Steel vs. Wood Deck Framing: Why the Frame Matters More Than the Boards

Oct 10

3 min read

When people shop for a new deck, almost all the attention goes to the boards. Which color, which brand, which grain. That makes sense, since the boards are what you see.

But the part that decides how long your deck lasts is the part you'll never look at again once it's built: the frame underneath.

The problem nobody mentions

Today's composite and PVC boards come with fade and stain warranties of 25 to 50 years. Most of those boards are still screwed down to pressure-treated lumber, and pressure-treated joists in New Jersey usually start showing their age somewhere around 15 to 20 years in.

Wood framing doesn't fail all at once. It shows up slowly:

Joists twist and crown, so the deck surface gets wavy and boards start to look uneven
Water sits on top of the joists under the boards and rot starts at the fastener holes
Ledger boards and beams soften, which is a safety problem, not just a looks problem
Screws loosen as the wood shrinks and swells through our freeze-thaw winters

So you end up with 30-year boards on a 15-year frame. When the frame goes, the boards come off with it, and you're paying for a whole new deck.

What steel framing does differently

Steel deck framing uses galvanized and powder-coated steel joists, beams, and ledgers in place of lumber. A few things change right away:

It doesn't rot. Water, bugs, and mold have nothing to eat.
It stays straight. Steel doesn't twist, shrink, or crown, so the deck surface stays flat for good. That's especially noticeable on lighter-colored boards, where every bump shows.
It spans farther. Steel can cover longer distances with fewer posts, which means a more open space underneath. That's great for second-story decks with a patio below.
It doesn't burn. Steel framing is non-combustible, which adds peace of mind next to a fire pit or grill.
It matches the boards. The frame is built to last as long as the decking on top of it, so you don't rebuild from the bottom up halfway through the boards' life.

What about aluminum?

Aluminum framing has the same advantages as steel, plus one more: it doesn't rust at all. That makes it the safest choice for homes right on the water, where salt air is hard on anything with iron in it. It costs more than steel, so for most homes inland, steel is the better value. Down the Shore, aluminum is often worth it.

What does it cost?

Steel framing usually adds about 15 to 30 percent to the total price of a composite deck compared with wood framing, depending on the size and height. On a second-story deck the gap tends to be smaller, since a tall wood deck needs a lot of heavy lumber and bracing anyway.

Think of it this way. With wood framing, you'll likely be rebuilding the deck once while you live there. With steel or aluminum, you're building it one time.

Here's how the three options compare side by side:

When wood framing still makes sense

We still build plenty of decks on wood frames. It's a good fit when:

You're planning to sell in the next several years
The deck is small and low to the ground
Budget is the main concern

If we frame with wood, we protect the tops of the joists with joist tape, use properly coated fasteners, and flash the ledger correctly. Those details add years to a wood frame.

When steel is the better call

Raised and second-story decks
Decks over a patio or living space below
Homes you plan to stay in for the long haul
Coastal homes (aluminum)
Large decks where a flat, even surface matters

Build it once

Atlas Surfaces builds steel and aluminum-framed composite decks across South Jersey, the Jersey Shore, and Eastern Pennsylvania. We're NADRA-certified and Pros, and we'll walk you through both framing options on site so you can pick what fits your home and your plans.

Want to see what a steel-framed deck would cost for your home? Contact us for a free site visit.