Max Brick Veneer Height? 1

[structurebeton]

Can someone give some advice on how to figure the maximum height of brick veneer withou providing intermediate lintel support? I am talking about more than 50ft of brick. Should it be supported at intermediate floors? (I am not talking about lateral support)

 

[blake989]

What type of backing? there are prescriptive requirements for height in ACI 530-05 chapter 6.

 

[structurebeton]

8" o 12" CMU backing

 

[jike]

If it is over 50 feet in height, I would recommend that you support the brick vertically at the floor line. In muli-story construction with low floor to floor heights sometimes you can get away with supporting the brick vertically at every other floor. You want to support the brick vertically at roughly every 18 feet to allow for its vertical growth. You need to detail the shelf angle properly with flashing, a metal drip, a compressible filler below the angle (to accomodate the growth) and notched brick if a small looking joint is desired by the Architect.

If I remember correctly, it will grow at approximately 1/10" per 10 foot of height.

 

[concretemasonry]

You cannot just stack up 50' of brick without any soft joints or relief angles.

Brick has an long term expansion. Steel, concrete and concrete masonry shrink or creep with time or loads.

It is not necessarily a structural problem, but a detailing/application situation.

The brick will go through its long term expansion a cause severe damage at windows or anything else that is rigid.

Take a look at the BIA (Brick Instutute of America) or similar for recommendations on the spacing of vertical joints/support.

Dick

 

[mbullism]

I think IBC 2003 defers to ACI 530, which limits you to 30' without relieving angles etc. (chapter 6?) Here in MA we are limited to 30' as well unless analyzed by a design professional...

 

[mbullism]

Oh yeah.. the 30' has to start at a non combustible foundation... I don't think you can start at the first upper floor and go that tall-

.02

 

[structurebeton]

Based on your answers, I would have to do a brick lintel, every 18' max, vertically to allow for vertical movement of adjacent structure. That means, attaching an angle directly to the backing CMU...the CMU itself will be 50 ft tall...Would that be a problem?

 

[jike]

We are not talking about a lintel. You need a continuously supported shelf (relief) angle with soft joints. 18 feet is not a magic number, but I would not exceed it. I would try to support the brick at each floor line, if possible.

If the CMU backup runs up continuous past the floors, then you will need to support off of the CMU. Don't foget to tie your backup to the structure and account for the eccentric load due to the brick.

If the CMU backup sits on the structure at each floor, then you need to support your brick off of the framing.

 

[structurebeton]

got it. Yes, I will provide relief angles at each floor level. Also, the CMU backup will be braced of the structure, so that should compensate for the eccentric loading from the brick.

Thanks

 

[jike]

I do not believe the CMU tie to the structure will eliminate the eccentric load on the CMU from the brick.

 

[structurebeton]

Not eliminate teh eccentric load, but a well placed angle support, the floor tied into the CMU will counteract somewhat the eccentric load generated from the brick...I probably will design as if not braced, but the floor tied into it will give me more confort level.

 

[jike]

Model say a 3 span continuous beam (CMU backup)in the vertical position like a wall. Provide a pinned support at base and roller supports at the other locations. Apply external moments at the two intermediate roller supports equal to the moment generated by the brick eccentricity and see what kind of internal moments are generated in the backup CMU. Combine these moments with the wind or seismic loading.

This is what I am trying to describe to you.

 

[structurebeton]

I will do that. Thanks for the advice.

 

[ddbrown]

I worked as a structural engineer in the masonry industry for many years and am technical consultant for the Utah Masonry Council. Brick veneer's weakness is that it is prone to cracking without adequate steel stud backup (l/600). The rule of thumb used is 30 ft maximum between shelf angles (whick I believe is controlled by the L/600 deflection criteria). Any more defelction than that and then the bed joints are prone to cracking and moisture penetration. If you need to go more than 30 feet without shelf angles (or vertical sppt), then I would recommend a structural brick (technical term by ACI 530 and IBC is "Hollow Clay Masonry"). These can be reinforced and will reduce lateral deflection.

A great publication that discusses this topic is at the Western States Clay Products Association website (

http://www.brick-wscpa.org)

The publication's name is "Design Guide for Anchored Brick Veneer".