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RE: CMU California Practice in the 1950's

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The practice of solid grouting all the cells of CMU in California is variable.  The practice stemmed to the studies on CMU seismic resistance done in the 1970's and 1980's time period.  For whatever reason, the researchers at the time only tested walls that had each cell grouted regardless of whether or not there was vertical reinforcing in the cell. 
Code developers never made solid grouting a requirement, but it became a common practice.  Many practitioners in California specify only rebar for horizontal reinforcement and solid grouted walls.  The reduction in mass was not perceived as important as the added perceived continuity of a solid grouted wall.  And the joint reinforcement is not considered as consequential.  Again, the practice is not totally uniform in California, but it has been very common. 
I performed a very unscientific survey on this list a while back and most respondents agreed that solid grouted walls in California were the norm.  Once the state line was crossed, the practice of using partial grouting was more common. 
It became so pervasive that many masonry contractors in California did not know to use lath or joint reinforcing for horizontal reinforcement.  I recall working on a large project in Los Angeles in the late 1980's and the masonry contractor did not know how to construct a partially grouted wall.  He did not know how to use the lath on the ungrouted cells, and he did not know how to install wire reinforcement in the bed joints.  I gave up trying to explain it and went to solid grouting and rebar only for the horizontal reinforcement. 
Anyway, that experience is what precipitated the inquiry to a project constructed in the early 1950's. 

Regards, Harold Sprague


From: sgordin(--nospam--at)
To: seaint(--nospam--at)
Subject: Re: CMU California Practice in the 1950's
Date: Sun, 26 Apr 2009 13:04:13 -0700

My experience is the same, I am not aware of any practice of using only solid-grouted walls, other than for the earth-retaining or fire-rated purposes.
V. Steve Gordin, SE
Irvine CA
----- Original Message -----
From: Bill Allen
Sent: Sunday, April 26, 2009 12:47
Subject: RE: CMU California Practice in the 1950's



I know the preference for open end blocks which means grouted cells are really grouted double cells, but I'm curious if this is true.


After all, grouting solid is a heavier wall producing more force at the tie at the top and increasing the load on the diaphragm. If bars are only required at 48" (#4 @ 24" or even #5 @ 32"), that means half the wall can be un-grouted providing quite a bit of reduction in mass transferred to the roof diaphragm.


I've designed quite a few block walls grouted at steel only, all of them since 1980. I'm wondering if I'm out of step with standard practice. Of course, it wouldn't be the first time.


T. William (Bill) Allen, S.E.


Consulting Structural Engineers
V (949) 248-8588 F(949) 209-2509

I know that it has been the general practice in
California to grout CMU walls solid since at least the 1980's. 

Regards, Harold Sprague

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