What a Deck Inspection Typically Covers

What this covers

• The Damage You Can See Is Rarely the Problem

• Start With the Ledger

• Then the Post Bases

• The Screwdriver Test

• What the Age of the Deck Tells You

• Surface Problems Versus Structural Problems

• Springy and Wobbly Mean Different Things

• The Railing Is Not Cosmetic

• When Repair Stops Making Sense

• What a Real Inspection Covers

• The Short Version

Come home after a long stretch away and the deck is the part of the house that aged while you were gone. Everything else was inside, dry, and holding still. The deck sat out in the weather with nobody standing on it.

Most people look at a tired deck and see the gray boards, the lifted splinters, the peeling finish. Then they price refinishing, which is the wrong first move, because the surface tells you almost nothing about whether the thing is safe.

Here is what actually matters, roughly in the order a professional checks it.

The Damage You Can See Is Rarely the Problem

Weathered decking is a cosmetic condition. Boards go gray because sunlight breaks down the surface fibers. That is ugly and it is not structural.

The failures that hurt people happen in the parts nobody looks at. The connection to the house. The bases of the posts. The hardware holding joists up. All of it either tucked behind something or close to the ground, and all of it out of sight precisely because it is doing the structural work.

So a deck can look terrible and be perfectly sound, or look freshly stained and be one load away from letting go. Appearance and safety are close to unrelated on a deck, which is the single most useful thing to understand about them.

Start With the Ledger

The ledger is the board bolted to the house that the deck frame hangs off. When a deck collapses, this is overwhelmingly where it starts, and it fails for two reasons that compound each other.

The first is fastening. Older decks were often nailed on. Nails hold badly against being pulled straight out, which is exactly the direction a loaded deck pulls, and that loading is cyclic as people move around. Modern practice is through-bolts or structural screws in a specified pattern, because they resist pull-out in a way nails never did.

The second is water. The ledger sits tight against the siding, which makes a seam that water wants to get into. Without proper flashing above it, water runs down the wall, gets behind the board, and sits there against both the ledger and the house framing. Nothing shows on the outside while the wood behind quietly turns to pulp.

You cannot usually inspect this from above. What you can do is look underneath, from the yard, where the deck meets the wall. Dark staining on the siding below the deck line, a visible gap, rust streaks, or any sign of water tracking down is worth taking seriously. So is the absence of visible metal flashing.

Then the Post Bases

Second place for real failures, and easy to check.

Posts should not sit directly on soil or in a puddle of concrete that holds water around them. The standoff detail, where a metal base lifts the post slightly clear so water can drain and air can get in, exists because wood in permanent contact with wet ground has a limited life no matter what it was treated with.

Grab each post and push sideways, firmly. There should be no movement at the bottom. Look for dark soft wood at the base, a post sitting in dirt, or planting growing up tight against it.

The Screwdriver Test

This one takes ten minutes and it is the test that actually finds rot.

Rot softens wood before it changes its color much. A board can look fine and be gone underneath. So you probe it.

Take a screwdriver or an awl and press the tip firmly into the wood. Sound wood resists and you feel it stop. Rotten wood takes the tip in like firm cheese, sometimes half an inch with light pressure.

Where to probe:

• The ledger, anywhere you can reach it

• The bases of all posts, especially on the shaded side

• Joist ends where they meet the ledger or beam

• Anywhere water sits, under planters, below a step, in a corner that stays damp

• Stair stringers where they touch the ground

If the tip sinks anywhere structural, stop assessing and get somebody out. One soft joist end is a repair. Soft wood at the ledger is not a project you keep using the deck during.

What the Age of the Deck Tells You

Age is a shortcut to knowing which failures to look for first, because building practice changed inside the lifespan of a lot of standing decks.

Older structures are far more likely to be nailed at the ledger rather than bolted, and more likely to have no flashing above that connection at all. Both were common once and neither is acceptable now. If a deck predates the current approach, the ledger moves to the top of the list regardless of how the rest of it looks.

There is a second change that catches people out. The chemistry of pressure treated lumber was reformulated in the early 2000s, and the newer treatment is harder on metal than the old one was. Plain or lightly coated fasteners in contact with newer treated wood corrode faster than the same hardware would have in older lumber. On a deck built around that transition, or repaired with new lumber and old leftover hardware, the fasteners are worth a close look even where the wood is sound.

None of this means an old deck is unsafe. It means the inspection has a different starting point, and knowing the approximate build year saves a great deal of guessing.

Surface Problems Versus Structural Problems

The top three are a weekend. The bottom four are somebody with a flashlight and a pry bar.

Springy and Wobbly Mean Different Things

People describe both as “the deck feels off” and they are unrelated faults.

Springy is vertical. The floor flexes when you walk. That is usually a joist spanning further than it comfortably should, or a joist that has lost strength to rot. Unpleasant, often not dangerous, sometimes fixed by adding blocking or a mid-span beam.

Wobbly is sideways. The whole structure sways slightly when people move across it. That is a lateral bracing problem, and on a raised deck it is the one to take seriously, because the sideways force on a tall deck acts through a long lever onto the connections at the bottom.

A deck that does both, especially one more than a few feet off the ground, is telling you the frame is not doing its job.

The Railing Is Not Cosmetic

A railing that moves when you lean on it is a failed safety component, not a loose fitting.

Railing posts take a surprisingly large sideways load, because that is what happens when somebody falls against one. The weak point is almost always where the post attaches to the frame, and the common error is a post bolted only through the decking or the rim with too little holding it. If a railing post rocks, treat that stretch as out of use until somebody has looked at the attachment from underneath.

This matters most on the parts of a deck that are highest off the ground, which tends to be the far corner, which tends to be where everyone stands to look at the view.

When Repair Stops Making Sense

Repair is usually the cheaper answer and not always. The honest test is how much of the structure is involved.

The trap is sequential repair. Fix the boards this year, a post next year, the stairs the year after, and you spend more than a rebuild would have while still owning an old deck. Anyone at that stage is better off getting an honest read on whether to repair or replace before committing to the first stage of it.

What a Real Inspection Covers

If you bring somebody in, the visit should include the underside. An assessment done entirely from on top of the deck is not an assessment, because every failure listed above lives underneath.

Expect them to get under it where there is access, probe the ledger and post bases, check the hardware, look at how the stairs are attached and how the railing posts are held. Expect questions about the deck’s age and whether the siding has ever been off.

What you should get back is a split between what is a safety matter now, what is maintenance, and what is cosmetic. Anybody who quotes refinishing without having looked under the structure is quoting on the part that does not matter. Deck repair in Kent and the surrounding towns covered by their listing in Kent tends to start with the ledger for exactly this reason.

The Short Version

Ignore the boards for a minute. Push every post. Probe the ledger, the post bases and the joist ends with a screwdriver. Lean on the railing.

Ten minutes of that tells you more about whether your deck is safe than a season of looking at it from the kitchen window. The gray boards can wait. The connection to the house cannot.