Just how corrosive is this stuff in practice?
In particular, I am building with .15 retention CAC-C (UC4A)
Will this really eat nails, screws and Simpson clips? Does anyone have practical experience?
I have “ACQ” rated nails for my framing nailer but I am not sure they are going to be good enough. Do I need to try to find stainless framing nails? I guess I could use 3 1/2 SS deck screws.
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Replies
SS deck screws really suck, they're so soft. (And the treated is hard.)
McFeely's will probably have a good selection of SS framing nails.
Greg,
I don't take any chances. Just up on Alico is Gulf Coast Nail and Staple. I paid $306.00 for a box of 5,000 16# SS ring shanks just yesterday.
OK check back with me in a year. I am going to try an experiment. I will put together a sample of a few scraps of CaC with HDG nails, bright commons and a couple simpson clips and throw it out behind the shed. I will nail on some aluminum flashing and a piece of "patio" to simulate what you might do.
Give it a year in the weather and see what happens.
I will go with the SS nails on my project but I hope I can find them by the pound. I will never use a box.
Are you looking but bulk or gun nails? Don't know if Gulf Coast has bulk but if not KC Suppy does, $9.00 a pound maybe.
I'll be interested in your experiment. Most of my work is at the beach or on Sanibel and I've pulled down plenty of decks where the nails are gone except the heads. I'll use hot sipped on interior walls inland and at the beach but never outside.
I have a delivery coming from Shoreline Lumber tomorrow. If I can cattch them befoe they get out the door I will see if they have the SS nails. I need a bunch of SS screws for some Ipe decking they are bringing anyway.
I built a my deck last year and used this part number 1034-FT6 from McFeely's, they are 316 SS harder than the big box stores carry. Not cheap but worth the extra cost.
This will be a nominally dry location, inside an exterior wall.
SS fasteners
Disclosure: I'm just a DIY home owner, but I hope I'm a fairly quick study when it comes to stuff like this. YMMV
Yes, SS screws are different (it also depends on the SS formula, but usually not softer, but more brittle), so the number used may have to be increased. But for outdoor applications I'll still use them over the alternative (with the potential exception of DeckMate full lifetime guaranteed screws--however, I doubt the long-term verdict is in, yet). After tearing down and rebuilding two outdoor stairways [mostly PT] three years ago, I am a believer in SS for use with PT wood.
I've attached some photos of fasteners I removed from the two stairways (both were built in 1994-5) using whatever PT formula was available back then, probably the old arsenic formula CCA (outlawed for use in USA in 2004). Obviously, the broken, untreated lag screws were a mistake (not mine, but the carpenter's), but even galvanized nails were heavily degraded over the fifteen-year period. The only fasteners that were left in remotely their original condition were the SS.
SFAIK, the newer ACQ formula is mainly used for PT here in Japan now, but it's supposed to be at least as harsh on fasteners as the earlier stuff. For my money, I'll stick with SS until more certain research becomes available.
The science far project has started. I have a couple scraps of the new CaC .15 lumber with an assortment of fasteners and materials in/on it. Check back in a few years and let's see what happens.
Of course by then CaC lumber will be outlawed.
FWIW, I recently removed several of the old gold-colored deck screws (don't remember the name) from some old (probably CCA) treated lumber -- probably about 30 years old. The adjacent redwood lumber had rotted away (this is at ground level) but the screws were fine.
CCA is not an issue. The problem seems to be with the replacements.
Have you tried any of the borate treated stuff? Works fine for interior plates.
Lumber test
OK this is the PT lumber test
I am going to give it a year out behind my shed in the weather and see how things are going.
View Image
Don't apply for A JOB AS A FOOT MODEL, lol
My uderstanding of this is that the corrosion happens as a galvanic reaction and needs the presence of moisture - water to happen. I have seen and heard of rapid deterioration with fasteners in decks where water washes those connectors in contact with the copper wood.
But when the PT is already moderately dried when used for framing and the house is dried in appropriately and soon, there seems to be very little corrosin trouble
Yeah, to really make that test good the test piece needs to be buried somewhere. Or at least left laying on the ground.
PT Info
Greg,
Here is a good article on ACQ treated lumber and related fasteners.
http://www.nadra.org/industry_news/acqarticle.html
.
Yes, the chemicals do corrode the fasteners and hardware, at a surprisingly fast rate. There are fasteners available that are ACQ compatible, although testing procedures and results can vary quite alot between manufacturers.
http://www.screwsolutions.com/Bronze-Star-ACQ-Compatible_c_14.html