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T.J. Simons, CSI, CCS
Senior Member
Username: tsimons

Post Number: 15
Registered: 08-2005
Posted on Friday, January 22, 2010 - 11:26 am:   Edit PostDelete PostPrint Post

Specifications for a hospital project we currently have under construction require a number of exterior wall mockups, tested to AAMA 501.2-03. The building is a 4-story steel framed structure with a cement plaster skin over metal stud framing and glass-mat faced gypsum sheathing. Windows are aluminum storefront framing, typically in a punched opening.

Owner has now directed us to specify a “negative pressure” test on the wall mockups as well. This owner completed a project several years ago in the same region, using a test methodology based on ASTM E 331, and AAMA 502.02, Method B. We were given a copy of the architect’s specification for mock-up testing, and directed to modify our specifications accordingly.

I pointed out that ASTM E 331 is not appropriate for this type of wall assembly, and I didn’t believe it would address the primary concern, which is water intrusion at the perimeter joints of the windows. I further advised the owner that I believed it highly questionable we could enforce this test as a Contract requirement, using ASTM E 331 test methodology on this type of assembly.

Are there any other AAMA or other test methods which specifically address field testing of this type of wall assembly?

I don’t want to specify something we can’t enforce, and devising a test methodology from scratch for something like this is outside our expertise as architects.
Ron Beard CCS
Senior Member
Username: rm_beard_ccs

Post Number: 327
Registered: 10-2002


Posted on Friday, January 22, 2010 - 01:29 pm:   Edit PostDelete PostPrint Post

T.J. I assume that the stucco is over a wire mesh. Does your design call for a drainage plane behind the stucco?
"Fast is good, but accurate is better."
.............Wyatt Earp
(Unregistered Guest)
Unregistered guest
Posted on Friday, January 22, 2010 - 12:22 pm:   Edit PostDelete PostPrint Post

I share your concerns and have expressed similar reservations in requiring this sort of testing at system "interfaces." It's ludicrous. I know of no test for this condition. I completely agree with you that this is something architects should steer well clear of. Here's the deal - how is a determination made, at the interfaces of cladding assemblies, what constitutes a failure? If that can be estalished, who's fault is it if something fails? The Contractor will CERTAINLY argue that the interface was built exactly as shown on on the drawings. The the architect looks like a boob and has no defense.

Static, negative pressure field testing is overkill and proves very little. it is not a real world test. AAMA does have a test (or one in the making) for dynamic pressure testing that requires a big old fan to be hoisted into position a few feet from the building exterior, spray rack spewing water. This is the only type of test that should be considered for exterior cladding systems not addressed by tests developed for glazed framing systems.

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