Yes, you can install composite decking on wooden joists, and many homeowners do just that. However, if you’re considering composite decking for its durability and low maintenance, you should also think about the longevity of your deck frame.
While composite decking can last 25 to 50 years, a pressure-treated wood frame may only last 10 to 15 years or even less in some cases.
At AdvantageLumber.com, we’ve seen a growing number of homeowners facing premature deck failure, not because of their composite decking, but because of their rotting wood deck frames. So, before you build a composite deck on a wooden frame, consider the risks and potential long-term costs.
The Problem with Pressure-Treated Wood Frames
Most people choose composite decking to avoid the maintenance headaches that come with softwood decking, such as pressure-treated pine. Wood decking requires regular staining, sealing, and upkeep to prevent rot, splintering, and yearly maintenance. But while composite decking eliminates these issues for the surface boards, it doesn’t solve the problem of the deck frame itself.
Your deck frame is the most important structural component, and when it’s made from pressure-treated lumber, it is highly susceptible to moisture damage, rot, and insect infestation. Unlike decking boards, most homeowners do not and realistically cannot apply a sealer or waterproofing product to their deck frame. As a result, we’ve seen pressure treated deck frames deteriorate in as little as 10 to 15 years, and in some cases, even sooner.
Why Pressure-Treated Wood Doesn’t Last Like It Used To
Older pressure-treated wood used a chemical treatment that contained arsenic (CCA – Chromated Copper Arsenate), which was highly effective at preventing rot and insect damage. However, due to environmental and health concerns, CCA-treated lumber was phased out for residential use in 2004.
The newer treatments such as ACQ (Alkaline Copper Quaternary) and MCA (Micronized Copper Azole) do not offer the same level of protection and tend to break down much faster, especially in high-moisture environments.
Over time, the newer pressure treated wood treatments allow water penetration, which leads to rot from the inside out. Even if your composite deck boards remain in great shape, a rotting wood frame can become structurally unsafe and require expensive repairs or a full rebuild long before your decking needs replacement.
Long-Lasting Alternatives to Wood Deck Framing
If you’re investing in composite decking for its longevity and low maintenance, why not choose a deck frame that lasts just as long or even longer? Here are three superior alternatives to pressure-treated wood framing:
1. New Castle Steel Deck Framing
New Castle Steel deck framing is one of the most durable and longest-lasting options available. Made from galvanized steel, it resists rot, mold, and insect damage and is engineered to last for decades without deterioration. It also provides superior strength and stability, reducing issues like deck movement and sagging over time.
2. Outdure Aluminum Deck Framing
Outdure aluminum deck framing is another top-tier option. Aluminum is naturally corrosion-resistant, lightweight, and incredibly strong. Unlike wood, it won’t warp, twist, or crack over time, ensuring your deck frame remains structurally sound for the lifespan of your composite decking.
3. TimberTech Aluminum Deck Framing
TimberTech aluminum deck framing offers exceptional durability and long-term performance. Designed specifically for outdoor use, this framing system is resistant to moisture, rust, and pests. It also pairs perfectly with TimberTech composite or PVC decking, creating a complete, high-performance deck system built to last.
The Bottom Line
While you can certainly install composite decking on a pressure-treated wood frame, it’s important to consider the long-term risks. If your deck frame deteriorates in 10 to 15 years while your composite decking is still in great shape, you’ll face costly repairs or even a full deck replacement. By investing in a steel or aluminum deck frame, you ensure that your entire deck both the frame and the decking stands the test of time.
At AdvantageLumber.com, we’ve seen firsthand how quickly pressure-treated deck frames can fail, and we highly recommend considering alternatives like New Castle Steel, Outdure aluminum, or TimberTech aluminum deck framing. These materials provide the durability and peace of mind that a composite deck deserves.
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