How do I check whether my deck is safe?
Short answer
Once a year, walk the deck and get under it with a flashlight and a screwdriver. Probe the ledger, joist ends, post bases and stair stringers for soft wood. Look for rust on hangers and bolts, loose or missing bolts at the ledger and railing posts, and daylight between the ledger and the house. Push hard on every railing post and section. Bounce in the middle of the deck and at the stairs. Anything soft, loose, rusted through or moving is a reason to have a builder look.
Why an annual check matters here
Decks rarely fail all at once. They fail at one connection that has been quietly wet for years, usually the ledger or a post base, and then one day enough people stand on the edge for a photo. In coastal North County the marine layer and salt air keep connections damp and speed up corrosion, so the hidden parts age faster than the deck looks. An hour each spring with a flashlight is the cheapest insurance a deck owner can buy.
The balcony we rebuilt in North County is the standard case. From the yard the problem was a railing shedding pickets. Underneath, the joist ends and ledger area had rotted where water had sat behind an unflashed connection. The owner found out before anyone got hurt, which is the whole goal of this list.
The walk-through: on top
- Bounce in the middle of the deck and near the house. Some give is normal; a trampoline feel or a creak at the ledger is not.
- Push hard outward and sideways on every railing post, then on each rail section. Movement of more than a wobble means the post connection is loose or the wood is soft.
- Check that no opening in the railing passes a 4-inch sphere, including under the bottom rail and at the stair.
- Look at the boards for cupping that holds water, splits at the ends, raised fasteners and soft spots; press with your heel at board ends.
- Walk the stairs. Treads should not flex; the handrail should be solid and graspable; the bottom step should land on concrete, not dirt.
- Look at where the deck meets the house for staining, soft stucco or trim, or a gap that opens when someone jumps.
The walk-through: underneath
- Probe the ledger with a screwdriver every couple of feet, and the rim joist of the house above it if you can reach it. Look for bolts or lag heads along the ledger; nails or screws alone are a red flag, and so is no visible flashing.
- Probe every joist end at its hanger, and the tops of the joists where you can reach between boards.
- Probe post bases and the first few inches of each post. A post in soil or in a planter is a problem regardless of how it probes.
- Probe beam ends where they sit on posts and look at the connector; beams resting on a notch with a nail or two are common on older decks.
- Check stair stringers at the bottom and at the top connection, which is often under-built.
- Look at every piece of metal for rust: hangers, joist hanger nails, bolts, post bases, railing brackets. Surface rust is a note; flaking or holes mean replacement.
What different findings mean
Soft wood at a joist end or a stringer is usually repairable by sistering or replacing that member. Soft wood at the ledger or in the house framing behind it is a bigger job and a priority, because that is the connection that holds the deck up. Buried posts can sometimes be cut back and set on new bases if the footing is sound. Loose railing posts need a proper bolted connection with blocking, not more screws. Rusted-through hangers get replaced with new galvanized or stainless ones one at a time with the joist supported.
If you find something that worries you, keep people off that part of the deck until it is looked at. Large gatherings load a deck far more than daily use, and the edge is where people cluster.
When to bring in help
Anyone can run this list. Call a builder when a probe finds soft wood you cannot see the extent of, when the ledger has no visible bolts or flashing, when posts are buried, or when a railing moves. We do these evaluations by pulling a few boards and probing the frame, and we will tell you whether it is a repair, a partial rebuild or time to start over. A general home inspector will also flag these items at a sale, so it is better to know first.
Related questions
How often should a deck be inspected?
A homeowner walk-through once a year, ideally in spring, and a closer look by a builder every several years or whenever you find soft wood, movement or heavy rust. Older decks and decks near the ocean deserve more frequent attention.
What is the most common deck safety problem you find?
The ledger: screwed or nailed through stucco into little or nothing, with no flashing, and rot behind it. Second is posts buried in soil. Both are hidden from the deck surface and both are what cause collapses.
Is a bouncy deck dangerous?
Not necessarily, but it is a sign the frame is under-sized, over-spanned, or losing stiffness to rot or loose connections. A deck that has become bouncier over the years, rather than always being that way, should be probed.