Most homeowners in the Chicago area don't realize their deck is failing until a railing gives way or a board splinters underfoot. But by then, the repair bill has already doubled. In 2026, after four brutal winters and a spring that swung between 40-degree rain and 80-degree sun, many decks in Cary, Arlington Heights, and across northern Illinois are showing damage that looks like normal wear but is actually structural decay. Here are five deck repair signs Chicago homeowners miss every year, and exactly what to do about them before they become expensive emergencies.
1. Rotting Wood That Looks Solid (But Isn't)
The trickiest part of rot is that it often hides beneath a painted or stained surface. You can run your hand over a joist or a rim board and feel nothing wrong. But take a screwdriver and gently poke the wood around the ledger board (where the deck attaches to your house), and you might find the tip sinks in a half inch with almost no pressure. That's rot, and it's been eating the wood from the inside out for months.
In the Chicago climate, rot concentrates in three places: the ledger board attachment points, the bottom ends of posts where they meet concrete footings, and the rim joist ends near downspouts. These areas stay damp for days after a rain because water pools or wicks up from the ground. A 2023 study from the North American Deck and Railing Association found that 40 percent of deck collapses involve rot at the ledger board connection. That's the piece bolted to your house. When it fails, the deck pulls away from the wall.
What to check: Grab a flathead screwdriver and a flashlight. Once a month during the growing season (April through October in Illinois), poke around every connection point. If the wood feels spongy or the screwdriver sinks in more than an eighth of an inch, you have rot that needs professional attention. Burns Carpentry's team sees this constantly during Deck Repairs in Cary and the surrounding suburbs. They'll cut out the rotted section and sister in new treated lumber, or replace the entire rim board if the damage is widespread.
2. Loose or Pulling Fasteners You Can't See
Your deck is held together by hundreds of nails, screws, and bolts. Over time, seasonal expansion and contraction in Illinois's freeze-thaw cycle work them loose. A screw that was flush with the wood surface five years ago may now sit a sixteenth of an inch proud. That doesn't sound like much, but it means the fastener has lost its grip. The deck boards are no longer locked in place; they're floating on top of the frame.
The danger here is invisible because you're walking on the boards, not looking at the underside. But if you go into your crawl space or basement and look at the joist ends, you'll often see nails that have backed out by a quarter inch or more. In extreme cases, the joist hangers themselves have pulled away from the ledger because the nails holding them sheared off during a heavy snow load.
How to spot it without crawling under the deck: Walk across the deck slowly. Listen for squeaks, and watch for boards that bounce more than their neighbors. A board that dips noticeably when you step on it is often attached to a joist hanger that's lost its fasteners. If you have access to the underside, check every joist hanger with a flashlight. Push on the hanger with your hand. If it moves even a little, the fasteners are failing. Burns Carpentry recommends having a professional inspect and tighten or replace all fasteners every three to five years, especially on decks built before 2020 that used standard galvanized nails instead of the stronger structural screws now required by code.
3. Subtle Shifts in Deck Post Alignment
Deck posts should be perfectly vertical. Even a two-degree lean is a warning sign that the footing below has shifted or the post has rotted at the base. In 2026, after the heavy snowfalls and rapid thaws of the past two winters, many Chicago area homeowners are seeing posts that have moved a half inch or more out of plumb.
The problem usually starts below grade. Deck footings in northern Illinois are supposed to extend below the frost line, which is roughly 42 inches deep in this region. But footings poured before the mid 2010s were sometimes shallower, and frost heave over multiple winters can push them upward or sideways. When the footing moves, the post goes with it. A post that leans by an inch or more has likely lifted its footing several inches, and the entire deck is now resting on unstable ground.
Quick check: Stand at one corner of your deck and look down the row of posts. Hold a level against each post. If the bubble is off center by more than a quarter inch over six feet, call a professional. Burns Carpentry handles deck repairs in Arlington Heights, Aurora, and Elgin where frost heave is a recurring issue. Their crew can excavate around the footing, reinforce it with a concrete collar, and reset the post to vertical. Ignoring a leaning post for even one more winter can triple the cost of the repair because the deck frame starts racking (twisting out of square), which damages joists and deck boards too.
4. Cracks That Signal Structural Damage, Not Surface Wear
Not all cracks are created equal. A hairline crack running along the grain of a deck board is usually cosmetic. But a crack that opens wider than a quarter inch, runs across the grain, or appears in the same place on multiple boards is almost always structural. These cracks happen when the wood has dried out too much, lost its internal strength, or been overloaded by snow or furniture.
The most dangerous cracks are the ones you can't easily see. Check the ends of joists where they rest on the beam. If you see a vertical crack starting at the top of the joist and running down, that joist is failing. It's called a shear crack, and it means the wood is no longer strong enough to support the load above it. In the Chicago area, where decks often hold snow loads of 30 to 40 pounds per square foot in winter, a cracked joist can snap without warning.
What to do: Take a photo of every crack wider than an eighth of an inch. Measure its length and note whether it's growing. If a crack appears on multiple joists or on the same joist in multiple places, do not use that section of the deck until a professional inspects it. Burns Carpentry recommends replacing any joist with a shear crack longer than six inches. The fix usually costs between $150 and $400 per joist in the Chicago market, far less than the $2,000 to $5,000 you'd pay for emergency repairs after a collapse.
5. Soft Spots Underfoot That Feel Like Normal Wear
This is the one homeowners rationalize the most. You walk across your deck and feel a slight give underfoot, a sponginess near the steps or around the grill area. You tell yourself it's just old deck boards, that they've always been a little bouncy. But soft spots almost never come from the deck board itself. They come from the structure below. The deck board is just the messenger.
When you step on a soft spot, you're compressing the joist or the beam beneath it. That compression happens because the wood has rotted, cracked, or been eaten by insects. In decks built with pressure treated lumber before 2010, the treatment often didn't penetrate the full thickness of the wood, leaving the core vulnerable to rot. A soft spot that feels like a slight dip today will feel like a trampoline in six months, and the board will eventually break through.
How to test: Walk every square foot of your deck in a grid pattern. Mark each soft spot with chalk or painter's tape. Then go underneath and look at the joists directly below those marks. If you see discoloration, fungal growth, or wood that crumbles when you touch it, the joist needs replacement. Burns Carpentry offers deck repairs in Chicago and Schaumburg that include sistering compromised joists with new lumber, often without removing the deck boards above. The cost typically runs $200 to $500 per joist, depending on access and the extent of the damage.
If you catch a soft spot early, before the joist fails completely, you can often patch the area with a new section of deck board and reinforce the joist from below. Let it go another season, and you're looking at replacing entire sections of decking and multiple joists. The difference in cost is roughly four to one, $300 versus $1,200 for a typical 10 by 10 foot section.
Frequently Asked Questions
How much does a deck repair typically cost in the Chicago area?
Most deck repairs in the Chicago area run between $300 and $1,500 for common issues like replacing a few joists, tightening fasteners, or fixing a leaning post. Full deck rebuilds or structural overhauls can cost $4,000 to $12,000. Burns Carpentry provides free estimates for all deck repairs in Cary, Arlington Heights, and the surrounding suburbs, so you know the exact number before any work starts.
Can I fix a soft spot on my deck myself?
You can replace a single deck board yourself if the structure below is sound. But if the soft spot comes from a rotted joist or beam, that's a structural repair that requires experience with load calculations, proper fastening techniques, and local building codes. Most homeowners in the Chicago area find that hiring a professional like Burns Carpentry for structural deck repairs saves time and prevents repeat failures.
How often should I have my deck professionally inspected?
Once a year, ideally in early spring before you start using the deck heavily. The freeze-thaw cycle in Illinois does the most damage between January and March, and a spring inspection catches the problems before summer entertaining season. Burns Carpentry combines deck inspections with their deck repair services, giving you a written report of what needs attention and what can wait.
What's the biggest deck repair mistake homeowners make?
Ignoring small problems because they think the whole deck needs to be replaced. Most decks in the Chicago area can be repaired for a fraction of the cost of replacement. A rotted ledger board, a leaning post, or a few cracked joists are all fixable. Homeowners who wait until the deck is unsafe end up paying two to three times more for emergency repairs.
If your deck is showing any of these signs, don't wait until next spring to act. Burns Carpentry handles deck repairs across Cary, Arlington Heights, Aurora, Chicago, Elgin, Joliet, Naperville, Palatine, Schaumburg, and Waukegan. They'll come out, inspect the structure, and give you a straightforward assessment of what needs fixing and what doesn't. If the damage is minor, they'll tell you. If it's serious, they'll quote the repair and handle the permits. Give them a call. Your deck has been through enough winters.
