# Construction cost - steel vs. concrete **URL:** \ **Category:** Factual Questions\ **Created:** [March 31, 2018, 3:07pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528 "2018-03-31T15:07:24Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [March 31, 2018, 3:07pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/1 "2018-03-31T15:07:24Z")
If I am building a 10 story building is it cheaper to have the basic structure steel or concrete? Steel goes up faster but maybe it costs more to buy. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [March 31, 2018, 3:13pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/2 "2018-03-31T15:13:24Z")
Concrete preforms very poorly during earthquakes … the work-around is to sheath the concrete with steel … so if this is a concern, then we might as well build the structure out of steel to begin with … ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [March 31, 2018, 3:21pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/3 "2018-03-31T15:21:13Z")
> [@watchwolf49](#): > > Concrete preforms very poorly during earthquakes … So why are there so many concrete buildings in Japan? They seem to do pretty well there. ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [March 31, 2018, 3:21pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/4 "2018-03-31T15:21:21Z")
an extreme example, the Empire state building was built out of steel in 18 months including tearing down the hotel that was on the site. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [March 31, 2018, 3:50pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/5 "2018-03-31T15:50:54Z")
A 10-storey concrete building would contain a lot of steel in the concrete. ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [March 31, 2018, 3:55pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/6 "2018-03-31T15:55:39Z")
yes I know there is rebar in concrete. I mean a steel frame vs. concrete with rebar. ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [March 31, 2018, 5:05pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/7 "2018-03-31T17:05:02Z")
It may be cheaper for the labor, as steel doesn’t require curing time and the building could conceivably go up more quickly. For concrete, you’ve got to do a lot of form and rebar work, and any utilities have to be in place prior to calling in the mixers. Then there is a waiting period for the initial cure, then the forms have to be stripped and carted off, and the concrete then needs to cure for a few weeks before any load can be placed on it. There are exceptions. You can end up paying for a lot of labor hours during a pour, while workers stand around waiting for the next load to arrive, although a smart contractor will plan for that. As mentioned above, concrete generally has tremendous compressive strength, but poor shear strength. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [March 31, 2018, 6:32pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/8 "2018-03-31T18:32:32Z")
> [@scr4](#): > > So why are there so many concrete buildings in Japan? They seem to do pretty well there. Define “well” … [Image 1](https://www.newcivilengineer.com/pictures/2000x2000fit/3/7/7/1278377_Kobe_Earthquake003.jpg) [Image 2](http://3.bp.blogspot.com/--Ljf_6Jpolw/TY5lusAY-HI/AAAAAAAAAB4/nhggMenD0CM/s1600/Great-Hanshin-Awaji-Kobe-Earthquake-Office-buildingJanuary16-1995.jpg) [Image 3](http://3.bp.blogspot.com/_6Vw-62YnWMs/SmkrBHafS7I/AAAAAAAAAOg/xgwOeK3DXHI/w1200-h630-p-k-no-nu/Kobe,+Japan+Earthquake+1995.jpg) [Image 4](http://www.npo.co.jp/hanshin_e/H950223.jpg) > [@Johnny\_L.A](#): > > A 10-storey concrete building would contain a lot of steel in the concrete. Yes, it would … [Image A](http://cdn.abclocal.go.com/content/kgo/images/cms/LP_QUAKE%20GALLERY_1280X720_08.jpg) [Image B](https://upload.wikimedia.org/wikipedia/commons/9/91/Cypress_collapsed.jpg) ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [April 1, 2018, 2:55am UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/9 "2018-04-01T02:55:40Z")
> [@watchwolf49](#): > > Define “well” … > [Image 1](https://www.newcivilengineer.com/pictures/2000x2000fit/3/7/7/1278377_Kobe_Earthquake003.jpg) > [Image 2](http://3.bp.blogspot.com/--Ljf_6Jpolw/TY5lusAY-HI/AAAAAAAAAB4/nhggMenD0CM/s1600/Great-Hanshin-Awaji-Kobe-Earthquake-Office-buildingJanuary16-1995.jpg) > [Image 3](http://3.bp.blogspot.com/_6Vw-62YnWMs/SmkrBHafS7I/AAAAAAAAAOg/xgwOeK3DXHI/w1200-h630-p-k-no-nu/Kobe,+Japan+Earthquake+1995.jpg) > [Image 4](http://www.npo.co.jp/hanshin_e/H950223.jpg) Anecdotes don’t add up to data. Of course a poorly constructed concrete building will not withstand strong earthquakes. There was a major revision of the building codes in Japan in 1981, as explained [here (Japanese site)](https://www.homepro.jp/taishin/taishin-basic/839/). Buildings built to the new code fared very well in the Hanshin earthquake, as shown in [this report](http://www.lib.kobe-u.ac.jp/directory/eqb/book/11-43/cpt3-1.html) (again in Japanese). ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [April 1, 2018, 3:39am UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/10 "2018-04-01T03:39:25Z")
> [@Bijou\_Drains](#): > > If I am building a 10 story building is it cheaper to have the basic structure steel or concrete? Steel goes up faster but maybe it costs more to buy. You also have to consider local skills. You can put up steel structures in NYC: you can’t really do that in Melbourne. (Well, I mean you _could_, you’d just have to retrain the workforce, or import oil-platform construction staff.) ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [April 1, 2018, 4:01am UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/11 "2018-04-01T04:01:03Z")
I know the Petronas Towers were made out of reinforced concrete; I heard this was due to the huge cost of steel in Malaysia. ---
**Author:** ![Mr\_Downtown](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@Mr\_Downtown](https://boards.straightdope.com/u/Mr_Downtown)\ **Post date:** [April 1, 2018, 4:05am UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/12 "2018-04-01T04:05:35Z")
As you note, concrete frame is cheaper but steel goes up faster. At times in the past, the numbers have been closer together, or possibly even reversed. But almost no tall buildings are steel-framed these days. You see the occasional exception where a developer needs to build quickly for an anchor tenant that’s key to the financing of the project, or where long spans are needed. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [April 1, 2018, 4:06am UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/13 "2018-04-01T04:06:56Z")
> [@DPRK](#): > > I know the Petronas Towers were made out of reinforced concrete; I heard this was due to the huge cost of steel in Malaysia. The [Burj Khalifa](https://en.wikipedia.org/wiki/Burj_Khalifa) is also mostly reinforced concrete. Somehow I don’t think cost was the most significant for deciding how to build the world’s tallest skyscraper in the United Arab Emirates. ---
**Author:** ![Mr\_Downtown](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@Mr\_Downtown](https://boards.straightdope.com/u/Mr_Downtown)\ **Post date:** [April 2, 2018, 3:53am UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/14 "2018-04-02T03:53:04Z")
Let me modify my earlier statement: almost no tall **residential** buildings are steel-framed these days. For office towers, the numbers apparently are close enough in many cities that the advantages of longer spans sometimes counts for more than the issues steel buildings have with soundproofing and structural drift (sway). ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [April 2, 2018, 11:27am UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/15 "2018-04-02T11:27:48Z")
I suppose they need really big pumps to get concrete pumped up 100 floors. Or do they use cranes to lift it up with buckets? ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [April 2, 2018, 12:10pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/16 "2018-04-02T12:10:15Z")
Concrete can be 3D printed. That technology isn’t quite ready for prime time, but it has enormous promise and will likely be a game changer. Because the printer lays down a thin layer of concrete, it doesn’t need a form to pour into. > **[Concrete 3D printer: the new revolution!](https://www.sculpteo.com/blog/2018/01/03/concrete-3d-printer-the-new-challenge-of-the-construction-business/)** > > Concrete 3D printer is a new challenge for the construction business. Construction 3D printing allows building 3D printed structures, houses or even bridges watch a castle being built [![](https://img.youtube.com/vi/DQ5Elbvvr1M/maxresdefault.jpg "3D Printed Concrete Castle") ](https://www.youtube.com/watch?v=DQ5Elbvvr1M) (the part where you actually see the concrete being extruded starts about 2 minutes in) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 2, 2018, 1:42pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/17 "2018-04-02T13:42:41Z")
OK, it can be 3D printed. But why would it be? ---
**Author:** ![FoieGrasIsEvil](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/foiegrasisevil/32/16638_2.png) [@FoieGrasIsEvil](https://boards.straightdope.com/u/FoieGrasIsEvil)\ **Post date:** [April 2, 2018, 1:44pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/18 "2018-04-02T13:44:13Z")
> [@Bijou\_Drains](#): > > yes I know there is rebar in concrete. I mean a steel frame vs. concrete with rebar. Aren’t most taller buildings built with a steel frame with concrete around it? Isn’t rebar used more for concrete road spans and smaller structures? ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [April 2, 2018, 2:23pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/19 "2018-04-02T14:23:50Z")
> [@Chronos](#): > > OK, it can be 3D printed. But why would it be? Potentially faster, cheaper, less wasteful (no need to build a mould then tear it down after concrete is poured and cured), less labor intensive (labor shortage is a big problem in construction). Also, it can allow more complex shapes, like internal cavities for light-weighting. Though most demonstrations I’ve seen are plain concrete, not reinforced. So they would only be useful for small buildings in benign environments. [This](https://newatlas.com/3d-printed-concrete-bridge/51796/) claims to be the first 3D printed reinforced concrete bridge, but the description sounds like it was post-tensioned with steel cables after the concrete was 3D printed. ---
**Author:** ![Temporary\_Name](https://avatars.discourse-cdn.com/v4/letter/t/8c91f0/32.png) [@Temporary\_Name](https://boards.straightdope.com/u/Temporary_Name)\ **Post date:** [April 2, 2018, 5:55pm UTC](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528/20 "2018-04-02T17:55:03Z")
> [@Chefguy](#): > > It may be cheaper for the labor, as steel doesn’t require curing time and the building could conceivably go up more quickly. For concrete, you’ve got to do a lot of form and rebar work, and any utilities have to be in place prior to calling in the mixers. Then there is a waiting period for the initial cure, then the forms have to be stripped and carted off, and the concrete then needs to cure for a few weeks before any load can be placed on it. There are exceptions. You can end up paying for a lot of labor hours during a pour, while workers stand around waiting for the next load to arrive, although a smart contractor will plan for that. As mentioned above, concrete generally has tremendous compressive strength, but poor shear strength. Concrete does not need the full twenty-eight (28) days to be able to strip and work with the material. For slabs, they are often given to other trades after only 24 hours or 48 hours. For structural columns, waiting a week is usually enough time before striping the forms (and storing them to be used again on the floor above), but you cannot put a full live load on it for 28 days. For the most part, concrete continues to harden forever—or until it starts to crumble. It is engineered to reach a certain hardness (measured by drilling a core and putting it into an industrial press) after 28 days. On many jobs they will pour cylinders from each truck of the pour which are crushed later and the amount of force needed to crush it is recorded within the building permit paperwork. (For a fact the contractor keeps a record so a subsequent disaster cannot be blamed on cheap materials.) I am aware of a building where two concrete trucks showed up at the same time, one carrying 3,500 psi mud for structural columns, and the other 2,500 psi mud for a sidewalk. Of course the trucks were sent to the wrong portion of the job and the contractor had a sidewalk you could drive tanks on (well, not quite- but you get it) and structural columns not quite built to snuff. Inspectors were insisting the contractor jackhammer out the columns and set to re-pour. The contractor was going to lose his business over this mistake. The architect stepped in and made a suggestion; let the columns cure for twenty-eight days, then do a test on the cylinders. The inspectors insisted the actual columns be cored; they couldn’t trust the cylinders test. At the end of the month, all of the samples exceeded the required 3,500 psi. With reference to the last sentence of your post, concrete does have great strength in compression. It is also okay for shear if it is well designed (a blank wall with no openings is very strong in shear as long as it has enough steel to not crumble, but a twenty foot wide wall with a seventeen foot opening in it [say for storefront glass] has almost no shear strength- you would have to put a steel moment frame behind it with steel cables criss-crossing it. You may also pick up shear from the roof if it is a strong enough diaphragm. By and large, as long as you have a good six feet of solid wall on each end of the wall and the opening isn’t larger than the two side panels combined—it will work on any single story building as long as there is enough wall above the opening.) Where concrete is weak is in tension. If you pour a bench out of concrete in the middle of a floor, it would require jackhammers or bulldozers to remove. If you poured a long concrete arm to hang from the concrete ceiling/roof above with a cubby at the bottom to hold only fifty pounds (at any distance above the floor except zero), you only have to wait for the first strong breeze for it to come down. Compression is crushing something together- and concrete is strong in that condition; tension is pulling something apart—concrete is very bad at this, very weak. A half inch steel rod can carry more weight than a giant concrete column hanging from above. Shear is racking side to side—concrete can be okay at this depending. > [@Chronos](#): > > OK, it can be 3D printed. But why would it be? Not exactly 3D printing, but I know of one application where thin layers of concrete are used to build HUGE structures with no support in the middle. If you Google dome construction you can see some examples. What they do is build a giant balloon the size and shape of the building they want to build. They then pour a foundation to support a structure that size and build in anchors to hold the balloon down. Then the builder must use multiple high volume jet fans (using multiple sources of power) to inflate the balloon. They have to get it steady and perhaps build airlocks so the balloon stays the same exact shape for months. The outside of the balloon is treated with weather proof Mylar or similar material. The inside is course enough for stuff to stick to it, and the first step is to spray a thin layer of foam inflation onto the inside of the balloon and add depth sticks (if the insulation is to be 6” they stick 6” dowels into the first layer of foam about every sixteen inches or so. They also place steel tie wire into the foam on a prearranged pattern to match where the rebar will go. They can build these as big as gymnasiums, so it may take multiple crews on lifts to put on just the first coat. Then day after day they spray foam that looks like the spray can stuff you can buy at Home depot. As they get close to the six, or eight, or twelve inches of insulation they are trying to achieve, they kind of trowel the surface smooth so there is a more or less smooth break between insulation and structural material. They can also use a handsaw to trim back any place within the foam that became too thick. It may then take quite a while to build a whole rebar dome three, or four, or six inches away from the foam insulation depending on if they are trying to be in the middle of a six, eight, or twelve inch thick layer of concrete. I understand even #5 rebar will hang from the foam, but I would be very careful under that at first. They pre-bend the steel to match the place in the dome it is meant to occupy. After all the horizontal pieces are hung in place on the correct centers (usually about 16 or 24 inches apart from each other), they can fairly quickly place the verticals and start tying them off. The inspector signs off on the steel and they start spraying thin layers of concrete at the top of the dome. First layer is supposed to be about a ¼ to 3/8 inch thick. Every day they add a new layer, after a few days they can apply thicker coats. They must be sure to leave no voids behind the rebar- hollow spots are not tolerated! Depending upon the size of the structure, they can sometimes turn off half the fans after just a week. By the time the rebar is completely hidden they can always turn off half the fans. All of the fans are pulled off before the final concrete coats—it has become a self supporting structure at that point. On the final coat they bring floats and or trowels to give a nice finish and blend the whole interior into a nice consistent surface. They are supposed to be only slightly more expensive to build, and require no maintenance ever. Paint the inside every now and then and that’s it. They are also bullet proof, so ideal for school buildings. [Next page](https://boards.straightdope.com/t/construction-cost-steel-vs-concrete/811528.md?page=2)