Common Inspection Failures: Top 20 and How to Avoid Them

In all of the custom home builds, I've seen these failures repeatedly.

Learn from others' expensive mistakes and pass your inspections on the first try.

Top 20 Inspection Failures

1. Missing or Incorrect Joist Hangers

• What it is: Joist hangers missing, wrong size, or improperly nailed
• Why it fails: Structural connection critical for load transfer
• Code reference: IRC R502.6, R802.3

How I see it happen:

• Framers use wrong size hanger for joist dimension
• Not enough nails in hanger (each hole must have a nail)
• Using common nails instead of joist hanger nails
• Hangers upside down or sideways

How to avoid:

• Buy correct hangers for your joist size (2x8 joist = specific 2x8 hanger)
• Count nail holes - every one gets a nail
• Use only joist hanger nails (shorter, fatter shank)
• Install with flanges against joist, bottom supporting joist

Cost to fix: $200-500 (carpenter callback to replace hangers)

2. Improper Bearing for Beams

• What it is: Beams don't have adequate bearing on posts or walls
• Why it fails: Beam could slip off bearing surface under load
• Code reference: IRC R502.6 - minimum 1.5" bearing for sawn lumber, 3" for beams

How I see it happen:

• Beam sits on less than required bearing
• Beam overhangs post
• No positive connection between beam and post
• Bearing surface not properly sized

How to avoid:

• Measure actual bearing - don't eyeball it
• Ensure minimum 1.5" for sawn lumber, 3" for engineered beams
• Use post caps to positively connect beam to post
• Verify bearing surface is level and properly sized

Cost to fix: $300-800 (structural modifications)

3. Missing Fire Blocking

• What it is: Required fire blocking not installed in walls or floor/ceiling assemblies
• Why it fails: Fire code requirement to slow vertical fire spread
• Code reference: IRC R302.11

How I see it happen:

• Forgotten entirely
• Installed but missing in some bays
• Not properly fitted (gaps remain)

Where required:

• Walls: At 10' vertical intervals, at ceiling/floor levels
• Soffits
• Cove molding spaces
• Between first story and basement
• Furred spaces

How to avoid:

• Know where fire blocking is required before you frame
• Install as you frame (don't wait)
• Use solid blocking or two layers of 5/8" drywall

Cost to fix: $200-400 (cutting drywall to access, installing, repairing)

4. Incorrect Stair Dimensions

• What it is: Rise or run outside code requirements
• Why it fails: Safety - inconsistent stairs cause falls
• Code reference: IRC R311.7.5

How I see it happen:

• Last riser different height than others
• Treads not consistent depth
• Headroom calculated wrong
• Winders don't meet minimum at walking line

How to avoid:

• Calculate rise and run before building
• Verify total rise with actual floor-to-floor dimension
• Build stringers carefully
• Measure each riser and tread
• Check headroom at all points

Cost to fix: $800-2,000 (rebuild stairs)

5. Missing AFCI or GFCI Protection

• What it is: Required Arc Fault or Ground Fault protection not installed
• Why it fails: Electrical safety code requirement
• Code reference: NEC 210.12 (AFCI), 210.8 (GFCI)

How I see it happen:

• Using standard breakers instead of AFCI
• Missing GFCI outlets in required locations
• GFCI installed but not actually protecting downstream outlets

How to avoid:

• Use AFCI breakers for all required circuits
• Install GFCI outlets at first receptacle in bathroom/kitchen circuits
• Test GFCI protection works for all downstream outlets
• Label which GFCI protects which outlets

Cost to fix: $150-400 (breaker replacements, outlet replacements)

6. Improper Plumbing Venting

• What it is: Drain/waste/vent system doesn't meet code
• Why it fails: Prevents proper drainage, allows sewer gas entry
• Code reference: IRC P3104-P3111

How I see it happen:

• Fixtures not properly vented
• Vent pipe too small
• Horizontal vents not sloped properly
• Wet venting done incorrectly
• Vent termination too close to windows/doors

How to avoid:

• Hire a licensed plumber
• Verify each fixture is properly vented
• Check vent pipe sizing (usually 1.5" minimum)
• Ensure vent termination is 10' from windows/doors horizontally, 3' above roof

Cost to fix: $500-1,500 (cutting walls, re-piping)

7. Wrong Wire Size for Circuit

• What it is: Wire gauge doesn't match circuit breaker size
• Why it fails: Fire hazard - wire overheats
• Code reference: NEC 240.4

How I see it happen:

• 14 AWG wire on 20 amp breaker
• Mixing wire sizes on same circuit
• Using aluminum wire without proper techniques

How to avoid:

• Match wire size to breaker
• Never use 14 AWG on 20 amp breaker
• Mark circuits clearly
• Use professional electrician

Cost to fix: $200-1,000 (rewiring circuits)

8. Inadequate Egress Windows

• What it is: Bedroom windows don't meet egress requirements
• Why it fails: Life safety - need escape route in fire
• Code reference: IRC R310 (R310.2.1 for opening area) — verify your jurisdiction's adopted edition

How I see it happen:

• Windows too small
• Sill too high
• Window well doesn't meet requirements
• Bars on windows without quick-release

How to avoid:

• Specify egress windows before ordering
• Measure opening area (not window dimensions)
• Install with proper sill height
• Test that window fully opens

Cost to fix: $800-3,000 (new window, framing changes)

9. Missing Lateral Bracing on Beams

• What it is: Beams not properly braced to prevent rotation/buckling
• Why it fails: Structural stability requirement
• Code reference: IRC R502.8, R802.8

How I see it happen:

• Long-span beams with no mid-span bracing
• Truss heel blocking missing
• Ridge beam not properly supported

Where required:

• Beams over 4' span need lateral support
• Roof trusses need heel blocking
• Rafters need ridge beam support

How to avoid:

• Install solid blocking between joists at beam bearing points
• Add bracing at intervals per span tables
• Install heel blocking on trusses

Cost to fix: $200-500 (adding bracing)

10. Improper Notching of Structural Members

• What it is: Joists, rafters, or studs notched beyond code limits
• Why it fails: Reduces structural capacity
• Code reference: IRC R502.8 (floors), R602.6 (walls), R802.7 (roofs)

How I see it happen:

• Plumber cuts too-large notch for pipe
• Electrician drills oversized hole
• Notch in wrong location
• Multiple notches weakening member

How to avoid:

• Know the limits before cutting
• Route pipes and wires through proper locations
• Use hole size limits: max 1/3 depth, 2" from edge
• Never notch engineered lumber

Cost to fix: $300-1,000 (sistering members, structural repairs)

11. Electrical Boxes Not Flush

• What it is: Outlet/switch boxes recessed or protruding from wall surface
• Why it fails: Code requirement for proper device installation
• Code reference: NEC 314.20

How I see it happen:

• Drywall thickness not considered when mounting boxes
• Tile thickness not accounted for
• Boxes mounted too deep

How to avoid:

• Know finished wall thickness before mounting boxes
• Use box extenders if drywall is thicker than expected
• Check boxes for flush fit before drywall

Cost to fix: $100-300 (box extenders or remounting)

12. Missing Handrail or Guards

• What it is: Required handrails or guardrails not installed
• Why it fails: Fall protection safety requirement
• Code reference: IRC R311.7.8 (handrails), R312 (guards)

How I see it happen:

• Deck without guards
• Stairs without handrail
• Baluster spacing too wide
• Handrail at wrong height

How to avoid:

• Install handrails on all stairs with 4+ risers
• Install guards at all drops 30"+
• Test 4" sphere can't fit through balusters
• Measure handrail height at nosing

Cost to fix: $500-2,000 (building and installing rails)

13. Inadequate Ventilation

• What it is: Attic or crawl space ventilation insufficient
• Why it fails: Moisture control, energy code requirement
• Code reference: IRC R806 (attic), R408 (crawl space) — verify your jurisdiction's adopted edition

Requirements:

• Attic: 1/150 of attic floor area (or 1/300 with proper ventilation balance)
• Crawl space: 1/150 of crawl space floor area by default, but R408.2 allows reduction to 1/1,500 where the ground is covered with a Class I vapor-retarder material and openings provide cross ventilation
• Unvented/conditioned crawl spaces (R408.3) are also permitted with no vents, provided the exposed earth is covered with a continuous Class I vapor retarder and the space is conditioned or mechanically ventilated per that section

How I see it happen:

• Not enough roof vents
• Blocked soffit vents
• No vapor barrier in crawl space
• Insulation blocking ventilation

How to avoid:

• Calculate required ventilation area
• Install proper balance of soffit and ridge vents
• Don't block vents with insulation
• Use proper baffles

Cost to fix: $500-1,500 (adding vents)

14. Shower Pan Flood Test Failure

• What it is: Shower pan doesn't hold water during flood test
• Why it fails: Leak will damage structure
• Code reference: IRC P2709

Test requirements:

• Plug drain
• Fill pan to dam height
• Let sit 24 hours minimum
• No water loss allowed

How I see it happen:

• Pan liner punctured during installation
• Improper dam height
• Drain connection leaks
• Liner not properly lapped at seams

How to avoid:

• Protect liner during installation
• Test BEFORE tile
• Check all seams
• Ensure proper dam height (2" above finished curb)

Cost to fix: $500-3,000 (depends if tile is installed yet)

15. Tempered Glass Not Installed Where Required

• What it is: Regular glass used where safety glass required
• Why it fails: Life safety requirement
• Code reference: IRC R308.4

Where tempered glass required:

• Within 24" of door
• Glass in doors
• Glass less than 60" above tub/shower floor
• Glass less than 60" above walking surface and within 36" horizontally of walking surface

How I see it happen:

• Builder/owner doesn't know requirement
• Window supplier provides wrong glass
• Not verified at installation

How to avoid:

• Check all glazing locations against code
• Verify tempered glass before installation
• Look for tempered label in corner

Cost to fix: $400-2,000 (replacing glass)

16. Insulation Gaps and Voids

• What it is: Insulation not completely filling cavities
• Why it fails: Energy code requirement
• Code reference: IRC N1102 (energy code)

How I see it happen:

• Insulation compressed
• Gaps around outlets and penetrations
• Voids in corners
• Improperly cut batts

How to avoid:

• Fill all cavities completely
• Don't compress insulation
• Cut batts to fit around obstacles
• Install baffles at eaves
• Air seal before insulating

Cost to fix: $200-800 (adding insulation)

17. Drain Lines with Improper Slope

• What it is: Horizontal drain pipes don't slope correctly
• Why it fails: Won't drain properly
• Code reference: IRC P3005.3

Requirements:

• Minimum 1/4" per foot slope
• Maximum 3" per foot slope (rare to exceed)
• No sags or bellies

How I see it happen:

• Sagging pipes
• Insufficient slope
• Reverse slope

How to avoid:

• Support pipes properly
• Check slope with level
• Use laser level for long runs

Cost to fix: $300-1,000 (re-piping sections)

18. Smoke and CO Detectors Missing

• What it is: Required detectors not installed
• Why it fails: Life safety requirement
• Code reference: IRC R314, R315

Requirements:

• Smoke detector in each bedroom
• Smoke detector outside each sleeping area
• Smoke detector on each level including basement
• CO detector outside each sleeping area
• CO detector on each level

How I see it happen:

• Forgotten until final inspection
• Wrong locations
• Not interconnected

How to avoid:

• Wire for detectors during rough electrical
• Install before final inspection
• Interconnect per code (all alarms sound together)

Cost to fix: $200-500 (adding detector locations)

19. Wood-to-Concrete Contact

• What it is: Wood members in direct contact with concrete without protection
• Why it fails: Moisture will rot wood
• Code reference: IRC R317

Requirements:

• Pressure-treated wood, or
• 1" air gap, or
• Impermeable moisture barrier

How I see it happen:

• Bottom plate on slab with no sill gasket
• Sleepers on concrete without PT lumber
• Posts on concrete without barrier

How to avoid:

• Use pressure-treated (PT) lumber for all wood touching concrete
• Use sill gasket under bottom plates
• Ensure PT lumber is rated for ground contact if on grade

Cost to fix: $500-2,000 (replacing lumber)

20. Service Disconnect Missing

• What it is: No accessible disconnect for AC or heat pump
• Why it fails: Safety requirement for servicing
• Code reference: NEC 440.14

Requirements:

• Disconnect within sight of equipment, or
• Lockable disconnect at panel

How I see it happen:

• HVAC installer forgets disconnect
• Disconnect installed but not accessible
• Wrong type of disconnect

How to avoid:

• Install disconnect near exterior unit
• Ensure clear access
• Use proper disconnect type for equipment

Cost to fix: $150-400 (installing disconnect)

Patterns in Failures

Failed Because Work Wasn't Complete

Don't call for inspection until actually ready:

• All required work installed
• Area cleaned and accessible
• Testing complete (where required)

Failed Because Didn't Match Plans

Build what's on approved plans:

• If you change something, get plan amendment first
• Keep site plans current
• Document any approved field changes

Failed Because Contractor Didn't Know Code

This is on you to manage:

• Hire licensed contractors for critical work
• Verify they know current code
• Spot-check their work against code

Failed Because Inspector Was Having a Bad Day

Reality: This happens

• Usually still valid issue, just nitpicky
• Appeal if truly unreasonable
• Fix it and move on

Prevention Strategy

Before You Build

• Study IRC and local amendments
• Understand what will be inspected
• Review inspection guides for each trade
• Plan for inspections in your schedule

During Construction

• Build to code, not to "good enough"
• Check your own work before calling inspector
• Take photos before covering
• Ask contractors about code compliance

Before Inspection

• Walk through with checklist
• Verify everything is complete
• Clean and light work area
• Review what inspector will check

During Inspection

• Be present
• Take notes
• Ask questions
• Don't argue

Quick Reference Checklist

The Bottom Line

Every failed inspection is a lesson. Don't repeat the same mistake twice.

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**Detailed guides for each inspection type