Control joints (CJ) for a CMU wall

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aagangchen

May 07, 2022 15:06

An architect is working with a structural engineer to layout the control joints (CJ) for a CMU wall. They successfully layout all the CJ according to the CMU block module. Which of the following cannot be a CJ-to-CJ dimension in this wall’s CJ layout? Why?

1. 21’-4”
2. 20’-8”
3. 19’-8”
4. 22’-0”

Gang Chen, Author, AIA, LEED AP BD+C (GreenExamEducation.com)

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  Bankole Folorunso May 07, 2022 16:35

  I would say #3, because it would involve cutting CMU in an inefficient way. It can be time, cost and labor intensive too I think.

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  David Grussgott May 07, 2022 20:36

  20'8

  follows the CMU block module

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  aagangchen May 14, 2022 04:09

  The answer is c. 19’-8” because it is not set up per CMU block module and will require the cutting of CMU blocks and cost more money. The trick to set up the CJ-to-CJ dimension is if the feet is an odd number, then the inch must be 4”, such as 3’-4”, 15’-4”, etc. If the feet is an even number, then the inch much be 0” or 8”, such as 8’-0”, 12’-8”, etc.

  Gang Chen, Author, AIA, LEED AP BD+C (GreenExamEducation.com)

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