ICC M2 cheat sheet

Permits are required for new installation, alteration, replacement, and relocation of mechanical systems; ordinary repairs not involving fuel or electrical connections are exempt.

A permit application must include construction documents showing the scope, equipment location, and clearances; work may not begin until the permit is issued.

Inspection stages typically include rough-in (before concealment) and final; concealed work must be inspected before covering.

Approved materials and appliances must be listed and labeled by a recognized agency; field modification of listed equipment voids the listing.

Materials must be installed per their listing and the manufacturer's installation instructions; instructions govern where the code is silent.

Defects found on inspection must be corrected and re-inspected; the authority may order the work stopped for noncompliance.

Existing installations that are unsafe or unsanitary may be ordered repaired, altered, or removed regardless of when installed.

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

Appliances installed in garages must have ignition sources elevated so burners and ignition are at least 18 in. above the floor unless the appliance is listed for lower installation.

Attic and under-floor furnaces need a level service platform, a passageway, and clearance to allow burner, control, and heat-exchanger service.

Clearances to combustible construction follow the listing label; reduced clearances require an approved method such as a listed clearance-reduction shield.

A furnace must not be installed in a closet unless the closet is dedicated and clearances and combustion/dilution air are provided.

Return-air openings must not draw from a bathroom, toilet room, kitchen, garage, or unconditioned attic unless specific code conditions are met.

Air-conditioning condensate drains require a trap, slope, and a secondary or auxiliary drain or pan with a drain for units in concealed spaces.

Appliances must be installed on a firm, level base; floor-mounted units need access for filter and blower service.

Duct systems must be substantially airtight; joints, seams, and connections are sealed per the duct-sealing class required by the code.

Ducts in unconditioned space require insulation with a vapor retarder on the warm side to limit condensation.

Return ducts in garages or unconditioned spaces must be sealed and separated to prevent drawing contaminants into the occupied space.

Minimum outdoor air ventilation rates for occupancies are set by the mechanical ventilation provisions based on occupancy and floor area.

Exhaust systems for bathrooms and kitchens must discharge outdoors and terminate with an approved hood or backdraft damper.

Duct penetrations of fire-rated assemblies require approved fire dampers installed per their listing.

Flexible duct length, sag, and support spacing are limited by the listing; supports are required at intervals and at bends.

The standard method for indoor combustion air uses two permanent openings: one within 12 in. of the top and one within 12 in. of the bottom of the enclosure.

For the two-opening method, each opening must have a free area of at least 1 sq in. per 1,000 Btu/h of total input, with a minimum of 100 sq in. per opening.

If openings connect to outdoor air through vertical ducts, each opening is 1 sq in. per 4,000 Btu/h; through horizontal ducts, 1 sq in. per 2,000 Btu/h.

A single permanent opening near the top may be used when it has free area of at least 1 sq in. per 3,000 Btu/h of total input.

A Category I appliance vents with a listed vent connector; vent connector slope is at least 1/4 in. per ft upward toward the chimney or vent.

Vent termination must be above the roof line per the vent listing and must be clear of windows, doors, and air intakes.

A chimney must be lined and of the correct size; an oversized flue can cause condensation and poor draft.

Type B vent requires listed clearances to combustibles; single-wall connectors require greater clearance unless shielded.

Refrigerant piping must be supported, protected from physical damage, and installed with approved fittings; brazing requires purging and proper procedures.

Refrigerant quantity limits for a space are based on the refrigerant's safety classification and the volume of the occupied space.

Hydronic systems require expansion control, air elimination, and pressure-relief protection; relief valves discharge to a safe location.

Boiler relief valves must not be plugged or reduced and must discharge by gravity to a safe place of disposal.

Fuel gas piping must be sized for the total connected load and tested for leaks before being placed in service.

Gas piping test pressure and duration depend on the system; the test medium is typically air or inert gas, not fuel gas.

Gas piping must be supported at intervals and protected where passing through walls, and sediment traps are required at appliance connections.

Oil piping and tanks require approved materials, protection from damage, and venting per the code.