Most inspection failures are not exotic. They come from a short list of predictable causes: covering work before it was inspected, missing safety items like smoke alarms or required GFCI protection, sloppy connections and fastening, gaps in fireblocking or the garage separation, egress and guard issues, and building to a code number from the wrong edition. Almost none of that is bad luck. It is preventable if you know the categories inspectors flag most and you build to your jurisdiction's actual adopted code instead of a number you carried from another job. Here are the failure modes and how to pre-empt each one.
The number-one failure: you covered it before it was inspected
The single most common reason a job stalls has nothing to do with a dimension. It is procedural: you closed a wall, backfilled a trench, or poured a slab before the inspector could see the work. The inspector cannot approve what they cannot see, so you get told to open it back up, at your cost.
Pre-empt it by treating the inspection schedule as hard. Call the rough-in, pass it, then cover. No photo, no explanation, and no "I promise it's fine" substitutes for the inspector actually seeing it. This one is entirely in your control.
Building to the wrong edition's number
The failure that catches experienced tradespeople: you build to a code figure you know cold, and it fails, because your jurisdiction adopted a different edition or amended that provision. A stair dimension, a guard height, an egress size, a GFCI location, these get revised between editions, and some provisions even get renumbered.
Pre-empt it by confirming the adopted edition and amendments before you build anything dimensional, not after you fail. This is exactly why this reference routes numbers to your AHJ instead of printing them. Get the current figure for your jurisdiction from the Permit and Code Lookup tool.
Missing life-safety items
Inspectors are unforgiving on the things that kill people, and these are cheap to get right and expensive to miss:
- Smoke and carbon monoxide alarms. Placement, count, interconnection, and power source are all checked, and the required locations are specific. Missing or misplaced alarms fail a final fast.
- Electrical protection where it is required. Ground-fault and arc-fault protection are required in defined areas, and the required areas have expanded across recent code editions, so an older habit can leave you short. What counts as protected, and where, depends on your adopted NEC edition. The on-site electrical safety guide covers GFCI in the field; the code locations come from your adopted edition, so confirm them.
- Egress. Bedrooms and other spaces need a compliant emergency escape and rescue opening. Get the concept right, that these rooms need a way out, and confirm the exact sizing with your AHJ.
Fire separation and fireblocking gaps
The garage-to-house separation and fireblocking inside framing are classic framing-inspection fails, because they are easy to overlook and easy to see. The separation between a garage and living space, the protection where a habitable room sits over a garage, the self-closing door where required, and fireblocking at the concealed openings that would let fire spread, all get checked while the building is open. Miss one and the framing inspection stops. The materials and details are edition and amendment specific, so build to your adopted code.
Structural connections and fastening
A lot of framing fails are about how things are joined, not how big they are:
- Deck ledgers. A deck pulling away from a house is a killer, so the ledger attachment gets scrutiny. Nails alone as the sole attachment are out; positive mechanical fasteners in the right pattern are in. The exact fasteners and spacing come from your adopted edition.
- Framing connections, blocking, and bracing. Missing hangers, under-driven fasteners, missing blocking, and inadequate bracing are common flags.
- Anything undersized for its span or load. If it is outside the prescriptive tables, it needs an engineered design, and inspectors notice when a beam or joist is carrying more than the standard table allows.
Rough-in trade fails
Each trade has its recurring flags at rough-in:
- Electrical. Overstuffed boxes, unsupported cables, missing connectors and clamps, improper grounding and bonding, and neutrals landed wrong at a subpanel.
- Plumbing. Traps and vents done wrong, wrong slope on drain lines, missing cleanouts, and a water-heater temperature-and-pressure discharge that is trapped, valved, or terminated wrong.
- Mechanical. Unsupported or unsealed ductwork and combustion-air problems.
The principles are stable, the numbers, box volumes, trap-arm lengths, slopes, clearances, are edition specific. Confirm them with your adopted code.
The avoidable own-goals
Finally, the failures that are pure housekeeping:
- Permit not posted or plans not on site. The inspector shows up and cannot verify what was approved.
- Inspector could not access the work. Locked gate, dog in the yard, area blocked.
- Nobody on site. No one to answer questions or fix a minor item on the spot, so a small issue becomes a full re-inspection trip.
Post the permit, keep the approved plans on site, provide access, and have someone there. None of that costs anything.
Common questions
What is the most common reason a job fails inspection?
Covering work before it is inspected. Closing a wall, backfilling a trench, or pouring over rough-in before the inspector sees it is the top failure, because the inspector cannot approve work and will have you open it back up. It is also the most preventable, since it is entirely about scheduling, not skill. Call the required inspection, pass it, then cover. Treat the inspection schedule as a hard constraint on your build sequence, not a formality to fit in later.
Why did I fail for a code I have followed for years?
Most likely because your jurisdiction adopted a different code edition, or amended that provision, so the number you know is no longer the enforced number. Codes are revised every few years, requirements expand, and some sections get renumbered, so a figure you learned on an old job or in another county can quietly go out of date. Confirm the adopted edition and local amendments with your building department before you build anything dimensional, and get the current figure from the Permit and Code Lookup tool.
What do I do if I fail an inspection?
Get the correction notice in writing, fix every item it lists, and call for a re-inspection, do not argue on the spot or leave it hanging. The notice should cite what failed; if a reason is unclear, ask the inspector which code section applies so you know exactly what to correct. Address the whole list, not just part of it, then reschedule promptly. Handling a failed inspection and a stop-work order is covered in the guide on working with the building inspector.
Can I speed up passing inspection?
Yes, by getting the predictable things right before the inspector arrives: post the permit, keep the approved plans on site, provide clear access, have someone present who can answer questions, and do not cover any work first. Building to your jurisdiction's actual adopted code, not a remembered number, prevents the dimensional fails. Most re-inspection trips come from housekeeping and cover-ups, both of which are free to avoid. A clean, accessible, well-prepared site passes faster.
The honest bit
- This guide names the categories inspectors flag most and how to avoid them. It prints no dimensions, spacings, heights, or sizes, because what passes depends on your jurisdiction's adopted code edition and amendments. Get every figure from the Permit and Code Lookup tool and your building department.
- On-site electrical safety, including GFCI protection in the field, has its own guide. The code locations where protection is required depend on your adopted NEC edition, so confirm them locally.
- This is general guidance on common failure modes, not code interpretation. The inspector's reading of the adopted code is the one that counts on your job.
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