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CMU's


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I Inspected a house yesterday that used 8x24 block for the foundation, some of which were cast to look like limestone.

The literature stated that it was built in 1895.

I realize that CMU's change by locale, but I've never seen this size before.

Anyone have any info?

I'm reporting that I feel the house was built in the late 1920's for a host of reasons including the block.

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By the late 1920's block was pretty much standardized as 8x16. As Bill said, there were forms to produce block in the late 1800's. Sizes varied quite a bit, and odd stuff was not uncommon.

In 1895 it is still common to see some cut nails used for framing. I look for construction features (gas piping, nails, etc.) to try and get an idea of age.

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The ashlar face block was 8x16.

Wire nails.

Stamped, not cast butt hinges

No gas piping holes

Nicely milled and planed joists and sub floor

The rest of the place was covered in drywall and vinyl. It always reminds me of a corpse in a coffin. The person looks something like they used to, but they're not the same and there's no going back.

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...a neighbor of mine (civil engineer married to another one) built part of a house and garage with site-made CMU's they made by hand with wood slipforms and field stone, which were exposed on a face, 8x8x16. Heavy as could be and masons who laid them cursed the heavens, but they look ok after all.

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Chad,

I was reading some old publications about block the other day. From what I read, some blocks were being produced on a very limited basis as far back as about the 1850's, but not much as all until at least 1900. Seems like about 1906 was the real beginning of the industry. I save a few references to blocks about 8 to 10 inches by 24 to 32 inches long. The standardization came about in the 1920's.

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Here are a couple of good references:

Concrete-Block Manufacture-Processes and Machines

the manufacture of Concrete Blocks and their use in Building Construction

both published in 1906, written by H.H. Rice. Copies are on the web.

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  • 5 years later...
On 8/18/2016 at 3:45 PM, Chad Fabry said:

They look heavy.

They no doubt are heavy, which reminds me of concrete block made by Superior out of Frederick, MD. Their 8 × 12 × 16 concrete blocks were very dense using pretty consistently fine aggregate and more than average cement. The block were so hard that they would actually ring when tapped with a hammer. They tipped the scale at probably close to twice the weight of a Solite concrete block and could therefore not be set in place with one hand.

Installing exceptionally heavy concrete block is an isometric exercise because you can't simply place the block on the mortar bed without squirting the mortar out from under the block. The unit needs to be carefully eased down onto the mortar bed with a slight pause as you cut the mortar vrom the faces. This gives the block time to absorb some moisture from the mortar, which stiffens the bed enough to bear the weight. It's a workout!

Edited by mgbinspect
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On 8/18/2016 at 7:21 PM, Bill Kibbel said:

Split-face block aren't patterned with a form. It's manufactured by "splitting" a large block into 2 blocks leaving 2 rough faces.

And, they were awfull to install because they rarely split squarely. (The split faces often would not generally align with the plane of the masonry wall surface. They really needed to be dressed much like stone often is before being installed, but no one ever permitted the extra time needed to do so.) For this reason, I hated working with split-faced block. To me it looked unfinished.

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On 12/30/2021 at 8:14 AM, mgbinspect said:

They no doubt are heavy, which reminds me of concrete block made by Superior out of Frederick, MD. Their 8 × 12 × 16 concrete blocks were very dense using pretty consistently fine aggregate and more than average cement. The block were so hard that they would actually ring when tapped with a hammer. They tipped the scale at probably close to twice the weight of a Solite concrete block and could therefore not be set in place with one hand.

Installing exceptionally heavy concrete block is an isometric exercise because you can't simply place the block on the mortar bed without squirting the mortar out from under the block. The unit needs to be carefully eased down onto the mortar bed with a slight pause as you cut the mortar vrom the faces. This gives the block time to absorb some moisture from the mortar, which stiffens the bed enough to bear the weight. It's a workout!

A mason told me long ago that 12" block were called "birth control" block because no mason could summon the energy for conjugal activity after a day laying them.

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