How to Fail Your Municipality's Residential Final Mechanical Inspection.

Municipal residential building inspectors conduct final mechanical inspections to ensure all installed equipment and systems meet the requirements set by the International Residential Code (IRC). Inspections focus on the proper installation, operation, and accessibility of equipment, condensate drainage, gas appliance safety, dryer duct marking, equipment protection, refrigerant access port security, kitchen exhaust hood compliance, cooking appliance certification, and whole house ventilation.

Common Reasons for Inspection Failure:

1. Equipment Installation Complete/Operable [IRC 1307]: (Requirement)
   • Incomplete or inoperative installations.
   • Incorrect equipment installation.
   • Inspection Example: A furnace was installed but found non-operational during inspection.
2. Access to Equipment [IRC 1305.1]: (Requirement)
   • Inadequate or restricted access to mechanical equipment.
   • Inspection Example: The water heater was placed in a confined space, making it difficult to access for maintenance.
3. Condensate Drainage [IRC M1411.3]: (Requirement)
   • Improper drainage setup leading to potential water damage.
   • Missing or incorrectly installed condensate drain lines.
   • Inspection Example: The air conditioning unit’s condensate line was not properly sloped, leading to potential water pooling.
4. Gas Appliance Shut Off Valves [IRC G2420.5]: (Requirement)
   • Lack of accessible shut off valves for gas appliances.
   • Improper valve installation.
   • Inspection Example: A gas stove lacked a shut off valve, making it impossible to quickly stop gas flow in an emergency.
5. Gas Appliance Protection/Elevation [IRC G2406 &;; 2408]: (Requirement)
   • Gas appliances not elevated or protected as required, posing safety risks.
   • Inspection Example: A gas water heater installed in the garage was not elevated on a platform, posing a risk of flammable vapors igniting.
6. Dryer Duct Permanently Marked When Concealed and Greater Than 35ft [IRC M1502.4.5]: (Requirement)
   • Concealed dryer ducts over 35 feet not permanently marked, hindering future inspections or maintenance.
   • Inspection Example: The concealed dryer duct, running 40 feet, had no permanent marking for future reference.
7. Equipment Protection [IRC M1307.3.1]: (Requirement)
   • Lack of required protection for mechanical equipment, which could result in damage or safety hazards.
   • Inspection Example: The exterior HVAC unit lacked protective barriers, exposing it to potential impact damage.
8. Refrigerant Access Port Secured Protection [IRC M1411.6]: (Requirement)
   • Unsecured or unprotected refrigerant access ports, posing environmental and safety risks.
   • Inspection Example: The refrigerant port on the air conditioner was not secured with a tamper-resistant cap.
9. Kitchen Exhaust Hood 400 CFM and Greater Provided with Make Up Air [IRC M1503.4]: (Requirement)
   • Lack of make-up air for kitchen exhaust hoods with a capacity of 400 CFM or greater.
   • Inspection Example: The kitchen exhaust hood exceeded 400 CFM but lacked the required make-up air system.
10. Cooking Appliances Listed and Labeled for Household Use [IRC M1901.2]: (Requirement)
    • Non-compliant cooking appliances not listed or labeled for household use.
    • Inspection Example: A commercial-grade oven was installed in the kitchen, which wasn’t listed for residential use.
11. Whole House Ventilation Requirements [IRC 303.4]: (Requirement)
    • Failure to meet whole house ventilation requirements, especially if blower door tests indicate less than 5 ACH (air changes per hour).
    • Inspection Example: The house failed to meet ventilation standards after blower door testing showed less than 5 ACH, and no whole house ventilation system was installed.
12. Equipment Installation Complete/Operable [IMC 304]: (Requirement)
    • The equipment installation was not completed or was inoperable during inspection. Per IMC 304, all mechanical equipment must be fully installed, functional, and safe for operation.
    • Inspection Example: An air handler was installed but could not be powered on during the inspection.
13. Access to Equipment [IMC 306]: (Requirement)
    • The installed equipment was not readily accessible for inspection, service, repair, or replacement. IMC 306 requires safe and unobstructed access to all mechanical equipment.
    • Inspection Example: A furnace was installed in an attic space with no safe access point.
14. Condensate Drain [IMC 307]: (Requirement)
    • The condensate drain line was improperly installed, causing potential overflow or water damage. IMC 307 mandates proper installation of condensate drainage systems to prevent leaks and ensure efficient drainage.
    • Inspection Example: The condensate drain line for a heat pump was improperly routed, causing potential overflow issues.
15. Range Hood Venting [IMC 505]: (Requirement)
    • The range hood venting was not correctly routed to the outside, which can cause improper ventilation and air quality issues. IMC 505 specifies that range hoods must vent directly to the outdoors.
    • Inspection Example: The range hood venting was incorrectly routed into the attic instead of outside.
16. Programmable Thermostat [IECC 403.1.1]: (Requirement)
    • A non-programmable thermostat was installed, failing to meet the energy efficiency requirements. IECC 403.1.1 requires that programmable thermostats be installed to enhance energy efficiency and reduce energy consumption.
    • Inspection Example: A non-programmable thermostat was installed, failing to meet energy efficiency requirements.
17. Energy Certification Placed in Breaker Panel [IRC 1101.16]: (Design Criterion)
    • The required energy certification was missing from the breaker panel, leading to non-compliance with documentation standards. IRC 1101.16 mandates that an energy efficiency certification be placed in or near the main electrical panel. This only applies to design criteria requirements.
    • Inspection Example: The energy certification was missing from the breaker panel, causing a documentation failure.
18. Duct Leakage Test—Post-Construction [IECC 403.2.2]: (Design Criterion)
    • The ductwork failed the post-construction leakage test, exceeding the allowable air leakage limits. IECC 403.2.2 requires that ducts be tested for leakage after installation to ensure efficient and effective operation. This only applies to design criteria requirements.
    • Inspection Example: The ductwork failed the post-construction leakage test, exceeding allowable air leakage limits.
19. Attic access size [IRC Section M1305.1.3]: (Requirement)
    • When serviceable equipment is located in the attic, the attic access opening must be large enough to allow for the removal of the largest appliance:
      Specifically, the access opening must be at least 30 inches high and 22 inches wide.
    • Inspection Example: The attic access opening was only 24 inches high and 20 inches wide. This failed the inspection because it didn't meet the IRC M1305.1.3 minimum size of 30 inches high and 22 inches wide for serviceable equipment.
20. Auxiliary condensate or safety switch [IRC Section M1411.3.1]: (Requirement)
    • The requirement for an auxiliary condensate or safety switch is covered under IRC Section M1411.3.1. This section mandates the installation of a secondary drain or auxiliary drain pan for cooling or evaporator coils to prevent damage from overflow or stoppage in the condensate drain piping.
    • Inspection Example: The inspection revealed that an air handler was installed without an auxiliary condensate or safety switch. This lack of a backup system for overflow protection resulted in a failed inspection, as it did not comply with IRC M1411.3.1, which requires a secondary drain or auxiliary drain pan to prevent potential water damage.
21. Combustible clearance [IRC Section R1001.11]: (Requirement)
    • IRC Section R1001.11 specifies the minimum clearance distances required between combustible materials and masonry fireplaces to prevent fire hazards.
    • Inspection Example: During the inspection, the inspector found that the wood mantel was installed only 4 inches above the fireplace opening. This failed the inspection because it did not comply with IRC R1001.11, which requires a minimum clearance of 6 inches to prevent potential fire hazards.
22. Combustion Air provided [IRC Section M1701]: (Requirement)
    • Specifies that solid fuel-burning appliances must be provided with combustion air in accordance with the appliance manufacturer’s installation instructions, and oil-fired appliances must comply with NFPA 31.
    • Inspection Example: During the inspection, it was found that a gas furnace was installed in a sealed utility room with no dedicated combustion air openings. This failed the inspection because it did not meet IRC Section M1701, which requires adequate combustion air to ensure the safe and efficient operation of the appliance.
23. Condensate lines terminated property [IRC Section M1411.3]: (Requirement)
    • This section specifies that condensate from cooling coils and evaporators must be conveyed to an approved place of disposal, maintaining a minimum horizontal slope of 1/8 unit vertical in 12 units horizontal (1-percent slope).
    • Inspection Example: During the inspection, it was found that the condensate line from the air conditioning unit terminated directly into a floor drain without an indirect connection, violating IRC Section M1411.3. This improper termination could lead to potential backflow issues and was marked as a failure.
24. Drain pan 1.5in [IRC Section M1411.3.1]: (Requirement)
    • This section specifies that an auxiliary drain pan must have a minimum depth of 1.5 inches to prevent water damage in case of overflow or blockage in the primary condensate drain line.
    • Inspection Example: During the inspection, it was found that the auxiliary drain pan installed under the air conditioning unit was only 1 inch deep. This failed the inspection because it did not meet the IRC M1411.3.1 requirement of a minimum depth of 1.5 inches, which is necessary to adequately catch and redirect condensate water.
25. Dryer vented [IRC Section M1502]: (Requirement)
    • Specifies that dryer exhaust systems must be independent, convey moisture to the outdoors, and comply with the manufacturer’s installation instructions.
    • Inspection Example: During the inspection, it was found that the dryer vent terminated inside the attic instead of outside, violating IRC Section M1502. This improper termination could lead to moisture buildup and potential fire hazards, resulting in a failed inspection.
26. Exhaust vents to exterior [IRC Section M1504.3]: (Requirement)
    • This section specifies that exhaust air from mechanical systems must be discharged to the outdoors and not into attics, soffits, ridge vents, or crawl spaces.
    • Inspection Example: During the inspection, it was found that the bathroom exhaust vent terminated into the attic space instead of the exterior. This failed the inspection because it did not comply with IRC Section M1504.3, which requires exhaust air to be discharged to the outdoors to prevent moisture buildup and potential mold issues.
27. Flue vent/chimney terminated property [IRC Section M1801.3.2]: (Requirement)
    • This section specifies that the flue gas passageway must be free of obstructions and combustible deposits, and cleaned if previously used for venting a solid or liquid fuel-burning appliance or fireplace.
    • Inspection Example: During the inspection, it was found that the chimney flue was obstructed by a bird's nest and had significant creosote buildup. This failed the inspection because it did not comply with IRC Section M1801.3.2, which requires the flue gas passageway to be clear of obstructions and combustible deposits to ensure proper venting and prevent fire hazards.
28. Gas appliance vent [IRC Section M1801.1]: (Requirement)
    • This section specifies that fuel-burning appliances must be vented to the outdoors in accordance with their listing, labeling, and the manufacturer’s installation instructions, except for appliances listed and labeled for unvented use.
    • Inspection Example: During the inspection, it was found that a gas water heater was vented into the attic instead of being vented to the exterior as required. This failed the inspection because it did not comply with IRC Section M1801.1, which mandates that gas appliances must be properly vented to the outdoors to ensure safe operation and prevent potential hazards.
29. HVAC Functioning [IRC Section M1401.1]: (Requirement)
    • This section specifies that heating and cooling equipment and appliances must be installed in accordance with the manufacturer’s instructions and the requirements of this code.
    • Inspection Example: During the inspection, it was found that the HVAC system was not operational because the thermostat was not connected properly. This failed the inspection because it did not comply with IRC Section M1401.1, which requires that HVAC systems be fully functional and installed according to the manufacturer’s instructions.
30. No duct openings in garage [IRC Section R302.5.2]: (Requirement)
    • This section specifies that ducts in the garage and ducts penetrating the walls or ceilings separating the garage from the dwelling must be constructed of a minimum No. 26 gauge (0.48 mm) sheet steel or other approved material and must not have openings into the garage.
    • Inspection Example: During the inspection, it was found that the HVAC ducts penetrated the wall separating the garage from the living space and had openings into the garage. This failed the inspection because it did not comply with IRC Section R302.5.2, which aims to prevent the spread of fire and fumes from the garage to the living space.
31. Range hood vented [IRC Section M1503.1]: (Requirement)
    • This section specifies that residential range hoods must vent to the outdoors to effectively expel smoke, grease, and cooking odors, maintaining the home's air quality.
    • Inspection Example: During the inspection, it was found that the range hood vented into the attic instead of the exterior. This failed the inspection because it did not comply with IRC Section M1503.1, which requires range hoods to vent to the outside to prevent the recirculation of contaminants within the home.
32. Walkway provided [IRC Section R302.5.1]: (Requirement)
    • This section specifies that a walkway must be provided for pedestrian travel from a building entrance or exit to a public way. The walkway must be at least 4 feet wide and have a durable walking surface.
    • Inspection Example: During the inspection, it was found that the walkway leading from the front door to the sidewalk was only 3 feet wide and made of loose gravel. This failed the inspection because it did not meet the IRC Section R302.5.1 requirement of a minimum 4-foot width and a durable walking surface, which is necessary to ensure safe and accessible pedestrian travel.
33. Working clearance [IRC Section E3405.2]: (Requirement)
    • This section specifies the minimum clearances required around electrical equipment to ensure safe operation and maintenance.
    • Inspection Example: During the inspection, it was found that an electrical panel was installed with only 24 inches of working space in front, instead of the required 30 inches. Additionally, there were storage items and debris within the working space. This failed the inspection because it did not comply with IRC Section E3405.2, which mandates a minimum of 30 inches of clear working space in front of the panel to allow safe access and operation.

These descriptions help pinpoint the exact issues that can lead to failures during a final mechanical inspection, highlighting the importance of adhering to the specified codes.

These common mistakes often lead to inspection failures, resulting in additional costs and delays for homeowners and contractors. To ensure a successful inspection, attention to detail and adherence to the IRC standards as well as local municipal ordinances and requirements are crucial.

Attention to detail and adherence to these common code requirements can prevent inspection failures, ensuring safety and compliance.