Understanding South Jersey Deck Codes: Joist Spacing, Beam Sizes & Guardrail Rules

If you’re thinking about building (or rebuilding) a deck — whether in Marlton, Mullica Hill, Cherry Hill, Deptford, Voorhees, Berlin or elsewhere we serve — knowing the basics of New Jersey’s deck codes can save you headaches — and ensure your deck isn’t just pretty, but safe and built to last.

Here’s a homeowner-friendly breakdown of the code guidelines you should be aware of before you build or sign off on a deck job.

📏 Joists, Beams & Footings — The Structure Matters

• Joist spans & spacing: Deck framing in NJ must follow standards outlined in the code (see tables in Section R507 of the International Residential Code — adopted by NJ).

• Beam size & span rules: Beams need to be sized depending on the load (deck size, live load, etc.), joist span, and the number/spread of support posts. Over-spanning beams or undersized girders are common causes of sagging, deck bounce, or structural failure.

• Footings & posts: Footings must go deep enough (below frost line), and posts must be correctly sized and anchored — especially if the deck is elevated.

Poor framing or skimping on structural integrity is a recipe for a deck that fails early — good joists/beams/footings is where durability and safety start.

🛡️ Guardrails, Stairs & Safety Features — What Code Says

• For decks more than ~30" above ground: you must have a guardrail (often referred to as a “guard”). Standard requirement for residential decks: guardrail height ≥ 36 inches above the deck surface.

• Open-side guardrails or stairs/landings: the openings between balusters or rails must be small enough so a 4" sphere cannot pass through — to prevent falls or children slipping through.

• Staircases need minimum width (often 36"), consistent tread/riser dimensions, secure handrails between ~34–38" above tread nosing, and proper fastening.

These rules exist not just for inspections — but to keep you, your family, and visitors safe. Falls from decks and stairs can lead to serious injuries, and code compliance isn’t optional.

💡 What This Means — For You as a Homeowner

Building or replacing a deck isn't just cosmetic — it's investing in a safe, long-lasting structure. Even a deck that looks fine on the surface needs proper framing, footings, guardrails/stairs built to code so it holds up under load, weather, and over time.

If you want a deck that’s done right — structurally sound, code-compliant, and reliable — it helps to work with a contractor who knows the rules and prioritizes build quality. At C-JAM Construction L.L.C., that’s exactly what we focus on. Between checking joist/beam dimensions, footing depth, railing safety, and compliance — we build decks that stand up to South Jersey winters, summer heat, and decades of use.

If you’re curious about framing methods, materials, or want to see what a properly built deck looks like (vs. a DIY-job), check our past post on deck framing and structural integrity.