everything right.
| tastyfreeze wrote:
| By using basalt or other composite rebars the concrete cancer
| problem is solved.
| RosanaAnaDana wrote:
| What are basalt rebar? Never heard of these.
| tastyfreeze wrote:
| https://basalt-rebar.com/
|
| https://www.youtube.com/watch?v=mRWdHpopETI
|
| Basalt is a pretty amazing material. This is just one use.
| Basalt is also used to make insulation, low skid tiles, and
| corrosion resistant pipe liners.
| RosanaAnaDana wrote:
| Thanks for the links! I love building material science.
| masklinn wrote:
| It's what it sounds like: rebar made from basalt (basalt
| fibers specifically): melt the basalt, extrude it, mix it
| with polymers, shape into a REinforcing Bar.
|
| Problem's it's way more expensive than steel. It's also a
| pretty young material so I don't know how much safety and
| longevity information we have. Steel's well understood.
| tastyfreeze wrote:
| The expense is an upfront cost. Using basalt rebar we
| could be building 100 or 150 year bridges instead of 50
| year bridges. We know basalt concrete structures wont
| fail from the reinforcement rusting away. We just haven't
| been using basalt rebar long enough to know the long term
| failure modes.
| masklinn wrote:
| > The expense is an upfront cost. Using basalt rebar we
| could be building 100 or 150 year bridges instead of 50
| year bridges.
|
| But is that something we're trying to build? As the
| saying goes, it takes an engineer to design a building
| that's barely standing.
|
| We know how to build stuff which lasts for centuries,
| there's plenty of those lying around in the old world.
| bilbo0s wrote:
| Basalt rebar does not have the tensile strength of steel
| rebar. During extreme stress, steel rebar allots time for
| escape, increasing the survivability of an event. The
| behavior of basalt is significantly different.
|
| Just different materials, with different performance
| profiles, that you can use to beneficial effect in
| different environments. But you have to know and
| understand the implications of the different performance
| profiles.
|
| I'm not going to do a whole engineering lecture here, but
| there is a really good concrete nerd who can outline
| this, and so much more, for you on his youtube channel if
| you're interested. He's a good engineer and I've been
| impressed with the accuracy of the material he presents
| as well as the accessibility with which it is presented.
|
| Tyler's channel:
| https://www.youtube.com/channel/UCrvfiHNDS_QI-FgKQSmTITQ
|
| More detailed explanation of tensile strength
| implications in structures:
| https://www.youtube.com/watch?v=thUZImUTZn0
| tastyfreeze wrote:
| Nice! Thank you for a few hours of entertainment.
| bilbo0s wrote:
| LOL!
|
| No problem.
|
| Tyler's definitely a nerd, but he's one of those
| magnificently brilliant nerds that you can't help
| watching for hours at a time.
| [deleted]
| mmmBacon wrote:
| Here's a good explanation on the differences modern concrete
| and Roman concrete. It turns out they are pretty different
| materials.
|
| https://www.sciencealert.com/why-2-000-year-old-roman-concre...
| baybal2 wrote:
| > Concrete alone is incredibly long-lived and durable
|
| It can be, but usually isn't. People don't make concrete
| buildings to last 100 years.
|
| Normally, chlorides, and carbonation set the expiration date on
| a building.
|
| In China, 20 year old, if not 10 year old highrises are knocked
| down. Before I saw that myself, I thought that it's madness.
| hguant wrote:
| Part of that is because they have to other wise the building
| would collapse on its own.
|
| A big issue people don't talk about is that a lot of the
| concrete China makes is subpar and not up to spec by US or EU
| standards - they don't use the right (aka more expensive)
| grade of sand, so the concrete doesn't bind as strongly as it
| should. The sand used to make concrete has to have rough
| edges, something about the surface area, which ironically
| means that desert sands aren't very useful - they've been
| rounded by wind erosion and rubbing against other sand
| grains.
| jhgb wrote:
| What I was wondering some time ago...couldn't you sieve
| desert sand for larger grains and then crush them?
| pueblito wrote:
| It's not surface area so much as the faceted sides of
| crushed sand lock together when compressed instead of
| sliding past each other
| RosanaAnaDana wrote:
| Building with concrete to knock down in 10-20 years is actual
| madness.
| magicsmoke wrote:
| There's a kind of twisted logic to it. If your construction
| techniques are constantly improving and the high volume of
| construction incentivizes you to develop more cost
| efficient construction technologies, then planned
| obsolescence of buildings is like planned obsolescence of
| phones. Build soviet block apartments, knock down in 20
| years, replace with prefab building compartments with
| wiring and plumbing built in at the factory. Then export
| the prefab technology worldwide to take advantage of the
| infrastructure boom in other developing countries. Isn't
| build fast, break fast, and learn fast the whole silicon
| valley ethos?
| silicon2401 wrote:
| Why don't we just use concrete by itself? Is steel necessary
| for using concrete the way we do in modern times?
| codeOnMaster wrote:
| Yes, steel is required. In the design of concrete structure,
| concrete is assumed to have zero (0) tensile strength.
| PeterisP wrote:
| In order to use concrete by itself, you have to limit
| yourself to specific architectural structures which are very
| much unlike modern buildings - essentially, you can build
| quite high ancient-looking structures with everything held up
| on arches (which take up space and material), but you can't
| build a simple box-shaped building from concrete without
| steel rebar.
| mc32 wrote:
| It is now possible to use wooden structural components to
| build modern skyscrapers. Maybe not 100 storeys buildings
| but 30 storeys is feasible[1].
|
| [1] https://www.bbc.com/future/article/20171026-the-rise-
| of-skys...
| jcims wrote:
| Great video on prestressed concrete members -
| https://www.youtube.com/watch?v=P13Mau2VUWw
|
| (Really good channel overall on civil engineering)
| yodelshady wrote:
| For the way we use it, yes. Concrete works well in
| compression but is _horribly_ weak in tension; a supervisor
| of mine compared it unfavourably to a ginger nut biscuit.
| Probably hyperbolic but you get the idea.
|
| Big, arch-y structures like the Roman pantheon work, because
| everything is in compression. But that's a lot of not-
| economically-useful space.
| marcosdumay wrote:
| Explaining the asnwers in another way, yes, steel is
| necessary for both large horizontal openings without pillars
| and large vertical heights.
| namirez wrote:
| Basically concrete is good only for compressive loads. Under
| tension it easily cracks. The steel reinforcement adds
| tensile strength to concrete.
| codeOnMaster wrote:
| In fact, the concrete MUST crack in the tension zone in
| order for the steel to take effect and provide tensile
| capacity to the member.
| kube-system wrote:
| Only if you don't prestress the reinforcement.
|
| https://en.m.wikipedia.org/wiki/Prestressed_concrete
| acchow wrote:
| How often are skyscrapers built using prestressed
| concrete?
| mrfusion wrote:
| Why can't we use carbon fiber or aluminum or anything that
| won't rust?
| lurquer wrote:
| > Why can't we use...
|
| You can. Nobody's stopping you.
|
| Perhaps you meant "they" instead of "we".
|
| Pet peeve.
|
| I've found when you use the proper pronoun -- 'they' in
| this case, unless you make concrete -- it focuses your
| thinking.
|
| That is, if you want to know why 'they' do something,
| you'll naturally ask 'them'. But, when you use 'we', you're
| more likely to just imagine your own solution.
|
| Nothing personal.
|
| 'We' is the bane of my existence...
|
| In order for this post to be somewhat relevant, I'll add
| this... I see corroding rebar as a feature and not a bug;
| it assists in the natural degradation of concrete and it
| gives me some comfort to know that the distant future will
| have no signs of the concrete monstrosities that litter out
| landscape. Thanks, rebar.
| rsync wrote:
| "Why can't we use carbon fiber or aluminum or anything that
| won't rust?"
|
| You can. Stainless steel rebar is a thing and would,
| largely, solve the problem of spalling due to rusting steel
| reinforcements.
|
| As you can imagine, stainless steel rebar adds a
| significant cost.
| ggcdn wrote:
| One of the big reasons is ductility. We want structures to
| show signs of distress before failing catastrophically.
| With ductile reinforcing (steel), the deformation at which
| failure occurs is easily 5 times larger than the
| deformation where yielding occurs. Large cracks will open
| up, it hopefully gets noticed, and there is a chance to
| intervene.
|
| With GF or CF reinforcing, failure is sudden and
| catastrophic.
| UI_at_80x24 wrote:
| To avoid the problems of rust, epoxy coated steel is often
| used. It costs more, so in situations where the contract is
| won by the lowest bidder (unless it is expressly required),
| you don't get it.
|
| So as a result, buildings that could last 200 years start
| to crumble after 50.
| baybal2 wrote:
| Epoxy coated rebar was a trap, and is now being banned
| around the world. Paradoxically, the epoxy coat can make
| corrosion worse than the bare steel, let alone
| galvanised.
| ggcdn wrote:
| Not sure why you're being downvoted, because you're
| right, atleast on the west coast of north america. My
| firm hasn't use epoxied rebar since like 1990, and we
| removed all references to it on our drawings long ago.
|
| The coatings were super fragile, and often damaged while
| being placed in the field. Then someone had to come along
| with magic paint and touch up all the cracks. But of
| coarse they would never find 100% of them...
| throwaway0a5e wrote:
| He's getting downvoted because more modern versions of
| epoxy coated rebar are still widely used in new
| construction. It wasn't the silver bullet for salted
| roadways it was sold as but it has its place.
| ggcdn wrote:
| which regions and industry do you see them used? In west
| coast buildings, its uncommon.
| dTal wrote:
| Cost would be my guess.
| baybal2 wrote:
| > Why can't we use carbon fiber or aluminum or anything
| that won't rust?
|
| We can, we do, just steel is super duper cheap, and
| workable.
|
| Ironically, it's China now who leads the world in GFRC
| (glass fibre reinforced concrete) construction to get those
| miniscule cost savings on steel (despite it being world's
| biggest steel producer.)
|
| There is also basalt fibre reinforced concrete that is
| supposed to be superior to glass fibre, and can come in
| workable varieties (heat it up with a torch, and bend.)
| toss1 wrote:
| We actually can - fiberglass rebar has many advantages over
| steel, among the first being that it does not corrode and
| expand. It's also much lighter and easier to transport to
| and on the worksite.
|
| It is starting to see widespread use in the construction
| industry, but far too slowly. A quick search on "fiberglass
| rebar" will return many manufacturers and articles.
| angst_ridden wrote:
| However, in earthquake country, we don't build with
| unreinforced concrete for the obvious reasons.
| masklinn wrote:
| > Concrete alone is incredibly long-lived and durable, see the
| Pantheon in Rome.
|
| That requires massively overbuilding the concrete structure,
| and many of the things we mold concrete into simply would not
| be feasible in unreinforced concrete, it's only strong in
| compression.
|
| Plus the Pantheon and friends are good examples of survivor
| bias, for the on Pantheon there are hundreds of insulae which
| didn't survive.
| jbay808 wrote:
| This is a total misunderstanding of survivorship bias. It
| would be like encountering a 1,000 year old man and
| attributing his age to merely survivor bias rather than
| investigating whether it has something to do with the magical
| beans he ate.
| ginko wrote:
| They didn't even try to imagine it though.
|
| According to the linked article[1] there's about 1.1 Tt of
| concrete on the planet. At a density of 2.4t/m3 that's 458
| billion m3 or 458km3. That'd be a cube of with a side length of
| 7.71km or about the height of Mount Jannu[2] from ocean level.
|
| [1] https://www.nature.com/articles/s41586-020-3010-5 [2]
| https://en.wikipedia.org/wiki/Kumbhakarna_Mountain
| baybal2 wrote:
| And with most of it being poured in the last 20 years in Asia.
|
| 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.
| rootusrootus wrote:
| That's ironic, since wood construction has a much longer
| history than reinforced concrete, and I'm not by any means
| convinced that the latter will be as durable.
| Retric wrote:
| Reinforced concrete structures are known to have a
| relatively short lifespan. Wood easily lasts several times
| as long with proper care.
| kiliantics wrote:
| Depends on how the wood is used. Timber frame structures
| can last centuries or even millennia. Stick-built is not
| as durable.
| ekidd wrote:
| I would imagine that a lot comes down to maintenance,
| especially roof and siding maintenance.
|
| 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.
| neals wrote:
| Is there no proper care for concrete though?
| aspaceman wrote:
| Rebar reinforced concrete rusts.
|
| 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?
| aksss wrote:
| Small nit not to take away from your larger point - I'm
| not sure the colosseum is a good example of a concrete
| structure for comparison to the concrete buildings of
| current age being discussed. The colosseum did use
| concrete for the arches, but was primarily built of
| limestone block secured with metal clamping. Then plenty
| of brickwork was used. Concrete was integral to the
| colosseum, but (I believe) a relative minority of the
| material on the whole.
| Retric wrote:
| Skyscrapers use a great deal of steel, but their still
| reinforced concrete structures.
| Haemm0r wrote:
| Carrying strucuture is mainly reinforced steel(classic
| pillar + concrete floor/ceilings design), walls are
| usually bricks.
| baybal2 wrote:
| > There are options for non-rusting rebar, and non-
| rusting coatings, but I believe they're expensive.
|
| 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.
| [deleted]
| abecode wrote:
| In Marina Del Rey, the rebar in the concrete sides of the
| marina are fed a trickle of electricity to prevent
| corrosion. I'm not sure how common this is though outside
| of marine environments.
| Scoundreller wrote:
| Maybe not electricity, but sacrificial anodes are
| otherwise a thing on bridges, boats, water heaters...
| [deleted]
| bdamm wrote:
| It's called cathodic protection and it is common.
| Retric wrote:
| Keeping it dry and sealing large cracks helps, but
| reinforced concrete breaks down on contact with air so
| not really. Best option would actually be keeping it in a
| vacuum, but that's just not cost effective.
| bilbo0s wrote:
| If concrete is reinforced, even with proper care, physics
| will get you eventually. It'll happen faster if you're
| near a coast. It'll take longer if you're inland. But
| eventually, the inevitable will happen. Our reinforced
| concrete structures will never last as long as, say, the
| Pyramids.
|
| 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.
| lolsal wrote:
| > Our reinforced concrete structures will never last as
| long as, say, the Pyramids. > Wood will last longer,
| again, with proper care.
|
| 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!
| wongarsu wrote:
| Concrete is strong in compression, but weak in tension or
| shear forces. To solve that you reinforce it with rebar
| (basically steel bars). But concrete is porous to water,
| and steel rusts. When it rusts it expands, which damages
| the concrete. The only ways to escape that is with
| coating the rebar (hard to do well) or reinforcing with
| something else (not many options we know of). You can try
| to prevent or patch cracks in the concrete to slow down
| the process, and you can use more rust resistant steel.
| Both of them prolong the lifetime a lot, but they only
| delay the inevitable.
|
| 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).
| bilbo0s wrote:
| Sorry. Perhaps my wording was poor.
|
| 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.
| chongli wrote:
| As iconic as the pyramids are, they're not very useful. A
| better comparison may be the Pantheon in Rome. Nearly two
| thousand years old and in continuous use throughout its
| life. There are a number of other Roman structures that
| have seen continuous, heavy use for over a thousand
| years.
|
| There are actually quite a number of ancient temples,
| churches, bridges, castles, and roads still in use
| throughout Europe, Asia, and the Middle East. Horyu-ji
| [1] in Japan is a 1300-year-old wooden Buddhist temple
| that's still in use today!
|
| [1] https://en.wikipedia.org/wiki/Horyu-ji
| maayank wrote:
| What timespans are we talking about here? 30 years until
| reinforced concrete starts failing? 100?
| stonemetal12 wrote:
| About 100 years is the max life span of reinforced
| concrete. If not done to a high standard half that.
| pmontra wrote:
| That bridge in Italy collapsed after 51 years.
|
| https://en.wikipedia.org/wiki/Ponte_Morandi
| afiori wrote:
| 51 years and criminal care.
|
| But if we are comparing concrete and wood as construction
| material we should use buildings that can be built with
| either.
| ska wrote:
| As usual "it depends".
|
| 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)
| ak217 wrote:
| Reinforced concrete is easier to maintain indefinitely
| than wood, because it's easier to seal against moisture,
| especially in harsh environments. Just because there are
| plenty of poorly built/maintained reinforced concrete
| structures, doesn't mean that it can't be built for
| longevity.
| ohazi wrote:
| Maintenance of steel reinforced concrete is an all-or-
| nothing affair. You either get it right and seal
| everything perfectly and monitor everything perfectly and
| repair tiny cracks before they allow moisture to get in,
| or you're sunk. If surveillance is lax for a few years
| you can easily end up with damage that can't be repaired.
|
| 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.
| fsloth wrote:
| "...or you're sunk"
|
| 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.
| afiori wrote:
| Both of those building would have been almost impossible
| to build with wood
| ak217 wrote:
| It's relatively straightforward to overengineer concrete
| to the point where it will take many decades, not just
| years, of neglect for damage to become unrepairable.
|
| 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.
| ohazi wrote:
| > A lot of this discussion is comparing apples to
| oranges.
|
| 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.
| majormajor wrote:
| Why is reinforced concrete easier to seal? Why couldn't
| you apply the same sealant to wood? And why wouldn't you
| have the same issues, such as when you punch a hole in
| the exterior to mount something, or run wires, etc, you
| now have to make sure that sealant stays in good shape?
| Or expansion joints?
| jazzyjackson wrote:
| I wonder if wood construction is more forgiving than
| concrete once you get to a point where it was neglected
| for some time. Wood will rot and need replacing, but if
| your concrete is ignored and the rebar starts crumbling,
| you can't just slap fresh concrete over it and call it a
| day, right?
| mcguire wrote:
| Steel rebar doesn't crumble. Rusting steel expands,
| causing more cracks, which then allow more water
| intrusion and more rust.
| Retric wrote:
| Rust isn't load baring, it's effectively replacing steel
| with a powder which is a huge issue if you needed the
| steel in the first place. Cracks from expansion make both
| this worse and make it obvious, but even without that it
| would still be a critical failure.
| iratewizard wrote:
| I'm no expert, but repointing concrete is essentially
| doing just that
| Retric wrote:
| Not for reinforced concrete, the rusted rebar is still
| rusted after repointing. Which causes ever increasing
| internal stress and lower strength over time.
|
| The only way to fix it is to remove existing rebar and
| replace it which isn't viable on most structures.
| galangalalgol wrote:
| What about stone/brick dry laid or with mortar? A lot of
| roman stuff is around, but there was so much to start
| with it could easily be selection bias.
| ClumsyPilot wrote:
| Most houses last basically forever with "proper care",
| the question is how difficult/likely is 'proper care'
|
| 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
| lazide wrote:
| Stainless reinforcement is definitely not guaranteed to
| last 1000 years. Most grades of stainless are susceptible
| to stress corrosion cracking in any environment
| containing chlorides (even at relatively low levels),
| which is pretty much any bridge, industrial, or habitated
| structure - everything from road salt, to bleach, to
| chlorinated tap water can be a problem over a long enough
| period of time.
|
| 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.
| throw1234651234 wrote:
| Reinforced concrete buildings have better thermal and sound
| isolation. They are obviously more resistant to damage.
| Proof of this are Khruschev-era Soviet apartment blocks
| that are standing today.
|
| 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.
| greesil wrote:
| The last building I lived in was reinforced concrete. It
| was great, I definitely couldn't hear the neighbors,
| except I could still hear the people upstairs walking
| around in what sounded like tap shoes at 2am on Saturday
| nights. Some people just have more fun than me.
| baybal2 wrote:
| > Khruschev-era Soviet apartment
|
| 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.
| timeon wrote:
| > Reinforced concrete buildings have better thermal and
| sound isolation.
|
| 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_con
| ductivi...
| mcguire wrote:
| I think the major advantage wood construction has over
| concrete is that individual wood elements are replaceable.
| It would be hard to ship-of-Theseus a reinforced concrete
| structure.
| Arrath wrote:
| Plain reinforced concrete is fine to repair and work
| with. Very basic: Erect temporary supports around the
| area if its load-bearing, saw-cut/hammer out the working
| area, splice and retie any reinforcement, prepare the
| existing concrete surface for a fresh pour, pour and
| cure.
|
| 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.
| capitainenemo wrote:
| What's wrong with wooden houses? Easy to build, easy to
| insulate, in normal circumstances cheap. Far far better for
| the environment than concrete...
| FridayoLeary wrote:
| It does sound a bit weird. How long do they last? In UK you
| would expect a house to remain standing for 80-150 years.
| Maybe more.
| zdragnar wrote:
| I live near one of a state's first cities in the Midwest.
| Many of the original buildings, brick and wood alike, are
| still standing. Those are between 140 and 180 years old.
|
| 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.
| handrous wrote:
| There are whole neighborhoods of 120+ year old wooden
| houses in the US. If they're cared for they look great.
| If they're not, they look like shit but are still
| standing and basically fine as long as water's been kept
| out (no long-term roof leaks). They're largely made of
| WTF-good timber by modern standards, but worse
| construction in other ways (balloon framing is common,
| for instance, and fire protection is otherwise poor as
| well).
|
| 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).
| cp9 wrote:
| I live in one of those neighborhoods and the thing that
| kills our houses (aside from leaking roofs) is poor
| foundations. I've literally never heard of one of these
| houses falling over because of a structural issue with
| the actual timber it's built from. It's either that the
| wood has rotten because of roofing issues or (more
| likely) the rubble stone foundations fell apart
|
| 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.
| baybal2 wrote:
| > Those are between 140 and 180 years old.
|
| Why they are so old? Did owners not have money to
| rebuild?
| cp9 wrote:
| my house is well over a hundred years old and was built
| out of wood, it's been well taken care of (still has the
| original roof, even!), why exactly would I want to
| rebuild a perfectly good building? These buildings have
| been standing a long time, they aren't exactly going
| anywhere
| jazzyjackson wrote:
| "Don't make 'em like they used to"
|
| 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)
| nemo44x wrote:
| My home is 100 years old and probably one of the younger
| houses in the area. Many homes have been renovated in
| part of over time. Things like adding electricity,
| changing the electrical to be modern, adding additions,
| converting rooms and adding modern plumbing, changing
| siding and roofing, HVAC installed, etc. So over time,
| the home is modernized but the original frame (the "good
| bones") are still there.
|
| 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.
| rootusrootus wrote:
| My mom lives in a 110 year old house in one of the
| wettest regions of the United States. The walls are a bit
| thin by current standards, just 2x4 even though it's two
| stories with a basement, but it's holding up fine. Rot
| has never been a problem. She just keeps up on the
| routine maintenance -- painting about every 10 years,
| roof shingles every 25 years. It would still be fine 100
| years from now, I expect, though I'm certain that when
| she passes someone will buy the house, gut it, modernize
| the wiring, plumbing, and insulation, and then rebuild
| the interior to look as original as possible. Very
| popular around this area.
| echelon wrote:
| Wooden homes last just as long. There are many wooden
| homes of that age, and they have a ton of character and
| command steep prices.
| capitainenemo wrote:
| My current home is a dirt cheap one built during the
| explosion in housing post world war II. It's wood on top
| of poured concrete slabs for a foundation (yes, ok, some
| concrete - maybe something else could have been used?
| brick?). It has no structural issues. (it has issues due
| to stupid design decisions from stamping out homes at
| that time, but none related to the wood). It is now 60
| years old. I imagine it will be standing for a long time
| to come.
| calvinmorrison wrote:
| Cinderblock foundations aren't uncommon, brick or stone
| and mortar.
|
| And lots of basements were packed eaeth, a whole nother
| level of 'unfinished'
| michaelt wrote:
| Well, some American states are extremely hot and dry by
| UK standards - meaning issues like rot and rust are less
| of a problem.
|
| 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!
|
| [1] https://goo.gl/maps/de1ZCXtpjS49sSHB7
| kube-system wrote:
| 6 foot between detached single family homes only in the
| densest old city neighborhoods. The legal minimum in most
| places is now 10. These would be properties that many
| Americans describe as "right up my neighbors ass". Your
| average home in the burbs is going to have 30+ feet
| between them, especially in the hot dry (read: developed
| post AC) areas of the US you're talking about.
|
| > 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)
| lotsofpulp wrote:
| > 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).
| kube-system wrote:
| Ah that makes sense in wildfire prone areas. Haven't seen
| it much here in the east.
| jonfw wrote:
| In the southeast it's very popular for new construction.
| You still see a lot of vinyl as it's cheaper though
| netr0ute wrote:
| There's also asbestos siding which is common on older
| houses.
| hanniabu wrote:
| > cement fiber siding like Hardibacker, Durock, or
| Wonderboard
|
| Those are typically are used with masonry siding. Vinyl
| siding is usually put on OBS boards with a vapor barrier
| in between.
| lotsofpulp wrote:
| Interesting, all of the wood frame homes going up in
| WA/OR/CA that I have seen use cement fiber siding.
| hanniabu wrote:
| Wait, they put up these boards with nothing over it? Do
| you have any pictures you can link to see what they look
| like?
| lotsofpulp wrote:
| https://www.youtube.com/watch?v=vNz6MekFesg
|
| It's OSB, then a weather resistant barrier, then the
| cement fiber siding on the outside nailed into the OSB.
| jnosCo wrote:
| Cement fiber is definitely the trend, at least in the
| PNW, but vinyl is still a budget option, and cedar has
| it's place as well.
| genericone wrote:
| And in SF and Daly City, and other 'old affordable
| neighborhoods', no detachment at all.
| irrational wrote:
| Where do you live that vinyl is that common? Where I live
| almost every house has hardiplank or cedar siding.
|
| 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.)
| kube-system wrote:
| Vinyl is the best selling in the US according to a couple
| of searches, and it is definitely very common in the
| eastern US.
| irrational wrote:
| Well, yet another reason never to live east of the
| Rockies ;-)
| anonAndOn wrote:
| My last one was built in 1895. I really miss the 10 foot
| ceilings. The increased air space + transom windows were
| a fantastic passive cooling system.
| handrous wrote:
| Old houses are amazing if you need to live in them
| without modern heating and cooling. They're built to work
| about as well as possible, under those circumstances.
|
| 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.
| rootusrootus wrote:
| I looked at a house in Boston that was built in the
| 1700s, and it had the opposite problem. Ceilings were
| like 6.5 feet, felt claustrophobic.
|
| 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.
| lotsofpulp wrote:
| In an air conditioned house, I do not see the purpose of
| 9ft and 10ft ceilings other than vanity. It just results
| in more cost to condition air that is above your head.
|
| I would rather spend less on my utility bills, and
| conserve the energy.
| rootusrootus wrote:
| I don't feel too strongly about it, though on balance I
| like the open feel to 9 foot ceilings. It seems to be
| standardized on most new houses these days, so unless I
| have another house built I don't expect to be able to
| make a choice.
| RosanaAnaDana wrote:
| I live in a 100 year old wooden house. Its got some
| character due to modifications and its era (1920's). But
| its been well maintained and there is no apparent reason
| it wouldn't survive another 100 years.
| waynesonfire wrote:
| same. and it was built so long ago that the 2x4s used in
| it's construction are actually 2"x4", and probably made
| from old growth.
| rootusrootus wrote:
| My last house was built in 1964 and the wood would be
| considered extravagant by today's standards. It was no
| fancy house, either, just a garden variety ranch. But it
| had decent (as I said, not fancy) oak hardwood
| throughout. Actual 2x4s that weigh 2x as much as fir
| studs today. Old-growth cedar siding. It was built in an
| era where it was no big deal to use good wood for
| everything.
| Scoundreller wrote:
| A lot of codes are directly or indirectly moving to
| whatever size a 2x6 is because of increased insulation
| requirements. For exterior walls anyway.
| bluGill wrote:
| The codes are moving back to 2x4 walls. Since the 1970s
| 2x6 started becoming common, but that reversed when
| someone realized you can put 2 inches of foam outside the
| 2x4, have the same wall thickness (meaning common
| doors/windows fit), and there is no break in the wall
| insulation. The wood itself in a board is not great
| insulation, so the foam around the whole house even while
| it seems to offer the same r value offers more. (you can
| also get foam with r values much better than wood, I'm
| not aware of code requiring that, but some builders offer
| it as an upgrade).
|
| Note that this foam is foil faced meaning it insulates
| against radiation energy as well as conduction or
| convection.
| rootusrootus wrote:
| That must be regional. I live in the PNW, and it's pretty
| temperate here (the last few days notwithstanding...).
| House construction is still 100% 2x6 for exterior (and
| interior load-supporting) walls. Most houses are not
| being built with foam on the outside. I've heard of that
| happening where it's legitimately cold, though.
| bluGill wrote:
| I'm sure it is regional. Close climates need more
| insulation than warmer ones. I've seen variations of this
| in El Paso (only 1 in foam) for high end housing where
| the cooling advantages can be sold.
|
| 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.
| rootusrootus wrote:
| > I doubt interior load supporting walls are 2x6
|
| Could be another regional difference. Our code requires
| 2x6 minimum for load bearing walls.
| CalRobert wrote:
| This works for bigger studs too! The options presented
| for the house I'm building now are 70x200mm (about a
| 3"x8") stud with 200mm interior insulation and 100mm
| exterior. That's for a very well insulated wall, though.
| bluGill wrote:
| It doesn't, the 2x6 "fad" went on long enough that you
| can buy doors and windows sized to that standard. You can
| use any thickness of wall you want, but if it isn't same
| thickness as a 2x4 or 2x6 you will have to put forth
| extra effort to make your doors and windows fit. Use a
| standard dimension wall and you can buy those to fit.
|
| Not a big deal for a qualified carpenter, but enough
| extra labor that you will pay extra for it in addition to
| materials.
| CalRobert wrote:
| Huh, for what it's worth I think 200mm is relatively
| common here. 200mm insulation batts are standard, if
| nothing else.
| CalRobert wrote:
| The UK has wattle and daub wood frame houses that are 500
| years old, too. The hatred for wood frame houses in the
| UK and Ireland is a strange thing, especially considering
| the pyrite scandal a few years back, the mica one now,
| and the hideous carbon footprint of concrete.
|
| 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.
| FridayoLeary wrote:
| Door and window frames are the only wooden element in
| most houses. You can instantly see if they have never
| been replaced, and after 70 - 80 years they look quite
| old. Now imagine the whole house looking like that.
| CalRobert wrote:
| To each their own; I live in a town full of cracked,
| heavily-stained plastered and pebble dashed block
| buildings that look pretty terrible.
| tonyedgecombe wrote:
| _The hatred for wood frame houses in the UK and Ireland
| is a strange thing_
|
| It's not when you consider that we cut down most of our
| trees.
| robertlagrant wrote:
| 13.1% of UK as woodland in 2018; 4.7% in 1905. Not too
| shabby!
|
| https://www.forestresearch.gov.uk/tools-and-
| resources/statis...
| CalRobert wrote:
| Well, cut down, and grazed the rest to oblivion to turn
| the islands in to meat factories.
| pletnes wrote:
| Fire safety is not great. (Many other things are. )
| elric wrote:
| That's an over-generalization which is very often wrong.
| Massive timber (including things like CLT or Brettstapel)
| are very fire resistant and very safe in a fire. The
| outer layers tend to char while the rest of the structure
| is preserved.
| lotsofpulp wrote:
| It is comical how so many seem to think wood and drywall is
| always inferior to concrete.
|
| I would even say it is the opposite, you are lucky to have
| access to cheap enough wood.
| jhallenworld wrote:
| I would rather live in a cheaply made wooden house than a
| cheaply made concrete one. The simple common way to build
| a wooden house is massively redundant. Concrete houses
| use post and slab, even in poor countries. So in Nairobi,
| they were having six building collapses per month.
|
| https://www.csmonitor.com/World/Global-
| News/2016/0430/Why-ar...
| codefined wrote:
| Your source seems to contradict 'six buliding collapses
| per month':
|
| "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?"
| jhallenworld wrote:
| My source for the 6/month figure is this video:
|
| 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...
| yawaworht1978 wrote:
| I think the only advantage wood has it that it can be
| burned for heating.
|
| No seriously, i do not see a single advantage of a wooden
| house. But I am eager to hear.
| jazzyjackson wrote:
| You can change your mind, knock out a wall there, put in
| a new wall here. Basically easier to remodel.
|
| 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.
| lotsofpulp wrote:
| Easy to work with is the main one. I can do almost
| everything myself with less time, less equipment, and
| less chance of injury.
|
| 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.
| echelon wrote:
| They don't waste energy to heat or cool.
|
| 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.
| capitainenemo wrote:
| Easy to insulate, easy to build with, durable, easier on
| the environment.
| stronglikedan wrote:
| The can stand up better to an earthquake.
| Spooky23 wrote:
| Wood is cheaper up to certain scale, less environmental
| impactful, and flexible in the face of dynamic load
| changes and construction.
|
| 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.
| ben7799 wrote:
| Concrete has horrible greenhouse gas emissions issues
| that wooden construction doesn't.
|
| 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.
| ASalazarMX wrote:
| Is there any comparison available? I've seen concrete and
| masonry houses built, and while the concrete has a
| greater carbon footprint, there's little waste compared
| to wood houses with drywall: wood treatments and
| coatings, insulating foam, materials wrapped in
| disposable plastic sheets, etc. Modern wood houses are
| far from just wood.
| ars wrote:
| You don't want to live in a multi-family wooden house - the
| noise from above you will drive you wild. With a concrete
| house you don't hear your neighbors.
| brandonhorst wrote:
| Since moving to Boston I have only lived in multi-family
| wooden houses, and this just isn't true, at least with
| modern-ish insulation. I can occasionally hear my
| upstairs neighbor's dog when she gets excited, and
| precisely nothing else.
| capitainenemo wrote:
| Hm. The only multi-family building I've ever lived in was
| an apartment complex and it was steel and concrete. I
| don't think they are typically built out of wood even
| here, although I've read about some experiments with
| wooden office buildings as more environmentally friendly.
| I guess if I was really curious I could look and see if
| they'd added extra sound damping to deal with that.
|
| In any case, the typical American wooden home is not
| going to have a family above you. :)
| quickthrowman wrote:
| There is a ton of 4 story stick-built multi family
| housing in the US
| lotsofpulp wrote:
| That specific type of construction started in 2009 after
| the building code was changed to allow it. They are known
| as a "1+4" or "1+5", with the first floor being concrete
| and then 4 or 5 wood floors above. Very economical, and
| hence why almost all new multi unit construction has been
| that style for the past decade.
|
| https://en.wikipedia.org/wiki/One-plus-five
| jhallenworld wrote:
| Three deck homes are common in New England, here are some
| examples (I think these are five family homes, the upper
| floors are two families each):
|
| https://www.google.com/maps/@42.2662623,-71.8167462,3a,75
| y,1...
| kube-system wrote:
| I've lived in multi family wood homes in the US without
| issue. It can be an issue with the cheapest construction,
| but sound insulation can mitigate or solve those
| problems.
| JoeAltmaier wrote:
| They're largely right. Only 10% of Americans live in single-
| family homes.
| julienb_sea wrote:
| A cube with 7.71km side length is so totally foreign to us it
| is unimaginable. Mt Everest by volume is 59.5 km^3, or about
| 13% of the volume you've quoted. We are probably more
| accustomed to think about sizes of conical structures, again
| due to mountains being the only thing we have for scale. It
| would be interesting to think how much we'd have to scale up Mt
| Everest in order to get to a volume of 458 km^3.
| jhgb wrote:
| By a factor of (458/59.5)^(1/3), you mean? That seems roughly
| a factor of two to me.
| topspin wrote:
| I've done a similar mental experiment with oil. The US consumes
| about 20 million barrels of oil per day. Here is a useful
| visualization: imagine a (US) football stadium from the air
| with a huge black cube floating above like something from a
| sci-fi movie. The cube is about 50% larger on a side than the
| distance between goal lines. That cube of oil is about how much
| the US burns in a day.
| Aerroon wrote:
| It's kind of incredible how even this "too vast to imagine"
| amount is 'just' a few large mountains.
| phreeza wrote:
| For contrast, all human beings probably fit into a cube of 1km
| side length.
| koolba wrote:
| This is a classic xkcd "what if" topic: https://what-
| if.xkcd.com/8/
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