Fasteners in coastal environments

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Author Message John Bunzick, CCS, CCCA Senior Member Username: bunzick Post Number: 270 Registered: 03-2002 Posted on Wednesday, September 29, 2004 - 12:04 pm:    Condition: Fasteners for windows in residential work in coastal communities. Also, fasteners for trim and miscellaneous items. Question: Would you specify only stainless steel? How about hot-dip galvanized (when it would not create galvanic corrosion issues)? What about fastener with non-metallic anti-corrosion coatings? Anne Whitacre, CCS CSI Senior Member Username: awhitacre Post Number: 127 Registered: 07-2002 Posted on Wednesday, September 29, 2004 - 12:26 pm:    John- on the west coast, especially where subject to salt spray, we have not had good luck with either galvanized fasteners. I typically go with stainless steel or some marine bronze. I have seen some commercial coatings (Tnemec and the like) but usually those only work for the thing being fastened to, not for the fastener itself. Even the heavy galvanized (G-90) doesn't work as well here as stainless, but I do use that coating for doors and frames on the northwest coast. (Unregistered Guest) Unregistered guest Posted on Wednesday, September 29, 2004 - 12:36 pm:    You may want to be a bit more definative about what you are classifying as a coastal community. There is a Tech Note #140 published by the Light Gauge Steel Engineers Assocition that addresses some of the corrosion issues in coastal areas - albeit on steel framing. There is also a sizable amount of info on info@galvinfo.com website. In our coastal environmental work we typically uses only stainless steel for - to quote a smart person that I know "Weight the cost of going to stainless steel in comparison to the amount your attorney will charge you to defend you when the project fails" John Bunzick, CCS, CCCA Senior Member Username: bunzick Post Number: 271 Registered: 03-2002 Posted on Wednesday, September 29, 2004 - 12:49 pm:    A coastal community for our purposes is: City or town bordering a salt-water coastline, with some structures fronting the coastline and some away from the water up to roughly three miles. Anonymous   Posted on Wednesday, September 29, 2004 - 07:24 pm:    Check the building code and see what it says for the area in question. In many coastal areas, window units are required to comply with specific code requirements for high velocity hurricane zones. To get the necessary approvals (either a Miami-Dade NOA or compliance with ASTM E 1996 under the IBC), the units are tested as an assembly and that includes the hardware. The NOA will list the hardware tested with the unit. Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 48 Registered: 05-2003 Posted on Thursday, September 30, 2004 - 12:53 am:    We typically spec Type 304 or 316 stainless steel, which has the best resistance to corrosion from salt spray as tested by ASTM B117. WE do not recommend Type 410 stainless fasteners as these are magnetic and not reliable. I believe stainless wwill endure 1800 hours of salt spray prior to red rust appearing compared to ITW Buildex White Ultrashield coated fastenrs which can endure 1500 hours. We find that the contractor will try and substitute 410 for 304, we seldom let them. No 316 is the best stainless steel for corrosion resistance and we specify this when we write spec for severe weather locations. For example for a number of projects in Vero Beach we specified No. 316 fasteners and straps for wood roof trusses, we have not heard of any of those roofs failing from the recent hurricane. We agree that you need to check the product approval for the window, some manufacturers do not test with stainless steel and if they are accepted by the Owner you may find yourself biting the bullet and agreeing to a coated steel product, like the ultrashield coatings from ITW Buildex. Suggest going to the Stainless Steel Information Center website: www.ssina.com for explanations. Also www.ianosbackfill.com/building_science has a good explanation of fastener galvanic reactions pertaining to coastal construction. David Axt, AIA, CCS, CSI Senior Member Username: david_axt Post Number: 358 Registered: 03-2002 Posted on Thursday, September 30, 2004 - 01:27 pm:    Speaking of fasteners and to diver the subject a little bit. I see fasteners with a "yellow gold" looking plating on them. What is this plating material? Richard L Matteo Senior Member Username: rlmat Post Number: 67 Registered: 10-2003 Posted on Monday, October 04, 2004 - 12:49 pm:    To answer David's question - it is commonly called "cadmium plated" It is not a finish I would recommend for coastal environments. Anonymous   Posted on Thursday, October 07, 2004 - 01:05 pm:    The question of what constitutes a marine community probably hinges on its exposure to corrosive salts. Near the ocean, communities can experience either fog or wind blown moisture, which can cover salt laden moisture inland. How far this moisture can go is probably affected by the type of weather and the geology. My experience in California is that when it is foggy within four miles of the ocean there is enough salt in the moisture in air to cause the electrical connections on the electric utility poles to crackle. It seems likely that the same salty moisture would also affect metals, such as fasteners, metal roofing and siding, and aluminum window framing. Different areas will experience different exposures. Some areas have extensive estuaries and salt marshland. The eastern seaboard, especially Florida, will experience much greater windy weather coming off the ocean than other areas. For these conditions, I have always increased the level of corrosion resistance. For exposed metal fasteners this means using stainless steel. The trouble with galvanizing is not on the exposed surface, but in the joint between the fastener and the substrate where the bite can scrape off the coating. Is stainless steel worth the expense for ordinary handrails and bike racks? Maybe not. But these issues could be addressed with all shop welded construction using as few fasteners as possible. John Bunzick, CCS, CCCA Senior Member Username: bunzick Post Number: 273 Registered: 03-2002 Posted on Friday, October 08, 2004 - 08:37 am:    Thanks for all of the input. Fog is definitely a consideration in the two California communities where we're doing projects. Y'all convinced me to go with my leaning to stainless steel. Richard L Matteo Senior Member Username: rlmat Post Number: 69 Registered: 10-2003 Posted on Sunday, October 10, 2004 - 02:42 pm:    John, Growing up on the East Coast, where fog, moisture, and salt air are a major consideration, I agree with your decision to go with stainless fasteners. One additional note - Type 316 stainless is more corrosion-resistant than Type 304.