| Author |
Message |
Wayne Yancey
Senior Member
Username: wyancey
Post Number: 39
Registered: 05-2005
| | Posted on Tuesday, August 02, 2005 - 08:04 pm: |    |
Thanks for all of your help last week in providing information regarding failures of thin brick facing over architectural precast.
An associate spoke directly with Sid Freedman, Director Precast Concrete Services at PCI. Sid provided some information I thought I would pass along for your use:
PCI will be publishing a document in the near future that outlines the requirements for thin brick. Sid provided a draft copy of the document which is essentialy in final form (available on request). While not explicit, PCI will be recommending the use of thin bricks for facing materials on architectural precast over the use of soaps or half-bricks. To date they have received endorsment of these specs from major suppliers including: Endicott, Feldhaus, Summitville and Metro.
PCI has funded a study of vapor barriers used in conjunction with APC--report should be available in 2 weeks. The study is being conducted by Martha Vangeem at Construction Technology Laboratories in Chicago and evaluates the 4 different wall assemblies utilizing precast. The goal of testing is to evaluate optimum vapor barrier location in different climates. Will be interesting to see these results.
Half-bricks have greater abosorption and this has potential to further reduce bonding through crypto effloressence. This is in part the reason PCI is recommending the use of thin bricks.
Further the use of sealers is discouraged in these applications.
Use of half-bricks (soaps) generally requires the use of a self consolidating concrete--thin brick applications do not require this.
Sid feels that the use of a sandwich panel should be further explored for our project. The surface applied insulation in our project will be not be much more economical in his opinion.
According to Sid, the use of half-bricks is limited to Michigan--the rest of the world is moving to thin brick facing of precast due superior performance and economy. Seems to be some disagreement about this point in several of the circles my associate has been talking to. My associated is of the opinion it is clearly driven by financial interests as he has yet to hear of any catestrophic failures of thin brick facing assemblies.
Sid recommends the use of ASTM C1088 Type TBX thin brick over TBS which has lower tolerances. The same holds true for full size bricks under ASTM C216 - Type FBX over FBS.
He pointed us in the direction of Scott Systems (http://www.scottsystem.com/index.htm) who have proprietary brick inlay systems and test data showing results for freeze/thaw and bond strength. We are not sure how to interpret these results as the concrete mix and brick characteristics can play a significant role in the outcome. Also, we always question voluntary testing conducted by manufacturers. We will have to look into this further before we put all our eggs in this basket.
The document from Scott Systems is available for your review upon request.
I hope you find some of this information valuable.
My e-mail is wyancey@morrisonhershfield.com
Wayne |
Doug Brinley AIA CSI CDT CCS
Senior Member
Username: dbrinley
Post Number: 52
Registered: 12-2002
| | Posted on Tuesday, August 02, 2005 - 08:34 pm: | |
Wayne,
THANK YOU for very good information. (I feel SO 'old school' sometimes).
I learned from experienced old 'scalawags' who didn't have access to job-specific envelope mockups (except for curtainwall); and we didn't have self-consolidating concrete (unless punching it down with a length of rebar could be considered self-consolidating). |
William C. Pegues, FCSI, CCS
Senior Member
Username: wpegues
Post Number: 438
Registered: 10-2002
| | Posted on Wednesday, August 03, 2005 - 10:02 am: | |
Grerat follow up, thanks. One of the things about this evolving technology is that there are some things we don't want to form a definite opinion on, and when writing a master version of a spec for something like this, fill it up with notes about checking on the lastest status from various sources.
Because it involves the use of brick, I know that BIA also has some input to what is going on with this type system - from the brick's point of view. The true lead though is the precast groups.
Oh - one thing I forgot to mention, you can actually get some degree of 'tooling' profile to the joint, it does not have to have that totally flat look to it. But, it comes with a price, just like the smaller joints. It will never look like a nice concave tooled joint, but its better than the totally flat look.
William |
John Bunzick, CCS, CCCA
Senior Member
Username: bunzick
Post Number: 390
Registered: 03-2002
| | Posted on Wednesday, August 03, 2005 - 12:28 pm: | |
For the joints, one could consider using the pricier tooled-look in visible locations (first two floors?) and the less expensive elsewhere. When I looked at SFMOMA, I would never have realized it was brick-faced precast if not for the ground level panels. They had the flat joint and the tell-tale appearance of cast concrete rather than tooled mortar. |
Anne Whitacre, CCS CSI
Senior Member
Username: awhitacre
Post Number: 229
Registered: 07-2002
| | Posted on Wednesday, August 03, 2005 - 01:42 pm: | |
we do brick faced precast occasionally (but not using thin brick) and we write very tight tolerances on the vertical and horizontal jointing that carries across panels. Even though the panels themselves often looked brick-like, there was a tell-tale discrepancy in the joint lines from panel to panel -- they just weren't lining up in a way that would make the panels disappear. At one medical campus we have done enough of those projects with the GC that they have derived some internal controls that help with making the exterior walls look seamless. And yes, the tooled-in joints make a huge difference in that appearance. |
William C. Pegues, FCSI, CCS
Senior Member
Username: wpegues
Post Number: 447
Registered: 10-2002
| | Posted on Friday, August 12, 2005 - 04:33 pm: | |
Anne,
Just this afternoon I received in the mail a promotional brochure from Shockey. On the cover is a 17 story building with what looks like a cornice pediment that goes up another 2-1/2 stories to the peak that is all thin brick clad precast concrete. It is described as...
"A new multi-use development in historic Canton - the place to be in Baltimore - features an office bilding with thin-brick clad architectural precast..."
"130,000 square feet of architectural precasat concrete clad with Endicott "Red Ironspot" thin brick"
They listed the architect as Whitney Bailey Cox & Magnini, LLC of Baltimore as both Architect and Engineer.
Shockey is one of the ones over in this region that has been doing thin brick clad precast for quite some time in significant quantity, large projects. Thought I would mention this since this is what one would call a "significant" use of the product.
William |
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