Stainless steel vs. galvanized

[dragoncar]

I got a good deal on some patio lights and will be stringing them up with wire rope and wire rope accessories (said in the voice of Hank Hill).  Anways, there are a lot of options out there, but generally SS is 2-10x the cost of galvanized (also called "zinc plated" or just generally "zinc finish," all of which I'm wary of).

Basic question:  For outdoor applications, do I need stainless steel wire rope, or will galvanized, vinyl coated be sufficient?  Same question on the attachment hardware. 

Follow up questions for anyone who has done this before:  do I really need the wire rope thimbles, turnbuckles, etc., or can I just make loops?  Any advice on wire thickness?  Should I run a single wire back and forth in a zig-zag, or cut the wire into separate lengths for each leg of the zig-zag?

[The Architect]

Stainless steel is needed if your parts contact any standard treated lumber. You can get specially treated lumber that is less toxic and won't corrode galvanized steel, but you'd need to talk to the manufacturer of the wood about that and I'm sure it's a premium.

If you're not going to touch *any* treated wood, just painted wood/Trex/trees/metal posts/etc, it shouldn't matter. Galvanized probably won't hold up as well in the very long term, but it should work fine.

[dragoncar]

Stainless steel is needed if your parts contact any standard treated lumber. You can get specially treated lumber that is less toxic and won't corrode galvanized steel, but you'd need to talk to the manufacturer of the wood about that and I'm sure it's a premium.

If you're not going to touch *any* treated wood, just painted wood/Trex/trees/metal posts/etc, it shouldn't matter. Galvanized probably won't hold up as well in the very long term, but it should work fine.

So screws into unknown wood should also be SS?

[Radagast]

Screws might not matter as much, but I'd think the SS wire rope would last much longer, especially if it is exposed to moisture. Galvanized basically has a sacrificial zinc coating which will oxidize before the the local steel has a chance to do so. However eventually it will disappear and can also be scraped off. Plastic coatings break down pretty fast, especially in sunlight, temperature variations, and any abrasion. S.S. is corrosion resistant all the way though to varying degrees depending on the type of steel. It will probably last 2-10 times longer. I prefer SS for things things like wire rope that are outdoors, thin, and have the likelihood of abrading. Stationary objects that won't rub would be ok galvanized.

[Dan_at_Home]

The galvanized would probably be ok especially if they are under a patio that is outside but covered.  Even if they are directly outside, galvanized will hold just fine for several years at least.  Stainless steel is safest option but it is probably about 10x more expensive as well.

 

[GuitarStv]

Stainless steel is needed if your parts contact any standard treated lumber. You can get specially treated lumber that is less toxic and won't corrode galvanized steel, but you'd need to talk to the manufacturer of the wood about that and I'm sure it's a premium.

If you're not going to touch *any* treated wood, just painted wood/Trex/trees/metal posts/etc, it shouldn't matter. Galvanized probably won't hold up as well in the very long term, but it should work fine.

My understanding was that hot dipped galvanized nails and screws are typically recommended for building with pressure treated wood.  Sure, they'll corrode eventually . . . but you're talking like 20 years in the future.

[VirginiaBob]

I'd say it depends on where you live.  In coastal areas, I'd go stainless.

[The Architect]

My understanding was that hot dipped galvanized nails and screws are typically recommended for building with pressure treated wood.  Sure, they'll corrode eventually . . . but you're talking like 20 years in the future.

What fasteners should I use with preservative treated wood?

    The Treated Wood Industry recommends the use of hot-dip galvanized or stainless steel fasteners for use with treated wood. ... You should not mix the use of hot-dip and stainless steel fasteners and connectors. ...

Everything you need to know, and some things you probably don't. Properly galvanized products might work with your treated wood. Older existing wood is likely an older, now illegal, treatment that will fare better. Newer treated wood is usually more corrosive, but there are way too many treatments to know over an internet forum. Galvanized is likely to look like junk in a few years either way.

[Greg]

Quality galvanized cable will outlast the lights.  Stainless is mostly for appearance in this application.  Galvanized cable will turn whitish grey over time.

I prefer galvanized myself for fasteners, often SS ones are soft and gall easily.  Depending on the load and span, 3/16" should work, if overkill.  For comparison, I built a zipline for my kind out of 5/16" galvanized cable, it's about 200' long and would support several adults if it weren't for the stretch.

However, if your lighting is grounding via the cable, use stainless or the connections will fail due to corrosion.  Even with stainless you may get some corrosion, as there are varying levels of purity in stainless.

[dragoncar]

Thanks, guys.  Greg's final comment notwithstanding, I went with stainless steel 3/16 uncoated at twice the price of 1/8 galvanized, vinyl coated.  The biggest issue I have with the galvanized is that I have no idea if it's "quality" -- hit dipped vs. electroplated vs. what.  Stainless steel has the same problem in that for many components I have no idea what kind of SS it is, but I just hope the quality is there.  This isn't a huge project, so either way the expense is minimal -- I just want to "do it right".

I think the lights themselves would probably handle the 25' span without help -- they are very heavy duty cable.  What I'm trying to do is use a "main line" to span about 200', and then have 25' zigzag segments between the house and the "main line."  I'm saying "main line" because I have no idea what this would be called in architectural/civE terminology ... it's not a guy wire, but that flavor.  It may not work, and I might have to install some posts instead.  I'm just wary of the posts because they will be more work, cost more, could be more unsightly/ugly, and could destabilize my retaining wall (since the below ground portion of the posts would be levering against the retaining wall unless I made them REALLY deep).

Decided to use 1/4' SS eye bolts to anchor into the house at the second floor girder.  Not sure if this will work well, but again, the load isn't high, and nobody's life is at stake.  Was considering carabiners at all connection points, but decided to go with turnbuckles just in case.

Crap, just realized I didn't order the clamps.  Trying to decide between simplex and duplex clamps -- any advice?  Simplex seems sufficient, but duplex is more bang for buck -- it's twice as many plexes!

http://www.ebay.com/itm/20-Stainless-Steel-Simplex-Wire-Rope-Clip-for-1-1-6-or-3-32-Wire-Rope-/151074320399?pt=LH_DefaultDomain_0&hash=item232cbb300f
http://www.ebay.com/itm/20-Stainless-Steel-Duplex-Wire-Rope-Clip-for-1-1-6-or-3-32-Wire-Rope-/161057771949?pt=LH_DefaultDomain_0&hash=item257fca91ad

[Greg]

I think you'll be fine with the simplex clamps for the span you're dealing with.  Pics or it never happened!

[dragoncar]

I think you'll be fine with the simplex clamps for the span you're dealing with.  Pics or it never happened!

Lol, your wish is my command.  I got the duplex cause I was like.. it's $5 more and I'll probably need to double up on the simplex in some places.  My turnbuckles are on a slow boat from China, so it may be a while before this project is completed!

By the way, I'm not ignoring your advice... I just keep getting it right after I make a purchase!

[Greg]

By the way, I'm not ignoring your advice... I just keep getting it right after I make a purchase!

I'm not offended...  I usually don't think to ask for advice until after I make a decision.

[TomTX]

There's a lot of difference between real hot dip galvanized and various zinc plate.  Plating is generally much thinner and has more porosity. Protection is proportional to thickness of the zinc given equal porosity.

[dragoncar]

As an update, I have all materials but the duplex clips are too small despite being listed as compatible with my rope size.  Not sure if this will turn into an eBay hassle or work out... If I have to get new ones from China it'll take another few weeks...

[Greg]

As an update, I have all materials but the duplex clips are too small despite being listed as compatible with my rope size.  Not sure if this will turn into an eBay hassle or work out... If I have to get new ones from China it'll take another few weeks...

When I built my daughter's zip line I found what I needed cable-wise at Home Depot.  I used two clamps at each end.  Surely this would hold some lights up.

[Radagast]

Yeah I was gonna say that. Any hardware store should have these materials, even little ones and farm supply-type stores.

[dragoncar]

As an update, I have all materials but the duplex clips are too small despite being listed as compatible with my rope size.  Not sure if this will turn into an eBay hassle or work out... If I have to get new ones from China it'll take another few weeks...

When I built my daughter's zip line I found what I needed cable-wise at Home Depot.  I used two clamps at each end.  Surely this would hold some lights up.

Home Depot has absurd prices on stainless steel, and no duplex clips.  I'll need like 15 of them so I'd like to save some bucks

[dragoncar]

I think you'll be fine with the simplex clamps for the span you're dealing with.  Pics or it never happened!

Well, it didn't happen in the spot I was originally planning due to support issues, but I used the simplex clamps and attached it to a fence instead.

[Greg]

Neat!  I bet it looks nice at night.