Thread: How long have CMU's been around?

Had a seller at the inspection today whom suggested that the 8x8x16" CMU foundation on his 1936 Western Washington home was original. Seems too old to be true & I couldn't find any historical data online. Anyone have a origination date for this area?

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Originally Posted by Luc V. L.

Had a seller at the inspection today whom suggested that the 8x8x16" CMU foundation on his 1936 Western Washington home was original. Seems too old to be true & I couldn't find any historical data online. Anyone have a origination date for this area?

8x8x16 CMU were being used in Miami in the 1910s and 1920s.

http://www.google.com/url?sa=t&rct=j...GifrvDLyQfYvsw

Nice.

Nice, Mr. Peck.

Originally Posted by Jerry Peck

8x8x16 CMU were being used in Miami in the 1910s and 1920s.

I have seen them in similar aged homes in Denver.

Concrete blocks have been around since the early to mid 1800's.

The house in the photo is circa 1870 and block was used.

Agreed, "concrete block" about 1830. "CMU" not until mid 20th century when the engineers and inspectors got involved and needed a fancier term.

Originally Posted by Benjamin Thompson

Agreed, "concrete block" about 1830. "CMU" not until mid 20th century when the engineers and inspectors got involved and needed a fancier term.

"Concrete block" when each factory made their own sizes.

"Concrete Masonry Unit" (CMU) when they agreed on a 'standard size' for the block, i.e., 8" x 8" x 16" (less 3/8" for the mortar joint), thus the "standard" CMU is 7-5/8" x 7-5/8" x 15-5/8", and set with "standard" 3/8" mortar joints the 'installed size' becomes 8" x 8" x 16" (give or take because the 3/8" mortar joints are allowed to vary to make up for slight size differences in the actual CMU size).

As I recall, the 3/8" mortar joint is allowed to vary by 1/8", resulting in mortar joints from 1/4" to 1/2", but the overall wall height and length should average out to be that based on 3/8" mortar joints.

If the mason is using 1/2" mortar joints for all of the joints, the wall is not going to be laid such that it comes out with the openings where the openings should be, and the height will not be the correct height either.

I remember growing up they were called cinder block and did contain cinder. Lots of the block would have rust spots due to metals left in the cinder.

Originally Posted by Jerry Peck

"Concrete block" when each factory made their own sizes.

"Concrete Masonry Unit" (CMU) when they agreed on a 'standard size' for the block, i.e., 8" x 8" x 16" (less 3/8" for the mortar joint), thus the "standard" CMU is 7-5/8" x 7-5/8" x 15-5/8", and set with "standard" 3/8" mortar joints the 'installed size' becomes 8" x 8" x 16" (give or take because the 3/8" mortar joints are allowed to vary to make up for slight size differences in the actual CMU size).

As I recall, the 3/8" mortar joint is allowed to vary by 1/8", resulting in mortar joints from 1/4" to 1/2", but the overall wall height and length should average out to be that based on 3/8" mortar joints.

If the mason is using 1/2" mortar joints for all of the joints, the wall is not going to be laid such that it comes out with the openings where the openings should be, and the height will not be the correct height either.

Yep, pretty much the same thing I said with more detail

Cinder block and Concrete block are two different animals I believe. Cinder block is not intended or approved for structural use.

Originally Posted by Dan Cullen

Cinder block and Concrete block are two different animals I believe. Cinder block is not intended or approved for structural use.

You're correct they are two different things.....

Originally Posted by Dan Cullen

Cinder block and Concrete block are two different animals I believe. Cinder block is not intended or approved for structural use.

But it was used back when my dad was a kid. I remember him telling of going down to the Union Carbide plant, which was just down the street, and getting white wash instead of paint. If you lived in a cinder block house you couldn't afford paint and white wash was a bi product of carbide production. He also used to hop trains to through coal off so they could have heat in the winter. Guess things aren't so bad after all .

When I was a kid we were so poor that if it weren't for the holes in my pocket I would have had nothing to play with.