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Nathan Woods, CCCA
Senior Member
Username: nwoods

Post Number: 19
Registered: 08-2005
Posted on Wednesday, September 21, 2005 - 08:19 pm:   Edit PostDelete PostPrint Post

Iím just starting to dig into the scary world of corrosion and pressure treated and/or fire treated wood products. Although Iím not clear on why, it seems that most mfrís of the chemicals used to create pressure treated and fire treated wood have changed their formulaís. As a result, the proper specification of which corrosion resistant fasteners to use has become much more complicated, or so it would seem?

After preliminary research (what did we ever do without Google?), it appears that each pressure treated wood vendor or product has itís own base chemical composition, and a specific fastener material must be used accordingly.

How is this managed at the Specification level?

How is this managed in the field?

If I have a pressure treated 3x mud sill at a fire treated shear wall panel, is the contractor expected to switch nail guns or cartridges when they do their nailing? This sounds rife for problems, failures, and potentially lawsuits.

I donít have any answers at this point. Iím quite sure I have not even thought of all the relevant questions I need to answer. For example, as Iím typing this, it occurs to me that stucco lath, flashing nails, railing bolts, etcÖall anchor to treated lumber, particularly on a Type III wood framed building.

Iím very curious to hear your collective thoughts on this, and hopefully, some proposed solutions!

Regards,

Nathan Woods
Southern California
Jerome J. Lazar, RA, CCS, CSI, SCIP
Senior Member
Username: lazarcitec

Post Number: 157
Registered: 05-2003
Posted on Thursday, September 22, 2005 - 12:22 am:   Edit PostDelete PostPrint Post

Nathan - Blame the EPA, suggest you catch up on your reading - Strongtie has some good info:
http://www.strongtie.com/productuse/PTWoodFAQs.html
http://www.strongtie.com/ftp/bulletins/T-PTWOOD05.pdf
Bottomline, we no longer specify standard galv fasteners in contact with PT wood, we prefer Stainless steel, if forced to specify galv. we go for the G185 hot-dipped galv. We also no longer specify aluminum flashing in contact with PT Wood, again we specify stainless steel or Kynar painted aluminum.
Mitch Miller,AIA ,CSI,CCS
Senior Member
Username: m2architek

Post Number: 58
Registered: 02-2004
Posted on Thursday, September 22, 2005 - 08:47 am:   Edit PostDelete PostPrint Post

there was another string here awhile ago when the issue arose. The real scary fact is that the treatments are high in copper content, so the galvanic action with other metals is the issue at stake. I have a power point presentation I did for my chapter and our offices. email me if you wish to see it.
Wayne Yancey
Senior Member
Username: wyancey

Post Number: 69
Registered: 05-2005
Posted on Thursday, September 22, 2005 - 11:42 am:   Edit PostDelete PostPrint Post

Nathan,

Nails:
For Borate pressure-preservative treated rough carpentry (dimension lumber and panel products, I specify Type 304 or 316 stainless steel or double hot-dipped STORMGUARD fasteners from Maze Nails.
For ACQ or similar pressure-preservative treated rough carpentry: Type 304 or 316 stainless steel.

Maze nails are available collated. Contractors like this feature. www.mazenails.com

Bolts, flat washers, hex nuts: Same rules as for nails in Borate or ACQ treated product.

W.R.Grace has suggested details for separating treated lumber from fasteners that is worth reading.

I spec Borate for wood above grade and not directly exposed to weather (such as furring and strapping for rainscreen cladding).

I spec ACQ for wood exposed directly to weather.

I hope this helps.

FYI, my region is the Pacific northwest (Marine climate).

Wayne
Steven T. Lawrey, AIA, CSI, CCS, CCCA
Senior Member
Username: lawrey

Post Number: 33
Registered: 08-2004
Posted on Friday, September 23, 2005 - 09:56 pm:   Edit PostDelete PostPrint Post

To get around fastener coordination I've started specifying untreated Doug Fir with galvanized fasteners for roof blocking. Got this tip from a talk given by Sal Verrastero at one of our chapter meetings. I'm in Philadelphia which has "whimpy" mid-atlantic climate. Thus far I haven't had to deal with wood building super structure, decks, pergolas, etc.

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