Maximum CMU wall height

[edwards1800]

New to engineering - New to the forum, thanks.

I am designing a basic 20' x 30' pumphouse for a small community. I have a basic CMU design with 10' ceilings, but I want 14' ceilings (due to some large tanks inside the bulding). The question is, can I take my default design that we've been using for years (with 8x8x16 block) and simply make it taller?

Like I said, I am totally new to this, and the best guidance I've found is from ACI journal in 1970 which says that h/t (is this the slenderness ratio) should be less than 20. That means I shouldn't go higher that 13'4", right?

 

[cvg]

reinforced grouted masonry can go to at least 25

 

[lsmfse]

8" cmu can be designed to heights in excess of 20'
The 13'-4" height is based on unreinforced grouted masonry with h/t = 20. For reinforced masonry, 16'-8" was the maximum height(UBC). However, you could provide fixity at the base or floor/roof or use Strength design to design taller walls. Be careful when you go taller since the wall ties into the diaphragm are critical(especially in seismic zone 4)

 

[JedClampett]

You need to hire a structural engineer to design a building. Stretching designs is negligent and possibly dangerous.

 

[cvg]

with 14' high walls, no stretching necessary

 

[edwards1800]

Thanks for the quick reply guys! I should have started my search for answers here.

 

[UcfSE]

edwards, are you an engineer?

You need to make sure you check the design of your walls. Do not construe the replies to mean you can simply add 4 feet of wall height without doing, checking or adding anything. Masonry can go to 14 feet, but not if it is not properly designed. Also, make sure you are using current codes as referenced by the governing building code in your area, not something from 1970.

If you are not an engineer or are not qualified to perform engineering, hire a licensed structural engineer to do so.

 

[jike]

A couple options come to mind:

Use engineered reinforced masonry

Pour the foundation wall up a couple of feet above the floor to decrease your masonry height to the allowable.

Brace the wall at the allowable height with bracing from the roof level.

I are required to follow the current governing code for masonry. An article from the 70's may likely be out of date, may mislead you and won't hold much creditability with a plan examiner.

Perhaps a short consultation with a local structural engineer would be beneficial.

 

[edwards1800]

No, I just play an engineer on TV.

Kidding aside, I was looking for tips fo where to go (options), and got a few, Thanks

 

[JAE]

Well, as long as you slept at a Holiday Inn Express last night, I'm OK with you designing anything!