Nails and pressure treated lumber

[Harold Piper]

What Is wrong with using regular nails with pressure treated lumber?

[Peter Quinn]

Regular nails? Do you mean plain steel? Pressure treated is used in outdoor or wet locations. It arrives very wet from the treatment process. Regular steel will rust quickly and loose strength. Also, the C in the ACQ is for copper, which reacts with steel (dissimilar metals) to cause regular nails to corrode quickly and loose shear strength.

[jerry nazard]

Harold,

ACQ treated lumber uses copper as one of it's preservatives, causing a galvanic reaction with steel fasteners. Double dipped galvanized fasteners will last longer in ACQ because they will rust out slower. Most fasteners marked "ACQ Compatible" simply have a heavy ceramic or yellow zinc chromate coating. They will also rust out slower. The only fasteners at this time that can last for a reasonable time in ACQ are stainless and of course copper, brass, and bronze.

From a builders standpoint, ACQ lumber is one of the stupidest products to come along in some time. However, on the bright side, if you eat any of it you won't get sick.

Best!

-Jerry

[Matt Ocel]

Harold -

Peter and Jerry have it dialed in.

Nowadays you should have no problem finding the proper fasteners. Also remember any mechanical fasteners such as joist hangers need to be ACQ compatable, but last I heard it nobody carries plain galv. anymore. At least not in my neck of the woods.

[John Maus]

Harold,

I concur. The more "galvanized" the fasteners are the longer the will hold up when exposed to ACQ treated lumber. Specifically look for G-185 fasteners. Avoid the fasteners that are labeled “electro-galvanized,” or are marked “G-60” or “G-90.” They were designed to be compatible with the old CCA preservative, and won’t hold up to the new ACQ wood. A G-60 rating means that there's 0.60 oz. of zinc per sq. ft. of metal. The G-60 and G-90 hot-dipped coatings are what we've been using until now. Currently, G-185 is the best galvanized protection that you can buy.

Any metal flashing used with ACQ lumber will also need to be carefully chosen. The most common flashing material, aluminum, is not compatible with ACQ. Either stainless steel or copper will be much more corrosion-resistant. A plastic product should also work fine.

Some people line joist hangers and beam cradles with plastic sheeting to prevent the wood from touching metal. I have used the self adhesive plastic made for sealing around window frames during installation. They actually make sticky tarpaper like plastic called Vycor Deck Flashing that is designed to wrap around joists to keep them from touching the treated lumber.

There's another corrosion issue that you should be aware of. If two pieces of dissimilar metal touch, that can cause corrosion and eventual failure. So, if you choose to use G-185 nails, , you’ll also need to use G-185 joist hangers—not stainless steel. If you opt for Stainless Steel post-brackets, remember to buy Stainless Steel bolts—not G-185 bolts.

Good Luck

John

[Jacob Reverb]

Harold,

Any metal flashing used with ACQ lumber will also need to be carefully chosen. The most common flashing material, aluminum, is not compatible with ACQ.

+1

In marine applications (or anyplace wet or dew-y, where galvanic corrosion is an issue) copper eats through aluminum like a hot knife through butter.

[John Keeton]

As a side note, when the switch to ACQ occurred, I watched with amazement at the blue borg. They failed to stock appropriate nails and deck screws for months. There is no telling how many decks were installed with non-galvanized nails. Hopefully, they were all at ground level!!

[Paul Girouard]

From a builders standpoint, ACQ lumber is one of the stupidest products to come along in some time.

Yup! Maybe the worst one , ever!