| Author |
Message |
Anne Whitacre, CCS CSI
Senior Member
Username: awhitacre
Post Number: 284
Registered: 07-2002
| | Posted on Wednesday, January 11, 2006 - 06:15 pm: |    |
story: we have a curtainwall with stone panels, glazing units, and concrete panels, and aluminum framing. there are embeds in the panels and also in the building floor for attachment. We specified all embeds as galvanized and this was agreed to by the Owner's curtainwall consultant. it was bid that way by the subcontractor and they have agreed to provide galvanized for all embeds. Building is in Seattle, not directly on the salt water (but can see it); about 20 stories tall.
However: the sub is saying that galvanizing isn't necessary and that they think this "industry standard" is overkill, provides schedule and cost problems. (keep in mind they are providing galvanized but since we work with them a lot, want us to change it for future work)
question: what is your practice regarding galvanizing embeds, what part of the country are you from? I'm trying to see if there is any general agreement in the industry... or not.
thanks... |
Jim Brittell
Senior Member
Username: jwbrittell
Post Number: 12
Registered: 08-2004
| | Posted on Wednesday, January 11, 2006 - 07:21 pm: | |
Anne,
Here at UC Irvine we require all exposed steel to be galvanized or protected with a high-performance coating system. Since embeds aren't usually painted, we insist on galvanizing. Our campus is about 3 miles from the ocean. Since the requirement is included in our campus standards & design criteria, we don't get arguements about it being overkill. |
Ronald J. Ray, RA, CCS, CCCA
Senior Member
Username: rjray
Post Number: 52
Registered: 04-2004
| | Posted on Wednesday, January 11, 2006 - 07:37 pm: | |
I don’t see galvanizing of steel embeds as overkill. In fact, I have specified stainless steel embeds for projects in Boston, Massachusetts and in Tampa, Florida. True, welding of stainless steel requires more skill, but the building types have justified this level of quality, and associated cost. The one Seattle project I was involved with, I specified galvanized steel embeds.
As you know, the weak element of galvanized steel embeds are the field welds, which seldom receive the proper surface preparation to receive the cold-galvanized “touch up” paint. Perhaps the subcontractor’s rational is, that since rusting is going to occur at the field welds regardless of the shop finish on the embeds, why spend the money on galvanizing something when it is just going to be burned off in the field? This argument may have merit, considering that unless there is water infiltration into the area of the embeds, surface rust on an embed contributes little if any degradation to the steel. However, it is not an argument I would accept, as I see the galvanizing as cheap insurance. Some years back, the 1960 something SOM award winning BMA Tower in Kansas City, Missouri experienced the marble panels falling from the facades due to rusting of the non-galvanized steel embeds, or so the courts determined. |
Sheldon Wolfe
Senior Member
Username: sheldon_wolfe
Post Number: 185
Registered: 01-2003
| | Posted on Wednesday, January 11, 2006 - 10:52 pm: | |
We specify stainless for anything that is in contact with stone, and we're over 1,000 miles from the ocean. (Lake Superior is just over 100 miles, but that's fresh water.) Maybe it's overkill, but I don't like the idea of either stains or falling veneer. |
Ronald J. Ray, RA, CCS, CCCA
Senior Member
Username: rjray
Post Number: 53
Registered: 04-2004
| | Posted on Wednesday, January 11, 2006 - 11:00 pm: | |
I agree with Mr. Wolfe. Any metal anchors or supports in contact with stone or cast stone, I specify to be stainless steel, regardless of the environmental conditions. |
William C. Pegues, FCSI, CCS
Senior Member
Username: wpegues
Post Number: 517
Registered: 10-2002
| | Posted on Thursday, January 12, 2006 - 01:33 am: | |
Anne,
Since the 70s, and with more than 1 architectural firm over that time, the standard practice that I both encountered as well as recommended was that anything embedded or anchoring stone was stainless steel. That was the standard practice at SOM when I was with them in the 70s through early 80s - regardless of the location of the project. It was in their master and had been for quite some time. Likely not from the experience Ron relates since their office standard predates the date of failure of his example...though not every office followed the Chicago office's recommendations.
WDG had been following the same practice before I joined them, here in DC, and we continue that throughout this region inclulding projects well into the mountains to the west, and in our projects out of our Dallas office and that general region.
I can't recall any significant issue even being rasied to "VE" this to galvanized in the past couple years. Every few years or so, some one job where an unknown sub has gotten assigned the work by the contractor has raised the question. We say no, the issue goes away.
Here in DC, there have been a couple buildings where the stone was replaced or where significant repair was required after a number of years where stainless was not used. I don't know that they were using galvanize or just primed steel. One of these actually had falling stone, and Dave Metzger may remember it - the building at the south east corner of Farragut Square on Eye and the extension of Connecticut Avenue, its a white panelized marble building. For years they put up with severly damaged panels until some fragments fell and they did repair to it. Not pretty to look at today either.
I can see a point of 'why galvanize' since it gets lost in welding and is frequently difficult, or at least poorly, repaired. But I think the real point to don't galvanize is not to go to paint coatings at all, use stainless steel.
William |
George A. Everding, AIA, CSI, CCS, CCCA
Senior Member
Username: geverding
Post Number: 97
Registered: 11-2004
| | Posted on Thursday, January 12, 2006 - 10:52 am: | |
Another vote for stainless steel here (St. Louis) for stone embeds, but this thread made me go back to the Indiana Limestone (ILI) spec, where surprisingly, they allow galvanized as well. I am so used to using only SS that I was sure ILI required it.
Precast Conscrete (PCI) - at least in “Parking Structures: Recommended Practice for Design and Construction” which is all I have immediately available- says:
“Depending on the degree of exposure, plates should be coated with rust inhibitive paint, epoxy painted, galvanized, or made from stainless steel to prevent long-term deterioration. The protection should be mandatory where plates cannot be reached in the future for protective maintenance. Where welding of galvanized occurs, the weld slag should be removed and the weld coated with a liquid galvanizing coating after the steel has been scoured with a stiff wire brush.
“Some designers have specified the use of stainless-steel connections to prevent long-term corrosion. While this may appear to be the ultimate in corrosion protection, users are cautioned that welding produces heat that can create adverse hardware expansion adjacent to the assembly being welded. This can cause cracking in the adjacent concrete and promote accelerated long-term deterioration. This can be resolved by keeping the edges free from adjacent concrete to allow expansion during welding without spalling the concrete.”
This is in agreement with much of what has already been suggested. If you are looking for "industry standards" to back up your position, I am sure you will find similar language in the PCI online document related to your specific application. |
Don Harris CSI, CCS, CCCA, AIA
Senior Member
Username: don_harris
Post Number: 51
Registered: 03-2003
| | Posted on Thursday, January 12, 2006 - 11:19 am: | |
Anne:
Stainless for stone veneers.
Galvanized for pre-cast.
Sometimes we get a contractor that wants to VE the galvanized. As I recollect, it was only accepted once, by the Owner, over our objections. We don't discuss substitutions for stainless in stone assemblies. |
Tracy Van Niel
Senior Member
Username: tracy_van_niel
Post Number: 153
Registered: 04-2002
| | Posted on Thursday, January 12, 2006 - 01:23 pm: | |
Anne:
The way I read your original post is that the subcontractor only wants to provide "regular" non-coated or non-galvanized steel instead of the specified hot-dip galvanized.
We ran into that on a student housing project and the issue was that the contractor did not order the hot-dip galvanized steel in time for it to arrive on site at the proper time in the construction schedule. They wanted to substitute non-galvanized steel that had a painted finish. We told them that they could either provide the hot-dip galvanized materials as originally specified or stainless steel, but that painted steel was not acceptable. I believe we ended up with hot-dip galvanized materials as originally specified. |
Anne Whitacre, CCS CSI
Senior Member
Username: awhitacre
Post Number: 285
Registered: 07-2002
| | Posted on Thursday, January 12, 2006 - 05:16 pm: | |
actually, I mispoke a little bit, but this information has done what I wanted to do anyway. we specified galvanized; the sub is providing galvanized, but the General wants to decrease costs so its the General who is questioning "what is industry standard"? The sub came back to us asking for help to keep the galvanized. This series of replies from you all has helped provide us with another argument to the General. (it is a little more complicated than that vis a vis the relationship between General and Owner, but the upshot is that it is the General pushing for the cost/quality reduction, not the sub.) I prefer galvanized or stainless and this has helped me push the point; especially the recommendation from PCI.
Thanks |
John Bunzick, CCS, CCCA
Senior Member
Username: bunzick
Post Number: 453
Registered: 03-2002
| | Posted on Friday, January 13, 2006 - 09:08 am: | |
If the substitution had gone ahead, would the general contractor have given all of the savings back to the owner? (This is a rhetorical question.) |
Richard L Matteo, AIA, CSI, CCS
Senior Member
Username: rlmat
Post Number: 137
Registered: 10-2003
| | Posted on Friday, January 13, 2006 - 10:55 am: | |
I verified it with my former firm on the East coast. We did work all over the US that included a number of mid-rise to high-rise buildings.
Basically, the embeds in concrete or masonry were usually galvanized and the stone anchors were always stainless steel.
We never got an argument from the contractors that I'm aware of. If we did, we probably told them it wasn't acceptable otherwise. |
Susan McClendon
Senior Member
Username: susan_mcclendon
Post Number: 36
Registered: 01-2005
| | Posted on Friday, January 13, 2006 - 11:51 am: | |
The garage I park in is precast with exposed embeds. They were not galvanized and the whole thing leaks like a sieve so they are rusty and in some places the concrete has spalled -- pretty scary (I prefer to park on the top deck; fortunately it's only 2 levels). Think about what could happen with concealed embeds, just like concealed metal studs rusting. You can justifiably tell this dope of a GC that the "industry" you asked votes for protection. What "industry" did he think might allow this? |
Wayne Yancey
Senior Member
Username: wyancey
Post Number: 93
Registered: 05-2005
| | Posted on Friday, January 13, 2006 - 04:47 pm: | |
Anne,
If your embeds for all exterior cladding assemblies are located interior of the air/vapor barrier and exterior thermal insulation (i.e. at ambient interior temperature) then embeds without hot dip galvanizing for the embeded portion may be OK but the nonembeded portions should be hot dipped galvanized or protected by some other zinc rich coating such as offered by Tnemec. Aluminum curtain wall anchors are typically located interior of the air/vapor barrier and insulation at the vertical mullions; will be at room temperature by default; and well above the dew point temperature to mitigate the occurence of condensation. Opaque spanderl panels can be glass, metal, stone, etc.
Your original post is not clear if the concrete panels noted are precast or captured in the curtain wall.
Our latest Walters and Wolfe glazed aluminum curtain wall shop drawings show steel embeds and aluminum angle brackets. No mention of stainless steel or hot dipped galvanizing for the embedded portions for those items located interior of the air/vapor barrier and spandrel panel insulation.
Wayne |
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