ACQ preservative and galvanized vs. stainless stell 2

[hippo11]

I was looking at the Simpson catalog on pg 11, and it recommends that all connectors be stainless steel, not galvanized, if the wood in contact with the connectors has a preservative content of ACQ/MCQ > 0.40 lb’ft3 …


So my question is, for a project on the beachfront, should we anticipate the wood having an ACQ content this high? How do I know what ACQ content the wood treater will use? And what is the $ difference between galvanized and SS finish?

 

[MightyPirate]

Here's a good site to look at:

http://www.nadra.org/industry_news/acqarticle.html

Also, check out the American Wood Protection Association page:

http://www.awpa.com/

My understanding is that most PT lumber should have hot dipped galv. (HDG) connectors at a min. but that significant corrosion will occur (probably not to failure but I wouldn't like it). Thus, the reason for stainless.

As for the content, I couldn't find anything with a brief google search but I would contact your local lumber supplier, see if they have that. Also, they might use a different preservative such a Micronized Copper Quaternary (MCQ) or specify that they use ACQ with no ammonia (both result in a med. corrosive level which according to simpson require only HDG).

 

[MightyPirate]

Oh, and contact your local simpson supplier for quotes on the cost difference. If it's only a few connectors then it wont be much, otherwise it could get expensive.

 

[SlideRuleEra]

Treated wood can, and should be specified by the Engineer, just like any other building material. For ACQ, typical levels of preservative retention are:

0.25 lb/ft^3 for above ground, non-structural use.

0.40 lb/ft^3 for either above ground structural members or ground contact for non-structural use.

0.60 lb/ft^3 for structural members with ground contact.

A tag should be attached (normally stapled) to each piece of lumber indicating the preservative type and retention.

You mention that the project is on the beachfront. If this is a saltwater beach, use of stainless steel fasteners would be wise, even if treated lumber were NOT being used.

The difference in cost between galvanized and stainless steel fasteners is significant, but be sure to take into account that the cost of ANY fasteners will most likely be secondary compared to the lumber cost.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[ctcray]

We deal regularly with USP products and use their Triple Zinc coated products for use with ACQ treated lumber. Most treated deck lumber is 0.40 lb/ft^3 ACQ. However, CCA treatment is still used for treated Glulams and marine grade lumber. Looking in the USP Retail Price Guide available on their website, an 18 gauge, 2x10 joist hanger in Triple Zinc is $1.46, in their Gold Coat (2x as resistant as Triple Zinc) is $2.95, and in Stainless Steel is $11.03. As someone already said, in a marine environment, you should probably go with stainless steel, HOWEVER, the problem you'll face is that only a small portion of the metal connectors available from USP and Simpson are available as stainless steel.