Building a deck. Ordered supplies from McCoys, a regional lumber yard, not a home center. Delivery truck shows up and drops the load. Sorting through the stuff, I come across the box of bolts, and discover that they are bright zinc plated, not galvanized like I ordered. Took them back to the store and got into a discussion with my salesman. He says what’s the problem, this is what all the contractors use to build decks. I try to point out that galvanized costs twice as much (that’s why everybody uses brights) and lasts 4 times as long. Then I discover that they don’t even carry galvanized! He says don’t worry, nobody will notice, and besides, that’s what every contractor uses (apparently he likes that phrase). Somebody please tell me I’m doing the right thing to spend the extra few bucks for galvanized. After all, the lumber is wolmanized, shouldn’t the bolts be treated also?
Replies
There was an article in FHB some years ago about a long term study by the US Forest Service wood products lab, or some such outfit, about the performance of nails in wood decks. My recollection is that after 20 years, the galvanized nails were just about as rusted as the plain steel nails, and only the stainless steel nails had held up at all. I don't know if bolts would necessarily act the same way, since they start out much thicker than nails, but what I concluded from the article was, Stainless steel fasteners only in exterior applications.
Edited 6/23/2002 12:20:18 PM ET by Uncle Dunc
I tried searching at http://www.fpl.fs.fed.us/search_pubs.htm
And the only thing that I could find was pub discribing the different type of wood preservative treatments.
http://www.fpl.fs.fed.us/documnts/techline/III-1.pdf#xml=http://216.48.37.142/cgi-bin/texis/webinator/newsearch/xml.txt?query=galvanized+fasteners&db=fsr&id=3cfc6a967
Under water bases it said that all water based treatments are corrosive and that galvanized or SS fasteners should be used.
The article was in FHB #102, entitled "Details for a Lasting Deck." I didn't see any references in the article to government publications, but the article was written by employees of the Forest Products Lab.
I've got a couple of yards in my area that also DO NOT carry galvanized, so I usually go to a specialty house that deals in nuts, bolts, and screws exclusively, in a dizzying array of sizes, types, materials, and finishes.
That LY guy is full of crap. In my experience, the galv. always stays looking good longer (yes, it eventually starts showing rust). In the long term, I don't think galv. or plated make any difference- the deck will rot before they ever fail. Again, the galv. looks better longer, and I would rather have my clients happy with the appearance.
Ken Hill
Elcid,
Here is my take based on actual experience having personally removed bolts for inspection at varying intervals.
First, it is my experience that the chemicals in cca treated lumber are extremely corrosive to any fastener. I believe I was informed that copper chromium arsenate (or whatever) is a salt. So it makes sense.
Second, Zinc plated fastners are a bad choice and yes, probably 95% of contractors and homeowers use them in exterior applications. A key factor relating to the longevity in fasteres in exterior applications is how much plating is removed during the driving of the fastener. Drive a plated screw (zinc, galv, ceramic, whatever) into your material, back it out and see what's left. Zinc lag bolts are at an extreme disadvantage if you've ever backed one out. And that's been my experience. We have replaced rotten treated decks as few as seven years old and when we backed out the lags, the threads were corroded away. I recall backing out zinc, but I'm sure galv wouldn't fair a whole lot better. I have seen evidence of rust on stainless fasteners, but if properly sized and of the appropriate alloy, they will obviously outlast zinc or plated, but they are pricey, and most homeowners would generally not be interested in spec'ing a better fastener especially if it resulted in additional cost. The question they would ask is " do I really need hundreds of dollars in stainless steel fasteners, the other guy didn't even tell my what he was using?"
Third, we attach ledgers with galv. lags and carriage bolts wherever possible to prevent withdrawal of all the fasteners. This would be the primary cause of a catastrophic deck failure. Posts, rails and everything else is more of a maintenance issue from the stand point of safety.
Which brings me to my final point. Decks are a relatively recent componenent of a house. Historically it would be unusual to build a wooden structure unprotected from the elements. The lack of code guidelines and enforcement in this area is an embarassment to building codes as whole. The outstanding liability in shoddily built decks and even well built ones is staggering. For these reasons it is important that any deck is inspected periodically for safety. Like that ever happens.
Before you go ripping to hard on the lumber yard guy and contractors for using zinc fasteners, you should try selling anything but a nailed, treated, zinc fastener deck in my area. Quality is a tough sell to the majority of homeowners today. Granted, we do it, but it narrows our market quite a bit.
Tom
I am amazed that this has recieved six posts and no one has, as yet, pointed out that galvanizing is zinc. But there is a "hot-dipped" process which has a thicker and rougher coating of zinc. Perhaps this is what is being referred to.
My experience to decks is limited to a couple located less than 100 feet from the Pacific Ocean. I used brass screws. [3", flathead - Phillips head is better.] Stainless steel would do also. Both more expensive, of course, but eliminates maintenance and failure. I've removed galvanized/zinc plated 1/4" lag bolts from a mahogany hand rail and they looked like golf tees - no threads left. But inland, they should last a lot longer.
- Peter
Hot dipped galvanized nails, and galvanized nuts, bolts, washers and lags. No question about it. You wouldn't nail the deck together with brites, right? So why would you bolt anything together with regular hardware. That would be the last time I took any advice from that salesman.
Yep, I realized when I was writing the original message that zinc is common to both types, that's why I refered to one as 'brights'. The bolts I typically use have a rough galvanized coating. And I also use deck screws, not sheetrock screws, and very few nails. I figure the (slightly) higher cost of the better fasteners into the bid, and the customer either buys the whole enchilada or I go on to the next project.