Most people check a deck by standing on it, but the parts that fail first are underneath and where it meets the house. This guide covers the 10 warning signs, how serious each is and a walk-around you can do yourself. It is homeowner guidance, not a professional inspection. NADRA says its own checklist "is not a substitute for a professional deck inspection."
Signs your deck is unsafe: the short list
Ten things mark an unsafe deck, and the most serious ones are under and behind it, not on top. Simpson Strong-Tie, the connector maker, groups the warning signs into five kinds: missing connections, loose connections, corrosion, rot and cracks. NADRA's homeowner list adds split or decaying wood, soft spongy spots, fasteners that pop or corrode, and a deck or stairs that sag or sway.
The "how serious" column below is our summary of what the cited sources say about each sign. No source publishes a rating scale like this, and it does not replace an in-person inspection.
| Sign | Usual cause (per sources) | How serious (our summary of the sources) | What to do |
|---|---|---|---|
| A ledger pulling away from the house | Nails only, missing flashing, rot, ledger on brick veneer | Highest | Nail heads only: NADRA says treat as unsafe, inspect now |
| A sagging structure | Rotted joists or beams, settled posts, no bracing | High | Get it inspected (Decks.com: even a slight sway) |
| A cracked beam | Aging, weathering, heavy loads | High in a beam, post or ledger | Have it checked; probe for rot |
| Rusted joist hangers | Corrosion, some wood treatments, mixed hardware | High if red rust won't wipe off | Evaluation before continued use (ICC) |
| Soil eroded at the footings | Runoff, disturbed soil, clay shrink-swell | Medium to high | Check posts for lean and gaps |
| Rotting, loose stairs | Rot, stringers on a slab, loose connections | High | Don't use until checked |
| A wobbly railing | Weak post connection, rot at the post base | High | Replace if it moves over an inch or two (JLC) |
| Soft, spongy wood and termite signs | Wood staying wet or touching soil | High in framing | Probe it; pest pro for mud tubes |
| Raised boards and popped nails | Loads and temperature changes | Low to medium | Drive down or replace fasteners |
| Severe splintering | Sun and weathering | Low alone | Sand or replace the worst boards |
The 10 warning signs, what causes them and how serious each is
Start with the connections that hold the deck up (ledger, beams, hangers, footings), then the parts people touch (stairs, railings, boards). A splintered board can hurt a foot; a failed ledger can drop the whole deck.
A ledger pulling away from the house
A ledger pulling away from the house is the sign the sources take most seriously. The ledger is the board fastened to the house that the joists hang from. Look for a gap opening at the wall, water stains or soft wood behind it.
NADRA estimates that 90 percent of deck collapses come from ledger connection failures, and says that if nail heads are the only hardware you can see, "consider it unsafe and have it inspected immediately." Washington State University research also found that a ledger with too few fasteners is a main failure point. The full ledger check is in its own section below.
A sagging structure
A deck that sags, bounces or sways when people move on it has a problem in its frame or its supports. NADRA says the deck and stairs "should not sway or move when tested." Decks.com's inspection checklist goes further: even a slight sway warrants a professional inspection.
Common causes are rotted joists or beams, settled posts and missing bracing; Fine Homebuilding says posts on decks 2 feet or more off the ground need diagonal bracing. No source gives a sag limit you can measure, so treat any visible dip or sway as a reason to get it looked at.
A cracked beam
A crack in a beam, post or ledger is more serious than a crack in a deck board. Simpson says large or numerous cracks can weaken a deck. The USDA Forest Products Laboratory explains that weathered wood first changes color and checks slightly, then develops deeper checks and cracks near the board ends.
Small checks on top of a board are normal aging. A long split through a beam, or one with soft wood around it, is the kind to have checked; Simpson's homeowner sheet says to consult a structural engineer or contractor if you're unsure.
Rusted joist hangers
Red rust on joist hangers, nails and other connectors is a safety warning, not just a cosmetic issue. An article in the ICC's Building Safety Journal says that if the rust wipes off there may be no actionable issue yet, but if it doesn't, the nail shanks are likely rusted and the wood may be decaying. The authors say the deck then needs an in-depth evaluation by a qualified person before it keeps being used, and that this risk "also applies to most decks," not only those by the coast.
Why it happens: the copper in modern wood preservatives can speed up corrosion of steel fasteners, and the DCA 6 guide notes that metal in contact with some treatments showed high corrosion rates in accelerated tests. DCA 6 calls for galvanized (G-185 if hot-dipped before fabrication) or stainless connectors, with fasteners of the same material.
Soil eroded at the footings
Soil eroded at the footings, or a footing that has sunk or lifted, means the deck's support is moving. JLC's deck-builder checklist flags footings that heave or drop, and says dropping often comes from footings poured on disturbed soil such as backfill. Decks.com adds that decks sink when footings sit on soil that was not properly compacted.
Look for soil washed away around the concrete or a post that no longer sits tight on its footing. DCA 6 calls for footings on undisturbed soil at least 12 inches below the ground. No source says how much erosion is too much, so treat any undermined footing as worth checking. See our guide to deck footings in Dallas clay.
Rotting, loose stairs
Stairs that rock, flex or have soft treads are a real injury risk. In an industry analysis of federal ER data from 2003 to 2007, stairs accounted for 1,950 of the injuries from structural failures, and railings 11,120. NADRA's homeowner check says stairs should be secure, and open risers should be no more than 4 inches.
A common hidden cause is stringers resting on a patio slab. DCA 6 says stringers shall not bear on concrete pads or patios unless they are founded at least 12 inches below undisturbed ground. Probe the bottom of each stringer, where water sits.
A wobbly railing
A railing that moves when you push on it is one of the most dangerous signs, because people lean on it without thinking. JLC's deck-builder source says to replace a railing with movement of more than "an inch or two at the top." WSU research found the connection between the railing post and the deck fails at low loads.
In the 2003 to 2007 injury analysis, railings were about one third of structural-failure injuries (calculated from Legacy Services' Table 2: 11,120 of 33,270).
Soft, spongy wood and termite signs
Wood that feels soft or spongy underfoot, or that a screwdriver sinks into easily, is likely rotting. NADRA lists soft spongy areas on its homeowner check. The USDA says serious decay happens only when wood stays above its fiber saturation point (about 30 percent moisture on average), and wood kept air-dry will not decay. So rot shows up where water sits: post bases, joist tops under boards, the ledger and stair stringers.
Termite signs, per Texas A&M's Urban and Structural Entomology Program, are wood that sounds dull when struck with a screwdriver, mud-lined galleries and mud shelter tubes. Mud tubes are a job for a pest professional.
Raised boards and popped nails
Raised boards and popped nails are mostly a trip hazard, but they can point to something worse. Simpson says loading and temperature changes loosen connections over time. NADRA's check covers fasteners that "pop," loosen or corrode.
Consumer Reports says to nail or screw down any fasteners you see popping up, and to tighten loose fasteners or replace rusty ones. If a nail keeps working loose, probe the wood around it.
Severe splintering
Severe splintering is usually weathering, not structural failure. The USDA's Wood Handbook says sunlight breaks down lignin at the wood surface and that wood fibers slowly erode, about 1/4 inch (6 mm) per century. Fine Homebuilding's advice is to sand or carve the splintering spots and replace the worst boards.
To tell weathered wood from rotten wood, use Decks.com's pick test: pry up a sliver. If it bends slowly and doesn't splinter much when it breaks, that signals decay.
How to inspect your deck, step by step (NADRA's checklist plus the structural checks)
Walk the deck in this order: under it, at the house, the frame, the stairs, the railing, then the surface, with a flashlight, a flathead screwdriver and a helper. This walk-around is based on NADRA's homeowner checklist, with the ledger, lateral and guard checks from the American Wood Council's DCA 6 guide added.
- Look under the deck first. Check every footing and post for washed-out soil, lean, or a footing that looks lifted or sunk. NADRA's evaluation form wants footings sunk 12 inches or more into undisturbed ground.
- Check the ledger at the house. Look for bolts or lag screws, not just nails. Look for metal flashing over the top. Check for gaps, stains or soft wood, and confirm the ledger is not hung on brick or stone veneer.
- Look for lateral connections. Metal hold-downs that tie the deck frame to the house framing (see the ledger section below).
- Check joists, beams and hangers. JLC notes the IRC calls for metal connectors where joists meet the ledger, so look for them rather than toenailed joints. NADRA's evaluation form also looks for 1½ inches of joist bearing. Wipe any red rust. If it doesn't come off, flag it. Probe joist ends and tops for rot.
- Check the stairs. Push on the stringers and stand on each tread. Look at where stringers meet the ground and the deck. Check for a handrail if there are four or more risers.
- Push the railing. Have your helper watch while you push hard on the top of each guard post. More than an inch or two of movement is a fail by JLC's rule.
- Walk the surface. Look for popped nails, loose or raised boards, splinters and soft spots.
- Clean up. NADRA says to clean away leaves, branches and other debris.
If you find any of the high-seriousness signs, stop there and get a professional to look.
The screwdriver probe test: how to check deck wood for rot
Push a flathead screwdriver into the wood; if it sinks past 1/8 inch without much resistance, the wood is probably rotted. Consumer Reports, quoting inspector Bruce Barker, puts it simply: "more than ⅛ of an inch, it's probably rotted." Decks.com uses the same 1/8 inch line and says it is likely time to consider replacement.
At the ledger, JLC's guidance is more specific. If the ledger has no flashing, probe it with an ice pick or screwdriver. Penetration of about 1/4 to 1/2 inch, or soft spongy wood, suggests the ledger needs replacing.
Probe the ledger, post bases, joist ends, the bottoms of stair stringers and any board that feels soft. Rot needs moisture, so the wettest, shadiest corners are where it starts. On doubtful spots, use Decks.com's pick test: if the wood bends slowly and doesn't splinter much when it breaks, that signals decay.
Ledger and lateral connections: the checks that matter most
The ledger is where NADRA says most collapses start, so check what holds it to the house and whether water can get behind it. NADRA's estimate is that 90 percent of collapses come from ledger connection failures.
One caveat. JLC's piece "We Don't Know What Causes Most Deck Collapses" points out that federal injury records come from ER notes, not inspectors, and no national system tracks why decks fail. When news reports name a cause, it is usually a ledger held on with nails only. So 90 percent is an industry estimate, not a measured statistic, but the ledger is still the first thing to check.
What to look for at the ledger:
- Fasteners. Through-bolts or structural lag screws spread along the ledger. Nail heads alone mean NADRA's "inspect immediately" rule applies.
- Flashing. A metal or membrane cap over the ledger that sheds water. NADRA's evaluation form checks for it.
- What it's attached to. DCA 6 prohibits ledgers on brick, stone or masonry veneer, hollow masonry, cantilevered floors and bay windows. It also prohibits lead anchors.
Lateral connections are the second half of this check. Simpson's homeowner sheet describes three forces on a deck (gravity, lateral and uplift) and the need for a continuous load path with metal connectors.
The American Wood Council's DCA 6 guide, which is based on the 2015 IRC, calls for the deck to be positively anchored to the house with hold-down tension devices in at least two places, each within 2 feet of the deck's ends and rated at 1,500 lb or more. If you can't find them, that is one more reason to have the ledger looked at.
The guard wobble test and stair check
Push hard on each guard post at the top; if it shifts more than an inch or two, JLC's deck-builder source says to replace it. Do the same along the top rail between posts, and push on the balusters. Fine Homebuilding's advice is to push firmly on each part of the railing.
These are the reference points current guidance uses. An older deck may not meet all of them, but they show what a builder would check.
| Item | Reference point | Source |
|---|---|---|
| When a guard is required | Walking surface more than 30 in above grade | 2021 IRC (Jaspector summary); DCA 6 |
| Guard height | At least 36 in (NADRA's form says ideally 42 in) | 2021 IRC; NADRA form via Pro Builder |
| Guard strength | Hold a 200 lb point load pushed outward and downward | 2021 IRC (JLC, Glenn Mathewson) |
| Guard post hold-downs | At least 1,800 lb tension for a 36 in guard; posts at least 4x4 | DCA 6 (2015 IRC basis) |
| Baluster spacing | Under 4 in on the deck; under 4⅜ in on stairs | NADRA form via Pro Builder |
| Stair triangle (under the rail) | Under 6 in | NADRA form via Pro Builder |
| Stair handrail | Required with 4 or more risers; 34 to 38 in above the nosings | DCA 6 |
| Stair width and stringers | At least 36 in wide; stringers at least 2x12 | DCA 6 |
For railing types and current code in more detail, see our deck railing guide.
For stairs, stand on each tread and rock side to side. Simpson's list of critical connections on existing decks includes the stair stringer to framing and each tread to its stringer.
How many decks collapse? What the injury data says
CPSC data counted about 8,700 injuries and two deaths from deck, porch and balcony collapses from 2020 to 2024, according to Consumer Reports' reading of CPSC data. Simpson Strong-Tie repeats the same figure. All the numbers below are national. No source publishes deck collapse data for Texas or Dallas.
| Source | Years | What it counted | Figure |
|---|---|---|---|
| Consumer Reports, citing CPSC | 2020 to 2024 | Collapses and floors giving way on decks, porches and balconies | About 8,700 injuries, 2 deaths |
| Legacy Services study of CPSC ER data | 2003 to 2007 | All injuries on wood decks and porches | 224,740 injuries |
| Legacy Services (same study) | 2003 to 2007 | Injuries from structural failure or collapse | 33,270 (nearly 15%): deck and porch 20,200, railing 11,120, stairs 1,950 |
| Legacy Services (same study) | 2003 to 2007 | Serious injuries from those failures | More than 18,000 |
| Fine Homebuilding, citing NADRA | 2000 to 2008 | Deaths from deck collapses | At least 30 |
| NADRA | 2023 | Decks in the US | 60 million+ (about 30 million past their useful life) |
These figures come from different studies with different methods, so don't add them together.
The older Legacy Services study splits injuries by deck part, but note its method: it left out wet or icy slips, splinters and alcohol, scaled 100 sampled hospitals up with a straight-line multiplier of 40, and found failures by searching ER notes for words like "collapse" and "gave way."
The research does show many decks are weaker than people assume. WSU structural engineer Don Bender called the deck "the most dangerous part of the house," and found that "many decks collapse before they reach their code-required design load."
Texas factors: clay soil, termites and the sun
Dallas decks fail in their own way: clay that swells and shrinks under footings, heavy termite pressure where wood meets soil, and 100°F sun that checks and splinters boards. Each one speeds up a warning sign above.
Blackland clay and footings
Much of the Dallas area sits on Blackland Prairie clay. The Soil Science Society of America places Houston Black clay, the Texas state soil, along the I-35 corridor from north of Dallas down to San Antonio, covering about 1.5 million acres. The clay swells in wet weather and shrinks in dry weather, opening cracks more than 4 inches wide and 12 inches deep that stay open 90 to 150 days in most years. The SSSA notes construction on it is often plagued by cracking, and that "erosion and water problems are the primary concerns."
For a deck, that means footings can lift and drop with the seasons. Check footings after a long dry spell and again after heavy rain.
Termites
Texas A&M rates termite entry risk as high anywhere wood is in contact with soil, and notes Texas has both native subterranean and Formosan termites. Posts set in the dirt and stringers on the ground are the spots to check. Texas A&M also notes termites can get moisture from leaky plumbing, roofs and gutters or air conditioning condensers.
Heat and UV
The National Weather Service says DFW summers are consistently in the 90s and often reach or exceed 100 degrees, with Gulf humidity and severe storms, including large hail and damaging winds, nearly every year. Block Renovation's Dallas guide says UV is intense from May to September and that composite handles UV better than wood.
If you're weighing materials that hold up in Texas, see our Texas deck materials guide and our page on composite decks in Dallas.
How often should a deck be inspected?
Do your own walk-around every spring; for a pro, the sources range from yearly (NADRA) to every five years once a deck is 10+ years old (Consumer Reports). The sources don't agree, so here is who says what.
| Source | Recommendation |
|---|---|
| NADRA (2024) | A licensed inspector should inspect the whole deck structure each year |
| Simpson Strong-Tie (2026) | Inspect the deck's critical connections at least once a year |
| Consumer Reports (2026) | Decks 10+ years old: at least every 5 years (yearly near the ocean) |
| Decks.com (2019) | Professional inspection for decks over 10 years old; guardrails about every 2 years |
A sensible reading: check it yourself every year, and get a professional once the deck passes about 10 years, after a high-seriousness sign, or before a home sale. Consumer Reports notes that on older homes the deck's attachment to the house isn't part of a standard home inspection, so a buyer's inspection may not cover the ledger in depth.
When to call a pro or a deck inspector (and what it costs)
Treat the deck as unsafe and get a professional to look at it if the ledger shows only nail heads, red rust won't wipe off the hardware, or the railing shifts more than an inch or two at the top. Those are the three cases where a source says to stop and act. Decks.com adds that even a slight sway warrants a professional inspection.
Who to call depends on what you found:
- A deck inspector. NADRA runs a Deck Inspection Certification Course, and you can find certified inspectors through its member directory.
- A structural engineer or contractor. Simpson's homeowner sheet says to consult one if you're unsure the deck is safe.
- A pest professional. For mud tubes or galleries in the wood.
What it costs, from the sources that publish a figure. These are national figures. No source publishes a Dallas-only deck inspection price.
| Source | What it covers | Price (national) |
|---|---|---|
| Consumer Reports (2026) | A qualified deck inspector | Typically $200 to $250 |
| Decks.com (2019) | Professional deck inspection | About $25 (30 minutes) to $199 (1 hour) |
The Decks.com figures are from 2019, so treat them as older.
What happens after you find a problem
Small surface problems (a popped nail, a splintered board) are maintenance; problems in the ledger, beams, hangers or footings mean a repair-or-replace decision. Fine Homebuilding's fixes for the surface are simple: tighten or replace loose fasteners, refasten loose boards with new screws, carve off or sand splinters and replace a board that is badly damaged.
Structural problems are a different decision. Simpson notes that rot in the frame can make the whole deck unstable, and Decks.com treats a screwdriver sinking past 1/8 inch as a sign it's time to consider replacement. For what each path costs, see deck repair vs replace in Dallas. Rebuilding structure may need a permit, which our Dallas deck permit guide explains.
When an old deck isn't worth saving, the answer is a new one built with bolted ledgers, metal connectors and proper footings from the start. Archetex Outdoor Design Co. designs and builds new composite and wood decks across Dallas and nearby cities, with a free site visit and a written price. See building a new deck in Dallas, and our Dallas deck cost guide for what a new deck runs.
