The numbers inspectors check
The North American Deck and Railing Association (NADRA), which is based in Quakertown, publishes a deck evaluation checklist for professionals. These are the reference figures it uses for stairs and railings. Your town's adopted code edition decides what actually applies, so treat them as a screening list, not a pass or fail ruling.
- Guards: required where the walking surface is more than 30 inches above grade, and at least 36 inches tall for most homes.
- Gaps between balusters: under 4 inches on the deck guard and under 4 3/8 inches on the stairs.
- Stair handrail: 34 to 38 inches high, shaped so a hand can wrap around it, and ending at a post or safety terminal rather than a loose end.
- Steps: within one flight, the tallest riser and shortest riser (and the deepest and shallowest tread) shouldn't differ by more than 3/8 inch. Open risers shouldn't let a 4-inch sphere through.
- Stairway and landing: at least 36 inches wide, with a landing at least 36 inches deep in the direction you walk.
A tape measure from a safe spot can answer most of these. An older deck can come up short even if nothing is broken, because NADRA notes that guard, handrail, stair and lighting rules get updated as codes change, typically every three years.
What you can spot without testing it
NADRA's Check Your Deck consumer checklist says railings should be firmly held in place, stair risers and stringers (the sloped boards that carry the steps) should be securely attached and not decayed, and the stairs shouldn't sag, sway or look uneven. Look for:
- Rust stains, popped nails or missing screws at the post bases and where the stringers meet the deck.
- Dark, split or soft-looking wood at the bottom of posts and at the stringer ends, especially spots that stay damp.
- A top rail pulling away from its post, or balusters that are cracked or missing.
- Planters, toys or wet leaves on the stairs, which NADRA flags as trip and slip hazards, and burned-out stair lights.
Do this by eye from solid ground. Don't lean on a suspect railing, bounce on the steps or crawl under the stairs to look. If a post or stair is visibly loose or broken, keep people off it until it's been looked at. Our guide to checking deck joists and posts covers the framing underneath.
Why a loose post isn't a quick screw fix
A guard post has to carry a person's weight from any direction into the deck frame. Trex's guardrail post installation guide calls that a critical connection set by code, with requirements for sideways loads from multiple directions. NADRA's evaluation checklist notes that in testing, posts held only by bolts or lag screws, and notched posts, failed the load and deflection criteria. The fix may be new blocking or hold-down hardware inside the frame, not another screw at the top. The checklist also calls the stringer-to-deck attachment a critical structural connection, and stairs hung on nails alone are a red flag.
Who to call and what to ask
For a safety opinion, NADRA's deck safety page recommends an ASHI-certified home inspector or a knowledgeable deck builder for older decks. Ask them to:
- Measure guard height, baluster gaps, handrail height and riser variation against your township's current code.
- Say how the guard posts and stringers are attached to the frame, and whether that can carry the required load.
- Put findings in writing, including what they couldn't see, and whether the stairs are safe to use until repairs are done.
Replacing a railing or rebuilding stairs may need a permit. Our guide on deck repair permits in Philadelphia and Bucks County explains where to check, and the contractor hiring checklist covers what to confirm before you sign.