# Epoxy coated lag screws?



## Abandoned Barns (Dec 25, 2012)

What's the deal with these? I was told by an engineer (a civil engineer but still an engineer) that because PT was now made w/copper, I needed epoxy coated lag screws so they wouldn't react w/the copper. Their pretty pricy, but they'll be holding a porch roof over my family's heads. 

Is this right or is my friend being a little overly engineer-ish? 

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## simi-steading (Sep 27, 2012)

I've recently started using them.. The ones I've been using are called LedgerLok... I really like them... they go in SO much easier with just a regular cordless drill, even when you're talking a 6" lag... I've been using them for most of my projects lately... a little more expensive, but no worries about corrosion either.. I can't talk to the copper content.. I know nothing about that.. I just know they work well, and no worries about corrosion..


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## Harry Chickpea (Dec 19, 2008)

You are talking about galvanic corrosion and corrosion from other components of the preservative.

The amount of copper near the screw is minimal, but with moisture thing can migrate.

A little searching turned up this article which explains the issue:
http://www.deckmagazine.com/decking/fighting-fastener-corrosion.aspx

I know though that some of my deck screws, which are coated, have failed and snapped. My advice would be to size up on any metal and consider zinc coating.


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## Abandoned Barns (Dec 25, 2012)

Is it the same purpose for the ceramic coated screws? 

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## wharton (Oct 9, 2011)

Simi has it right. They are a pretty impressive product, I've used hundreds of them in the last few years on deck ledgers. They are also impressively strong. The boxes list the shear value in various woods. They are far stronger than 3/8" galv. lags in this application. BTW, your engineer is wrong. Simpson and other manufacturers offer a large line of fasteners and hardware that are galvanized, and rated for direct contact with the latest PT formulations. Simpson calls their stuff, "Z-MAX" and most building suppliers now stock lots of heavily galvanized bolts, nuts and lags. Carriage bolts are no longer acceptable as they have too small of a head, and can be drawn through the material as a failure mode. Galvy washers and hex head bolts are now required for these applications.


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## texican (Oct 4, 2003)

Trust me, use approved screws... I screwed my steel roofing on my barn, and ran out of 2x6's for the decking and used PT wood... the metal rotted completely out over the first winter.

Screws, even approved ones, are cheap, compared to having to replace an entire roof.


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