CMU Block control joint question

[Ben29]

I am struggling with ideal location to put the 8" CMU block control joint in this wall.

Should I locate them at the green lines or pink lines?

Pink line spacing is 29-5 1/2" apart.

Green line spacing would leave a 5'-4" wide masonry panel between the tall parapet walls.

My gut is telling me to locate it at the green line due to the jump in wall height.

The brick hatch is real brick veneer. The 5'-4" area between the brick veneer is 1-3/16" thick adhered stone cladding.

 

[JedClampett]

First of all, why aren't the joints spaced at CMU coursing? You're dooming the CMU installers to a lot of cutting. You might have to work with your architect to get that.
But I would use the wider spacing. Thirty feet should easily work according to all the documents I've seen.
Separately, since the brick moves different, you possibly need to space the brick joints more often.

 

[dik]

5'4 is a masonry dimension (imperial?) and in 24', they would likely 'stretch' the 1-1/2", and I'd put them at the green lines.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[XR250]

Pink or every other green is my vote. The brick does not need CJ's at that width.

 

[dik]

each second green as XR notes is good, too. Less chance for water penetration.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Ben29]

I read alot of conflicting info regarding joints.

1) "expansion joints" for clay brick veneer; 25' max spacing in walls with no openings; 20' max spacing in walls with openings
2) "control joints" for CMU block structural wall; 25' max spacing (or 1.5x the wall height)
3) "control joints" spacing can be increased if you provide horizontal joint reinforcing. This is horizontal reinforcing above and beyond the typical ladder joint reinforcing at 16"o/c.
4) The company I previously worked for would typically specify 40'-0" max control joint spacing for CMU block. I am not sure where they got this from. I did find a TEK note from April 2008 from NWCMA which did specify a 40ft maximum control joint spacing. (Northwest Concrete Masonry Association)
5) per TEK 10-02D, we should provide control joint placement at changes in wall height (thus supporting the location of CJ at the 'green line' shown in the drawing)
6) brick veneer joints need not align with CMU wall joint as long as you have cavity wall construction
7) CMU veneer control joint spaced at 20' max (or 1.5x the wall height); needs horizontal reinforcing at 16"o/c

 

[phamENG]

I read alot of conflicting info regarding joints.

Is it just me, or do none of those conflict with one another? Some may be more or less restrictive than others, but those are generally tied to specific situations (changes in height, additional reinforcement, etc.).

I agree with the every other green camp. Part of me wants to put one at an opening, but off the cuff it seems like that would be worse than every other green line.

 

[Ben29]

pharm: your advice to put one at every other green line (and not every green line) conflicts with point #5 above. Also this would put the spacing at ~29', which conflicts with point #2 above.

From what I read, unless you are putting bond beams at 2ft o/c, your control joint spacing is limited to the lesser of 25ft or 2.5x height of CMU. (TEK Note 10-3)

 

[phamENG]

Bern: but not #4, so if you increase reinforcement you can stretch it a bit further. And you don't need bond beams at 2ft o/c.

Instead of trying to use rules of thumb, why not do an analysis? Calculate the actual stresses in the material and reinforce accordingly? TEK 10-1A gives the necessary coefficients to determine the physical shrinkage.

 

[jerseyshore]

Bond beams at 2' o/c? What psycho came up with that idea. Just make the wall concrete.

 

[MotorCity]

I'm going rogue with the "every other green" camp and voting every green line because:

1.The different heights seals the deal for me. I think you're asking for trouble by not providing one at each height change.

2. Different materials, different rates of expansion/contraction. Brick veneer and adhered stone are vastly different animals.
Draw a line between 'em.

3. The joints would essentially be invisible to the untrained eye. They would simply appear as a natural separation between the brick and stone.

4. Disclaimer: Disregard all of the above if a joint at any location negates arching action that you are relying on.

(PhamENG, I see what you did there. "Bern".)

Motorrcity

 

[driftLimiter]

Bond beams at 2' o/c? What psycho came up with that idea. Just make the wall concrete.

Say hello to my little friend, special masonry shear walls. Depending on the wall length and height I do see this and sometimes tighter required spacing of horizontal reinforcement. We always solid grout CMU walls out here, never designed a partially grouted one.

 

[JAE]

Maybe I missed it but is there a change in the face of these walls? If the narrow 5'-4" strip is set back in plane, there is a jump in the wall.
Having a control joint at all green lines would be important in my view as the outer walls will expand/contract and rotate the jog portion of the wall, causing cracks.

 

[jerseyshore]

Rarely do we solid grout walls here because no one wants to pay for that. It's most common during repairs really. I'm lucky if they grout the cells with the bars in it.

In the OP I think the CMU is continuous and flat, but the brick stops and starts at the green lines, where the CMU also extends higher up.

I feel like if that's the case and you don't put joints at both green lines, would anyone be surprised to see stress cracks at those corners in a couple of years?

 

[Ben29]

jerseyshore is right. The 8" cmu block is flat and continuous (no jogs in plan view).