Talk:Concrete masonry unit

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Correct international wikilink[edit]

The german wiki article Betonwerkstein links to this article. There it´s described as every kind of concrete product with a processed surface. I really do not believe that this plaster-like stone is a cinder block (Specs (pdf)). Is there any techical term for this product or does it has to be paraphrased ? -- 21:04, 1 February 2006 (UTC)

  • The Construction Specifications Institute in the US has a list of many surface finishes for concrete block. -- Dogears 02:36, 7 February 2006 (UTC)
04 22 00 Concrete Unit Masonry
04 22 00.13 Concrete Unit Veneer Masonry
04 22 00.16 Surface-Bonded Concrete Unit Masonry
04 22 19 Insulated Concrete Unit Masonry
04 22 23 Architectural Concrete Unit Masonry
04 22 23.13 Exposed Aggregate Concrete Unit Masonry
04 22 23.16 Fluted Concrete Unit Masonry
04 22 23.19 Molded-Face Concrete Unit Masonry
04 22 23.23 Prefaced Concrete Unit Masonry
04 22 23.26 Sound-Absorbing Concrete Unit Masonry
04 22 23.29 Split-Face Concrete Unit Masonry
04 22 33 Interlocking Concrete Unit Masonry

Move article[edit]

How are these related to "Besser blocks?" Is Besser block a brand name for concrete blocks? Australian and UK sites seem to refer to Besser blocks a lot. Images of them look a lot like what are called either "Cinder" or "Concrete" blocks in the US.Davidresseguie (talk) 01:29, 2 November 2009 (UTC) "Besser" is the brand name of a manufacturer of the machinery that is used to manufacture CMU.

Are these called "cinder blocks" in the UK currently? In the U.S., cinders were added to concrete in the time between the wars to save money on materials. Cinder blocks are too brittle and do not support as much weight as full concrete blocks. The term is still used by (older) homeowners, but you couldn't but a cinder block if you tried. Is this the same elsewhere? In U.S. architecture and construction these are specified as "CMU" and called CMU or "concrete block" on the job site. Is "CMU" used anywhere else?

  • Proposal: move this document to "Concrete block" and come to agreement on the first sentence, e.g.:
Concrete block, "Concrete Masonry Unit" (CMU) or "breeze block" (mistakenly called a cinder block), is a rectangular block or brick used in construction. -- Dogears (talk) 23:27, 26 March 2006 (UTC)

I think I completely agree. But it'd sure be nice if we could find a reliable external source to cite on the terminology. —Steve Summit (talk) 12:21, 18 September 2006 (UTC)

Call them what you want but I think that cinder block is the correct term used by young and older construction workers (in the United States of America) for "lightweight concrete blocks". If you have ever picked up a real concrete block you will know without a doubt the diffrence. Real concrete blocks are way heavier than cinder blocks and I rarely see real concrete blocks anymore mabey for footings. Also lightweight blocks (aka cinder block) retain the same structural, fire and insulation properties as regular blocks. From what I have known and read lightweight blocks cost more not less to manufacture but in turn cause less medical bills. If I had to I would call a cinder block a cmu block which would become part of a unit of blocks, mortar and bar to make a CMU. Sorry I don't have references of this information it really doesn't matter to me what you call it but lightweight blocks are often made from cinders and cinder like materials. Greeneyes702 (talk) 23:10, 4 December 2007 (UTC)

In the UK, AFAIK, lightweight concrete blocks used to be made as cinder blocks but are now usually aerated concrete. "Breeze block" is a term that essentially means a cinder block but has, unfortunately, become widely used for concrete blocks in general. So, I'd amend the proposed lead to say something like:

A concrete block or Concrete Masonry Unit (CMU) (often mistakenly called a "cinder block" or, in the UK, a "breeze block"), is a rectangular block used in construction.

We should then restructure the remainder of the article with subheadings to talk about the various types of block: by material (high/low density, with the latter mentioning aerated and cinder blocks) and by shape (solid blocks, those with cavities to allow either reinforcement or insulation to be added to the wall, those with insulation already present either internally or as an external layer), etc. Casper Gutman (talkcontributions) 23:25, 4 December 2007 (UTC)

It's not a mistake there are breeze blocks and there are cinder blocks and they are concrete masonary units. Aerated block (i think) uses a additive the air rises out of then they cut the block and drill holes in them. However many still use molds and presses to make the shape. I would add the info on diffrent types but I do not think it a mistake to call one a cinder block which are usually lightweight made with a aggregate that is cinders or similar material instead of a regular concrete block made from rock/stone aggregate. —Preceding unsigned comment added by Greeneyes702 (talkcontribs) 23:51, 4 December 2007 (UTC)

A user above stated that it was now difficult if not impossible to buy cinder block in the US. I know true breeze blocks are no longer sold in the UK (see e.g. here). Of course, they will still be encountered when working on older properties but nine times out of ten the terms are misused. I personally had an experience working for a structural engineers in the UK where a client was very unwilling to accept a design involving concrete blockwork for an external wall -- he'd mentioned to a friend that "breeze blocks" would be used, and the friend (presumably thinking he meant true breeze blocks) helpfully told him the engineers didn't know their job and breeze blocks would not be sufficiently weather-resistant. The client was most unwilling to believe the blocks to be used weren't breeze blocks -- after all, he'd been abusing the term that way forever.... Casper Gutman (talkcontributions) 01:00, 5 December 2007 (UTC)

Since breeze and cinder are terms used to describe lightweight concrete blocks they are somewhat unnecessary. I was however able to find a dealer selling breeze block but was unable to add them to my cart. one here. Where I am I can walk into most any dealer and ask for cinder block and they know I mean lightweight block 8x8x16 (length twice height). Calling them lightweight concrete block is probably the more proper saying. Greeneyes702 (talk) 02:52, 5 December 2007 (UTC)

We don't use cinder blocks...[edit]

We do not use cinder blocks in the construction industry. We only specify concrete blocks or CMUs. I think the name 'cinder block' has hung around because it rolls off the tongue easier than concrete block. Also, a lot of older homes do have cinder block foundations. I've seen a number of them that are crumbling - so homeonwers know what to call it.

Cinder blocks and concrete blocks look very different - so they are easier to spot. A concrete block looks very dense and solid and a cinder block looks very porous and full of voids.

--Ftw 12:57, 29 June 2006 (UTC)

Just to add to the confusion:
"In 1917, Straub patented CinderBlox, the first concrete masonry unit (CMU)." [1]
So an early manufacturer of what they themselves describe as concrete blocks (CMUs) marketed their product with a name that sounds a lot like "cinder block." It's probably just a mess; I've heard all sorts of different products called all sorts of things.

The aggregates used in making lightweight concrete blocks are often coal cinders or something similar. This is the reason I call them cinder blocks. Greeneyes702 (talk) 23:20, 4 December 2007 (UTC)

This article is disappointing. I wanted to find out more about what cinder blocks are and how they're used in the US, esp. NJ. The Merriam-Webster definition of cinder block is "A block that is made of cement and coal cinders and that is used in building." But either M-W is way wrong, or this article is describing something completely different. The article doesn't relate to what a layperson, in the US, describes as cinder block. Why is a cinder block grey when concrete is light brown? What are blocks that are ubiquitous in NJ construction sites? Why don't we hear of "concrete blocks"? I'm a graduate engineer with long ago experience as a Civil Engineer (USAF) and I'm pretty up-to-date, Cinder blocks should be straight forward -- why isn't there a cinder block article? Tenafly11 (talk) 22:39, 17 November 2014 (UTC)

cinder or concrete -- that is the question[edit]

I'm starting to get the impression that this article is really about concrete blocks, and that its parenthetical about "mistakenly called concrete blocks" is just wrong. I'm starting to get the impression that the bricks that were once called "cinder blocks" are no more, and that what people call "cinder blocks" today are really concrete blocks. Perhaps the obsolete bricks this article calls "clinker bricks" are the ones that were once called "cinder blocks". (Note, however, that the bricks described at the clinker brick article are quite different than this article describes.)

The cinder blocks I can buy today (in the U.S.) probably do weigh about 18kg, just as this article says "concrete blocks" do. (They are, however, still quite cheap.)

I'd rework the article to say all this, but I'm just not sure. I can't find any independent information about any of this on the web. The National Concrete Masonry Association's website (linked to from this article) is useless.

Steve Summit (talk) 03:48, 18 September 2006 (UTC)

Okay, here's one halfway-decent link:

You are right; they are concrete block, CMU, and have no "cinder" in them, at least in modern US construction. I will start the changeover. --Justanother 21:00, 30 October 2006 (UTC)
OK, did the deed. I looked on Google for present-day use of cinder but did not have much luck. Is it still used? Can someone add a bit about cinder, perhaps historical? --Justanother 21:43, 30 October 2006 (UTC)
I'm sure the same situation applies in the UK: breeze blocks (the same as cinder blocks) are no longer available, as their role in providing lightweight construction blocks has been filled by aerated concrete blocks. However, the term is widely used by the general public to refer to concrete blocks in general. I think it's probably useful to have cinder/breeze block redirecting here, but the lead should reflect the differences between the different types of block and the fact that the terms are often confused as many readers will arrive here by typing breeze/cinder block when they mean concrete block! I added a reference with more info on the UK situation Casper Gutman (talkcontributions) 15:05, 30 November 2007 (UTC)

Cinder is a term for an ash leftover from burning coal, and Cinder Block were made by a process of mixing this cinder with cement and then turning the mix into hollow-core blocks. The material behaves a bit differently than concrete blocks, but there's little to no modern testing on the material because the coal companies improved their burning techniques and cinder was no longer produced as a by-product, and cinder blocks disappeared shortly after. Best guess on the timeline for the cinder block's demise was in the 1960's. A fellow named Francis Straub patented the cinder block process in 1913. references:,6503480 - Perrin Ehlinger, AIA — Preceding unsigned comment added by Scupperer (talkcontribs) 15:25, 22 April 2011 (UTC)

I can remember when I was a child in the UK in the 1960s my family had an extension to our house built with breeze blocks. I was told at the time they were made out of power station 'slag'. They were dark blue-grey in colour and visibly very porous. I suppose it stuck in my mind because to a child they seemed weird, and nothing like normal bricks. (talk) 18:19, 27 May 2015 (UTC)


It would be nice to have a chart of standard CMU sizes in this article. Anyone? —The preceding unsigned comment was added by (talk) 15:06, 8 April 2007 (UTC).

I also believe it would be helpful to mention their modularity with brick sizes. In the US one CMU block is both the same width and depth as two bricks plus a mortar joint.
Width CMU 15 5/8 in. = (2)Brick 7 5/8 in. + (1)Mortar 3/8 in.
Depth CMU 7 5/8 in. = (2)Brick 3 5/8 in. + (1)Mortar 3/8 in.
Anyone have any insight on how this works in other countries? Ahp378 (talk) 14:04, 2 November 2011 (UTC)


When were they invented? And when did they come in to common usage?

--According to family lore, my great great grandfather, Luke Thomas Lowe of Bristol Tennessee held patents for a "cinder block" molding process, along with patents for other inventions. I did not want to add it to the article, but if anyone has the ability to do research, or could point me in the right direction, it would be great. Obviously this patent has long since expired, but apparently an original "mold" still exists in my great uncle's care. 01:15, 21 September 2007 (UTC)Jeffrey A. Haines

E-How has a very good article on the history of concrete blocks with timeline and names, about both solid and hollow-core blocks, which I can't link because of wikirules. Anyway, according to the article, hollow core concrete masonry units (Today known as CMU) were first patented in 1900 by Harmon Palmer, but I've heard that they were around earlier, but often custom molded and poured on site at jobs since about 1880. Palmer was just the first one bright enough to patent the idea, mass produce, and license. — Preceding unsigned comment added by Scupperer (talkcontribs) 15:10, 22 April 2011 (UTC)

- Perrin Ehlinger, AIA — Preceding unsigned comment added by Scupperer (talkcontribs) 15:11, 22 April 2011 (UTC)

Removed Links to Manufacturers[edit]

This is not a billboard. Because this article is about a non-proprietary technology or product, links to product literature are not appropriate, and therefore I have removed several links to the websites of concrete block manufacturers that I found on here. If this were an article about a specific product which is uniquely produced by one company, then a link to that company's website would be appropriate. However, linking to a manufacturer of "concrete block" from a "concrete block" article is far too general. That would be no different from a cookie manufacturer linking to their webpage from the "cookie" article, it would be blatant solicitation, and would fill up the article with irrelevant information.


I'm not sure what value the 3rd and 4th photos are adding to this article, and maybe even the 2nd. They show construction that includes CMU's, but don't really illuminate anything about how they are installed or designed. Does anyone have a picture of speed blocks being installed, or of a half complete reinforced wall clearly showing rebar? I think these would be more valuable. Steve CarlsonTalk 06:17, 9 February 2008 (UTC)

Text from "See also"[edit]

Someone added the following to the "see also" section. It doesn't belong there and I don't have time to figure out how to fit it in better just now, so I'm removing it to this page for consideration. Anyone?

fine gravel aggregate a.k.a. screenings is a large portion of the mix design in a cmu using upwards to 75% screenings and 25% sand i would also like to give you a list of standard u.s. sizes which when ordering or measuring its width height length 8 8 16 is the standard 8 8 8 also knownas a half block 8 8 16 knock out or bondbeam is used to run your rebar through the courses they have a notch "knocked out" of the top, 8 4 16 or a half high a.k.a a 4" cut

Misleading information[edit]

The following section:-

When the rebar running vertically through a concrete block wall is anchored, as is usually the case, into the foundation or floor slab before the wall is built, it presents a potential problem in assembling the wall, since every block might need to be lowered from the rebar tops to its resting place in the wall. This problem is solved by using a style of open-ended block whose plan form resembles the letter "H", commonly known as a mortarless head joint or speed block. Speed blocks can be maneuvered between the reinforcing bars and tilted into place; the vertical spaces are then filled with concrete as with ordinary Concrete blocks.

Is totally misleading, of course rebar is anchored. What's the point otherwise? Lap joints in rebar have been around since the first reinforced concrete, are we expected to have full height vertical bars set into the foundations? .

After using this method of construction for over forty years I have never heard of let alone seen glazed modular blockwork. I think this section should be removed or the poster cite some references. Glazed brickwork - yes but (in Victorian era buildings prior to cheap ceramic tiles), but not these things. billbeee (talk) 12:32, 3 April 2008 (UTC)

Casper Gutman (talkcontributions) 08:57, 19 March 2008 (UTC)

breeze blocks[edit]

"breeze blocks" were not so called because breeze is a synonym for ash. They were called breeze blocks because they were used to build breezeways.

why on sizes?[edit]

Didn't see a answer to why standard sizes/dimensions were chosen. Isn't this a fundamental question? Why are concrete blocks so thick as opposed to standard bricks? Why the need for air space in concrete blocks and not standard bricks? Etc... Rtdrury (talk) 01:05, 6 June 2014 (UTC)

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Lower density blocks may use industrial wastes as an aggregate. (talk) 11:03, 4 July 2016 (UTC)