ICC M3 cheat sheet

Permits are required for installation, alteration, replacement, or relocation of mechanical systems; ordinary repairs and routine maintenance do not require a permit.

Permit applications must include construction documents drawn to scale showing the size, location, and type of equipment, ductwork, and piping.

Inspection stages typically include rough-in inspection before concealment and final inspection after the system is complete and operational.

The code official may require tests to demonstrate compliance; work not approved must be corrected and reinspected before use.

Approved materials and appliances must be listed or labeled by an approved agency where the code requires listing.

Defective or noncompliant work may be ordered stopped by a stop-work order until the condition is corrected.

Appeals of code official decisions go to the board of appeals within the time specified by the adopting jurisdiction.

Equipment must be installed per the manufacturer's listed instructions; where instructions conflict with the code, the more restrictive applies.

Unsafe conditions constitute grounds for the code official to order the equipment or system disconnected from its energy source.

Return air from a dwelling unit must not be taken from a different dwelling unit, and return air plenums must not draw from bathrooms, kitchens, or closets.

Combustion appliances located in a garage must have ignition sources elevated not less than 18 inches above the floor unless listed for garage installation.

Appliances in attics and crawl spaces need a permanently installed walkway or service platform and a lighting outlet near the service access.

Working clearance in front of heating and cooling equipment is generally 30 inches wide by 30 inches deep, or the manufacturer's larger requirement.

A cooling coil condensate drain must be trapped and discharged to an approved receptor; a secondary drain or pan with a switch is required where damage could occur.

Outdoor condensing units require clearance per the manufacturer's instructions for airflow and service access.

Ventilation air quantities for occupancies are determined from the adopted mechanical code or referenced ventilation standard tables.

Equipment must be accessible for inspection, service, repair, and replacement without removing permanent construction.

Bathroom and toilet room exhaust must discharge outdoors, not into an attic, crawl space, or other interior space.

Domestic kitchen exhaust hoods must discharge outdoors except where listed recirculating systems are permitted by the code.

Clothes dryer exhaust ducts must terminate outdoors with a backdraft damper and must not use screws or fasteners that penetrate the duct interior.

Dryer exhaust duct length limits and equivalent lengths for fittings are set by the manufacturer and the code; transitions to smaller duct sizes are prohibited.

Type I commercial kitchen hoods require grease duct enclosure, clearance to combustibles, and a fire suppression system.

Type II hoods are for heat, moisture, and odors without grease or smoke and do not require grease duct protection.

Exhaust ducts from hazardous or noxious sources must not connect to other exhaust systems and must discharge to a location that protects building openings.

Makeup air must be provided for exhausted air in quantities sufficient to maintain the required pressure relationships and appliance draft.

Duct systems must be sized, installed, and sealed to convey air without leakage into or from the building envelope beyond code allowances.

Ducts in unconditioned spaces must be insulated to the required R-value and have a vapor retarder on the exterior of the insulation.

Factory-made flexible duct must be supported at intervals not exceeding 4 feet and not be compressed or bent sharply.

Duct penetrations of fire-rated assemblies require listed fire dampers installed per their listing and the assembly's rating.

Combustion air for fuel-burning appliances is provided by the indoor air method, outdoor air method, or a combination, per code volume and opening sizing rules.

Two permanent openings to outdoors are sized based on the total input rating of appliances in the space, using the code's ratio of free area to Btu/h input.

Where combustion air is taken from indoors, the space must meet the code's minimum volume per Btu/h of appliance input or be provided with outdoor air.

Duct joints, seams, and connections must be sealed with approved materials; tapes and mastics must be listed for the application.

Return air ducts must not pass through or connect spaces prohibited by the code, such as bathrooms, kitchens, or garages.

Chimney and vent connectors must be sized to the appliance input and installed with the required rise and slope toward the chimney.

Vent termination height above roofs is determined by roof pitch and proximity to walls, dormers, and air intakes.

Category I appliances vent under negative pressure and require a properly sized vertical vent or chimney; Category IV appliances are positive pressure and require listed venting.

A vent connector must not be smaller than the appliance flue collar and must slope upward toward the chimney at the code-required rate.

Mechanical draft systems must be listed and installed so that flue gases are safely vented under all operating conditions.

Refrigerant systems must use refrigerants classified by safety group, and refrigerant quantity limits per occupied space apply.

Refrigerant piping must be supported, protected from physical damage, and tested for leaks before being placed in service.

Machinery rooms for refrigeration systems require the ventilation, detection, and access provisions specified for the refrigerant class and charge.

Chimneys must be supported independently and provided with the required clearance to combustibles or listed clearance reduction methods.