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Q.What type of gun nails should you use with ACQ plates and mudsills? Is it necessary to use stainless steel and then switch back to regular nails for regular lumber?

A.Tim Uhler, a lead framer for Pioneer Builders in Port Orchard, Wash., responds: Unlike the CCA (chromated copper arsenate) material they've replaced, the new pressure-treating chemical compounds — ACQ (alkaline copper quat), ACZA (ammoniacal copper zinc arsenate), CA (copper azole), and CC (ammoniacal copper citrate) — are very corrosive. Since conventional fasteners aren't compatible with this current crop of pressure-treated lumber, you'll need to use either hot-dipped galvanized or stainless steel fasteners.

Because my crew frames new homes, this issue affects how we fasten joists, rims, and sheathing to treated mudsills. Our initial response was to switch to hot-dipped galvanized stick nails when we were working with mudsills (stainless steel fasteners are just too expensive), but it's a big hassle to change fasteners every time you want to nail into the sill. Also, there still seems to be some question about how well these fasteners stand up to the new pressure-treating chemicals over time.

Several months back, we stopped using pressure-treated lumber altogether and started using lumber treated with SBX (sodium borate) for sills. Borate-treated wood resists insects and rot and is nontoxic to humans and the environment. It's not appropriate for decks or ground-contact applications, but it's fine for mudsills because they're protected from water. And since borate-treated lumber doesn't corrode fasteners, we were able to go back to using conventional nails for the entire frame.

There's one drawback to borate-treated lumber: It should not be exposed to the weather for very long, because the borate can leach out if it stays wet. Manufacturers indicate that it's okay for borate-treated lumber to be exposed to the weather during the "normal" construction process, but they don't say exactly how long that is; my understanding is that they're talking months rather than weeks. Our houses are dried in within three weeks, and when borate-treated material is on site we keep it under tarps.

Some building inspectors aren't familiar with borate-treated lumber, so be sure to get their approval before using it.

On those rare occasions when we have to use pressure-treated lumber, we use framing hardware with extra corrosion protection, such as Simpson's ZMAX (800/999-5099, www.strongtie.com) and USP's Triple Zinc G-185 (800/328-5934, www.uspconnectors.com) connectors, as well as both companies' more heavily coated hot-dipped galvanized fasteners.