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RE: Brick veneer on PreEngineered Metal Building

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Roger, Paul and Will, thanks for your reply.

The background that I haven't disclosed yet is that the Owner wants to
purchase the building on Monday so I have to come up with the design
criteria for the building.  I raise the concern because I don't want to
show a foundation to accommodate a brick veneer if it is not practical
to add one in the future.  If they do want to add one then I believe the
wall construction has to be built now to accommodate the veneer.

My thought is to put metal studs behind the wall panel with a girt at
about the 14 ft. elevation.  The girt would be a rolled steel member,
not a cold formed Z shape. I probably will need to size the girt if
deflection is a concern.

I was considering recommending a lateral sway value of H/360 using a 10
year wind.  The studs would be designed for h/600 for its span and the
girt would be designed for L/500 to L/600 for its span, all using a 10
year wind.

Does that sound reasonable for a veneer, or too big?  AISC's Design
Guide 3 has a girt deflection of L/240<1.5 inches a 1/16" crack width at
base for side sway drift.  That translates to H/192.  All use 10 year
wind.

All this adds considerable cost to a PEMB.

Rich Lewis
Lewis Engineering
 
 

-----Original Message-----
From: Paul Ransom [mailto:ad026(--nospam--at)hwcn.org] 
Sent: Wednesday, January 19, 2005 8:23 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Brick veneer on PreEngineered Metal Building

> From: "Rich Lewis" <sea(--nospam--at)lewisengineering.com>

> I have had a request to design a foundation for a PEMB that will have
> metal siding now, with the potential for a brick veneer in the future.

> When I asked how the brick was going to be supported I was told they
> screw wall ties into the metal panel and build the walls.  The eave
> height of the building is 28 feet.
>  
> My apprehension is the metal panel wall system is not stiff enough to
> support the masonry veneer.  A wall panel supported by girts at 7 ft.
on

> I was told this is common practice.  Now I know just because it is
> common practice doesn't mean it is right.  I would like to know what
> common design recommendations should be made to the steel design and
> wall system to provide an adequate stiff backup in the future.

My first thought is, "why worry about it if you are not responsible for
it." However, I wonder if the PEMB manufacturer has been made aware of
the plan for a future brick veneer (added seismic load, if nothing
else). Frequently, the builder/owner will omit full disclosure to the
PEMB manufacturer to get a lower price. Secondly, the builder (who has
done this a million times before and is always the low bid ...) may not
have advised the owner of the issues. He may believe what he is doing
but he will blame the engineers when something goes wrong.

Typical spans 20' - 25', with 8" cold-formed C or Z spaced at 7' is not
likely to give the stiffness that you believe to be required. Add the
flexibility of the panel, even at the stiffer ribs, and anything could
happen.

Typical PEMB girt: L/60 to L/120
Typical PEMB panel: L/60 to L/120
Cumulative.  

-- 
R. Paul Ransom, P. Eng.
Civil/Structural/Project/International
Burlington, Ontario, Canada
<mailto:ado26(--nospam--at)hwcn.org> <http://www.hwcn.org/~ad026/civil.html>

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