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Community Development Department

3600 Kirchoff Road
Rolling Meadows, Illinois 60008
(847) 506-6030 (847) 483-0365 Fax
Effective July 1, 2009 - Office Hours - 8 a.m. - 4 p.m. Monday - Friday

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Most Common Construction Errors

The inspectors were asked to summarize the most frequently found code-related mistakes made during construction or installation. This is their response.

Common Error Categories:
Plumbing | Structural/Building | Electrical | Mechanical


Water Heaters:
Loose electrical connections
Flexible gas connections used
Flexible water connections used

Drainage & Vent Piping:
90 degree bends on horizontal runs instead of 45 degrees
Undersized vent lines
Horizontal vent piping run longer than code allows
Lack of water or air pressure testing of pipes


Dishwasher not anchored to counter
Dishwasher drain not looped and anchored to top of counter
Dishwasher drain connected to garbage disposal


Footing not the proper width or depth
Soil does not meet minimum bearing capacity (black humus soil)
Footing does not have 2'x4' keyway
Missing reinforcing steel
Steel reinforcing not lapped at ends and corners
Steel reinforcing too close to forms (do not have 2' concrete cover)


Framing varies from approved job site copy
Improper joist hanger and/or improper fastening of joist hangers
Improper boring and/or notching of joists
Trimmer joist at openings not doubled
Improper fastening of floor sheathing
Damage to prefabricated floor trusses


Improper boring and/or notching of wall studs and plates
Fireblocking at chase, soffit and tub waste pipe
Improper fastening of exterior wall sheathing
Improper fastening of wall studs
Improper transfer of concentrated loads under headers and beams (cripples)
Firestopping of top and bottom plate penetrations not installed
Improper fastening of foundation anchor bolts to bottom plate

Improper boring and/or notching of rafters
Damaged pre-fabricated trusses
Sheathing not fastened properly
Asphalt shingle fastening not to manufacturer requirements

Improper height of guardrail and/or baluster opening
Handrail missing or improper height or gripping size
Improper clearance to handrail from adjacent wall
Handrail not continuous
Improper riser depth
Improper tread width
Improper tread dimension on winder stair
Handrail not continuous on winder stairs
Headroom not 6'x8"

Insulation & Ventilation:
Vapor retardant missing or reversed
R-30 vaulted rafters (no blow-in)
Baffles missing
Insulation not secured
Exposed paper backing on insulation in basement
Insulation missing at rim joist
Exterior side of walls or roof not sealed against the weather
Eave vents not installed
Ventilation blocked by insulation

ELECTRICALUnderground Conduit Depth:
EMT (thinwall) buried in the ground
Heavy wall not buried the required 6' below grade
PVC conduit not installed 18' below grade
Direct burial cable not installed 24' below grade


Conduit not strapped
Connectors and couplings not tightened

Rough Walls:

Boxes not fastened securely
Conduit not strapped 3' from any boxes

Rough Ceiling:

Boxes not fastened
IC type recessed fixture must be used if ceiling is insulated
Closet fixture light boxes not 18' minimum from the back wall of the closet

Electrical Service:

Service wire not clearing the roof by 18'
Service mast shall be secured with proper type screws or bolts (not drywall screws)
Service wires not 10' above grade
End of conduit for the ground conductor going to the ground rod not grounded
Bond bushing not installed on concentric knockout
Bond jumper on the neutral bar not installed
Jumper wire at the water meter and proper ground tag not installed
Ground rod at electric meter not driven 8' and below grade

Final inspection:
All electrical equipment not complete, hooked-up and working
Every fixture must have working bulbs
All devices shall be turned on for testing
Island or peninsular counter outlets shall be mounted not more than 6' below the counter top and shall not be mounted where the countertop extends more than 6' beyond its support base
Motor for the jetting tub not grounded with a #8 AWG wire back to the conduit system
Breaker for A/C compressor is larger than manufacturer's label indicates for maximum overcurrent protection

Wire Inspection (required):
Box fill is exceeded (check Table 370-16 of National Electrical Code)
Outlets and switches not grounded to the junction box with a green wire, if the device is not self-grounding type
MECHANICALDuct Installation:
Ductwork not fastened together at joints
Sealing tape not applied on joints
Ductwork not installed to plan
Bath fan not vented to the exterior
Kitchen hood vent not installed properly
Dryer vent ductwork over 25 ft. in length and reduced 5 feet for each 90 degree bend
Ductwork in crawl space not suspended at least 4 inches above earth
Ductwork in crawl space suspended more than 6' below the floor
Duct openings not protected (covered) during construction
Duct work in unconditioned space not insulated

Furnace Installation:
Furnace installed without proper clearances
Insufficient clearance between closet door and furnace
Clearance between B-vent and combustibles is less than 1 inch.
Clearance between single wall flue pipe and combustibles is less than 6 inches.
Single wall flue pipe cannot be run through ceilings or floors
Drain liens for furnace not installed
A/C unit coil not installed
B-Vent installed with more than 2 - 90 degree elbows

Furnaces Installed in Attic:
Incorrect working clearances (must be 22' wide and 30' high)
Work area in front of furnace must be 30' long and 30' high
Must have outlet and light in furnace area
Light must be switched at opening to attic
Attic access must allow removal of furnace's largest part
Drain pan under A/C coils with two (2) drain lines, one (1) to conspicuous place

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