Pressure-Treated Lumber Has Changed — What 2026 Homeowners Should Know Before You Build

In 2026, “pressure-treated wood” isn’t the same as what deck builders used decades ago. New preservatives, drying requirements, and treatment standards mean you need to pay attention — especially if you want your deck to last and look good.

Here’s what’s different now, and what South Jersey homeowners (Marlton, Mullica Hill, Deptford, Cherry Hill, Voorhees, Berlin, Williamstown, etc.) should keep in mind if you’re using treated lumber for framing.

🔧 What Changed — And Why It Matters

• New preservatives: MCA, ACQ, CA instead of CCA

Older decks often used lumber treated with Chromated Copper Arsenate (CCA). But after 2003, that was phased out for residential use. Modern treated wood now usually uses chemicals like Micronized Copper Azole (MCA), Alkaline Copper Quaternary (ACQ), or CA — still designed to resist rot, insects, and decay. That’s great for durability. But because the new treatment processes use water-based chemicals, the lumber comes out saturated and often very “wet” — which changes what you can do immediately after purchase.

• Drying time matters — don’t rush staining or sealing

Because treated wood arrives loaded with water, it's critical to let it dry thoroughly before sealing, staining, or painting. If you try to finish it too soon, paint or stain won’t adhere properly — and you could end up with peeling, warping, or uneven color. In many cases, that drying period can take weeks to several months, depending on humidity and weather conditions.

• Lumber quality and selection — know what you’re buying

“Pressure-treated” isn’t a one-size-fits-all label. There are different grades and use-cases: some boards are “above-ground only,” others are “ground-contact.” For deck framing — especially posts, joists, or any part that touches or nears soil — you want wood rated for “ground contact” or the proper use category under standards. Also: higher-grade lumber (fewer knots, cleaner edges) performs and lasts better — especially if the wood will be exposed.

• If you build with treated lumber — proper fastening & moisture care are essential

Because modern preservatives are copper-based, they can be more corrosive to standard fasteners and hardware. That means you need corrosion-resistant screws, bolts, and hangers (hot-dip galvanized or stainless) to avoid premature rust. Also — make sure wood is dry before painting or sealing. Many pros now use kiln-dried-after-treatment (KDAT) lumber when possible, because it dries faster and stays more stable (less shrinkage, warping, or “fastener smile”).

🏡 What This Means for South Jersey Deck Owners

If you’re building a deck now — or replacing an older one — using modern pressure-treated lumber can give you durability and longevity (20–40 years or more) — but only if handled correctly. A hastily built deck with wet wood, wrong fasteners, or sub-par lumber is a recipe for early failure.

At C-JAM Construction L.L.C., we’re aware of these changes. We pick appropriate lumber, let it dry when needed, use correct hardware, and build your deck to modern standards. If you live in our area and want a deck built or upgraded the right way — check out our prior posts on deck framing and structural integrity then get in touch at 609-302-0249.

Building smart now saves headaches — and prevents costly repairs later.