# Carriage bolts for treated lumber



## BrownsFan (Jul 11, 2011)

We moved last October. (I hope to update shop photos soon.) My first outdoor project is re-constructing the kids' swing set we moved in large pieces. The carriage bolts that came with the original kit were badly deteriorated.

As I re-build, what is the most appropriate metal-type for AC2 pressure treated lumber. I don't want the expense of stainless so do you prefer zinc or galvanized?


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## crank49 (Apr 7, 2010)

I just checked the engineer's bible (McMaster Carr) and compared 4 popular materials, bronze, stainless steel, hot dipped galvanized, and zinc plated.

All bolts I checked were 5/16" x 2" long.
Bronze = $2.00 each
Stainless = $1.50 each
Hot dip galv. = $0.20 each
Zinc plated = $0.10 each

Given those numbers I would say hot dip galvanized would be the best value by far.
HD galv should last about 7 times as long as zinc, and only cost twice as much.


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## BrownsFan (Jul 11, 2011)

That's kind of where I'm leaning…. galvanized. any other opinions?


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## kdc68 (Mar 2, 2012)

+1 for galvanized


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## 1thumb (Jun 30, 2012)

I used to design and build wooden playsets. Hot dipped galvies


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## ajosephg (Aug 25, 2008)

Might want to read this. http://www.deckmagazine.com/decking/fighting-fastener-corrosion.aspx The bottom line seems to be that galvanized will eventually fail, leaving two alternatives. Stainless or Polymer coated.


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## BrownsFan (Jul 11, 2011)

Eventually… anything and everything will fail. Haha.

Speaking of coated fasteners- I plan to used coated deck screws. The galvanized screws supplied with the kit (about 7 years) ago were practically nails- lacking nearly all their threads. The coated deck screws ought to address this. Thanks Joe!

For the structure 4×4s, etc.. I think I will use galvanized carriage bolts. By the time the 5/16 thick carriage bolts fail, kids will be done with the swingset. The 7-yr old carriage bolts were still sound… just rusted nuts so tight my impact wrench wouldn't break them free. A few of the old posts are going to the burn pile because of this.


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## juniorjock (Feb 3, 2008)

Any bolt with a head on it (un-like carriage bolts) would be okay. At least you'd have something to get a wrench on when you need to change it out. Like they said, nothing lasts forever.


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