Exam Cheat Sheet · Quick Reference
ICC F29 Master Mechanical Exam (2015 IMC/IFGC)
National · Pearson Vue
Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.
Total questions
100
Passing score
70%
Exam time
240 min
Administered by
Pearson Vue
Format
Reference materials allowed
National State Portion 100 questions
General Requirements and Plan Reading
32 Q · 32%
Permit requirements and exemptionsConstruction document submission and approvalCode official authority and enforcementInspection types and procedures (underground, rough-in, final)Applicability to existing systems, alterations, and repairsKey IMC definitions and terminologyGeneral installation requirements for equipment and appliancesAccess and service space requirements for appliancesGeneral RegulationsScope and AdministrationDefinitions
Appliances and Equipment
12 Q · 12%
Installation requirements and listing standards for gas-fired heating appliances (wall furnaces, floor furnaces, duct furnaces, unit heaters, forced-air furnaces)Clearances to combustible materials for specific appliancesUnvented room heaters — prohibited locations, input limits, and oxygen-depletion safety shutoff requirementsClothes dryer exhaust systems — duct material, maximum length, termination, and transition duct requirementsBoiler installation — standards, clearances, safety/relief valves, low-water cutoffs, and gaugesDecorative appliances and gas fireplaces — flame safeguard devices, chimney damper free-opening area, and prohibited installationsCooking appliances — domestic vs. commercial distinctions, vertical clearance above cooking top, and prohibited locationsCooling towers, evaporative condensers, and pressure vessels — installation, safety relief devices, and ASME code complianceSpecific Appliances, Fireplaces and Solid Fuel-Burning EquipmentBoilers, Water Heaters and Pressure VesselsSpecific Appliances
Exhaust and Ventilation Systems
10 Q · 10%
Exhaust discharge location requirements and minimum separation distancesCommercial kitchen Type I and Type II hood systemsClothes dryer exhaust duct installation and maximum duct lengthHazardous exhaust systems for flammable vapors, dusts, and toxic materialsMakeup air requirements for exhaust systemsSmoke control system design and operationMechanical ventilation outdoor airflow rates by occupancy typeEnergy recovery ventilation system requirements and prohibited applicationsExhaust SystemsVentilation
Duct Systems
13 Q · 13%
Duct construction materials and minimum metal thickness requirementsDuct classification by operating pressureFlexible air ducts and flexible air connectors (length limits, installation, UL 181 compliance)Joints, seams, and connections sealing methods and standardsPlenum construction, materials, and flame/smoke index requirementsFire dampers, smoke dampers, and combination dampers (ratings, actuation, and required locations)Duct insulation, vapor retarders, and coverings requirementsReturn air opening restrictions and smoke detection system controls for air distribution systems
Combustion Air
8 Q · 8%
Indoor combustion air volume requirements (standard method and known air-infiltration-rate method)Outdoor combustion air openings: two-permanent-openings method sizing and placementOutdoor combustion air openings: one-permanent-opening method sizing and placementCombination indoor and outdoor combustion air sizing calculationsMechanical combustion air supply systems and appliance interlock requirementsLouvers, grilles, and screens: free area calculations and motorized louver interlock requirementsCombustion air duct construction, termination, and installation requirementsScope limitations: solid-fuel and oil-fired appliances, direct-vent appliances, and dampered openings under IMC Chapter 7
Chimneys and Vents
9 Q · 9%
Vent system types and applications (Type B, BW, L, single-wall metal pipe, special gas vent)Chimney and vent sizing methods for Category I appliances using tables and engineering methodsVent connector materials, construction requirements, and clearances to combustiblesChimney and vent termination locations and heightsDraft hoods, draft controls, and mechanical draft systemsFactory-built chimney listing, installation, and offset requirementsFlue lining systems for masonry chimneys (clay tile, listed liner systems)Appliances not required to be vented and unvented appliance aggregate input limitsChimneys and Vents
Fuel Supply Systems
9 Q · 9%
Gas pipe sizing methods and sizing tables (longest length, branch length, hybrid pressure)Allowable pressure drop and maximum design operating pressure limitsApproved piping materials and tubing types (steel, copper, CSST, polyethylene, aluminum)Piping joints, fittings, and connection methods for gas systemsPiping installation requirements (burial depth, prohibited locations, protection against damage and corrosion)Pressure testing, inspection, leak detection, and purging procedures for gas pipingShutoff valves, pressure regulators, and overpressure protection devicesFuel oil piping materials, joints, valves, fill/vent piping, and system testingGas Piping Installations
Special Requirements
4 Q · 4%
Refrigeration machinery room general and special requirements (Sections 1105–1106)Refrigerant classification, occupancy classification, and maximum allowable quantities (Table 1103.1)Refrigeration system classification and application requirements (high-probability vs. low-probability systems)Refrigerant piping materials, joints, location restrictions, and stop valve requirements (Section 1107)Refrigeration field pressure testing and certification requirements (Section 1108)Solar system special requirements: pressure/temperature relief, freeze protection, heat transfer fluid flash point, and roof-mounted collector construction (Sections 1402–1403)RefrigerationHydronic Piping
Electrical
1 Q · 1%
Electrical wiring, controls, and connections compliance with NFPA 70Label information requirements for electrical equipment and appliances (voltage, amperage, motor phase)Electrical receptacle outlet and luminaire requirements for appliances in attics and underfloor spacesElectrical receptacle outlet requirements for rooftop equipment locations
Water
2 Q · 2%
Hydronic piping material standards and ratings (Table 1202.4)Pipe fitting and valve material compatibility requirementsJoint types and installation methods by pipe materialShutoff valve placement requirements in hydronic systemsHydrostatic testing requirements for hydronic systemsEmbedded piping installation and pressure testing (radiant panels)Thermal barrier and insulation requirements for radiant floor systemsGround-source heat pump loop system piping, joints, and testing
Key Distinctions
Appliance in a private garagevsAppliance in a public garage / repair garage
IFGC 305.5 requires appliances in private garages to be a minimum of 6 feet above the floor (exception only where protected from vehicle impact and installed per the 18-inch ignition-source rule), while public garages require not less than 8 feet above the floor, and where vehicles can pass beneath, not less than 1 foot higher than the tallest vehicle garage door opening (e.g., 12-ft door = 13 ft).
IFGC 2015 Section 305.5Field bend in metallic gas pipevsField bend in plastic (polyethylene) gas pipe
Metallic pipe bends (IFGC 405.2) require an inside radius not less than six times the outside diameter and no arc greater than 90 degrees, while plastic pipe bends (IFGC 405.3) require the radius of the inner curve to be not less than 25 times the inside diameter with no joints in the bend.
IFGC 2015 Section 405.2Longest length method (IFGC 402.4.1)vsBranch length method (IFGC 402.4.2)
The longest length method sizes every section of the system from the single table row for the longest meter-to-outlet run (rounded up to the next longer row), while the branch length method sizes each branch from its own meter-to-outlet length and sizes the main sections from the longest run.
IFGC Section 402.4.1, Longest Length Method; Table 402.4(2), Schedule 40 Metallic Pipe (natural gas, 0.5 in. w.c. drop)Outdoor combustion air opening communicating directly with outdoors or through a vertical ductvsOutdoor combustion air opening through a horizontal duct
Under IFGC 304.6.1 the two-opening method requires 1 square inch per 4,000 Btu/h for direct or vertical-duct openings, but 1 square inch per 2,000 Btu/h where horizontal ducts are used.
IFGC 2015 Section 304.6.1Wood louvers of unknown free areavsMetal louvers and grilles of unknown free area
IFGC 304.10 says that where design and free area are not known, wood louvers are assumed to have 25-percent free area and metal louvers and grilles 75-percent free area.
IFGC 2015 Section 304.10Single-wall metal vent connectorvsType B double-wall vent connector
In a nonengineered Category I system (IFGC 503.10.8) the maximum horizontal length of a single-wall connector is 75 percent of the chimney or vent height (24-ft chimney = 18 ft), while a Type B double-wall connector is permitted 100 percent of that height (24 ft).
IFGC 2015 Section 503.10.8Unvented room heater in a bedroomvsUnvented room heater in a bathroom
IFGC 303.3 Item 4 permits a single wall-mounted unvented room heater in a bedroom with input not greater than 10,000 Btu/h (with oxygen depletion safety shutoff and room volume per 304.5), whereas Item 3's 6,000 Btu/h limit applies to bathrooms.
IFGC 2015 Section 303.3Plastic pipe carrying natural gasvsPlastic pipe carrying LP-gas
IFGC 404.17.1 limits plastic pipe to outdoor underground installation and caps operating pressure at 100 psig for natural gas, while the LP-gas limit in that same section is 30 psig.
IFGC 2015 Section 404.17.1Conflict between the mechanical code and a referenced standardvsConflict between code enforcement and the conditions of a listing
Under IMC 102.8.1 the provisions of the code apply when they conflict with a referenced standard, but where enforcement would violate the conditions of the listing, the IMC 102.8 exception directs that the listing and manufacturer's instructions apply (the 'most restrictive governs' rule of 102.1 applies only to conflicting sections within the code).
IMC 2015 Section 102.8.1Thimble 2 inches larger in diametervsThimble 4, 6 or 12 inches larger in diameter
IFGC 503.7.7 Item 1 normally requires a ventilated thimble 4 inches larger in diameter for listed draft-hood appliances and appliances listed for Type B vents, but permits only 2 inches larger where there is a run of not less than 6 feet of metal pipe in the open between the draft hood outlet and the thimble; 6 inches applies to unlisted draft-hood appliances and 12 inches to residential and low-heat appliances.
IFGC 2015 Section 503.7.7Furnace output rating (return air sizing)vsFurnace input rating
IFGC 618.2 sizes outdoor and return air ducts or openings at not less than 2 square inches per 1,000 Btu/h of furnace OUTPUT rating capacity (120,000 Btu/h output = 240 in²); using the input rating is a common error.
IFGC 2015 Section 618.2Equipment supported on a slab at gradevsEquipment suspended above grade
IMC 304.10 requires equipment installed at grade to be on a level slab or other approved material extending not less than 3 inches above adjoining grade, or alternatively suspended not less than 6 inches above adjoining grade.
IMC 2015 Section 304.10Bored holes in wood studs, generalvsBored holes in studs of nonbearing partitions
IFGC 302.3.4 limits bored holes for gas piping to 40 percent of stud depth generally but permits up to 60 percent in nonbearing partitions (the 25-percent figure in 302.3.3 is the notching limit for exterior walls and bearing partitions).
IFGC 2015 Section 302.3.4Key Terms
Dwelling (IMC 202) IMC 2015 Section 202 (Dwelling)
A building or portion thereof that contains not more than two dwelling units, a dwelling unit being a single unit providing complete independent living facilities.
IMC scope exception for dwellings/townhouses (IMC 101.2) IMC 2015 Section 101.2
Detached one- and two-family dwellings and multiple single-family dwellings (townhouses) not more than three stories high with separate means of egress, and their accessory structures, comply with the International Residential Code rather than the IMC.
Refrigerated room or space (IMC 202) IMC 2015 Section 202 (Refrigerated Room or Space)
A room or space in which an evaporator or brine coil is located for the purpose of reducing or controlling the temperature within the space to below 68°F (20°C).
Noncombustible materials (IMC 202; 308.3) IMC 2015 Section 202 (Noncombustible Materials); Section 308.3
Materials qualified by testing in accordance with ASTM E 136, including the criterion of no flaming from the specimen after the first 30 seconds; reduced-clearance protective assemblies, including structural and support elements and spacers, must be of such materials.
Flammability Class 2 refrigerant (IMC 202) IMC 2015 Section 202 (Flammability Classification)
A refrigerant with a lower flammability limit of more than 0.00625 lb/ft³ at 140°F and 14.7 psia and a heat of combustion of less than 8,169 Btu/lb (19 000 kJ/kg); Class 3 has an LFL at or below 0.00625 lb/ft³ or a heat of combustion of 8,169 Btu/lb or greater.
Board of appeals mechanical contractor member (IMC 109.2.1, Item 3) IMC 2015 Section 109.2.1
A mechanical contractor may fill the mechanical/plumbing seat with not less than 10 years' experience, 5 of which were in responsible charge of work.
Appliance shutoff valve at a manifold (IFGC 409.5.3) IFGC 2015 Section 409.5.3
An appliance shutoff valve may be installed at a manifold located within 50 feet of the appliance served where it is readily accessible and permanently identified, and the piping from the manifold to within 6 feet of the appliance is designed, sized and installed per Sections 401 through 408.
Double block and bleed valve system (IFGC 406.1.4) IFGC 2015 Section 406.1.4
The only condition under which a valve in a line may serve as a bulkhead between fuel gas in one section and the test medium in an adjacent section during section testing.
CSST bonding jumper (IFGC 310.1.1.3) IFGC 2015 Section 310.1.1.3
The bonding jumper between the connection to the gas piping system and the connection to the grounding electrode system shall not exceed 75 feet (22 860 mm) in length.
Tracer wire for nonmetallic underground piping (IFGC 404.17.3) IFGC 2015 Section 404.17.3
A yellow insulated copper tracer wire or other approved conductor not less than 18 AWG with insulation suitable for direct burial, installed adjacent to the piping with access or above-ground termination at each end.
Overpressure protection (IFGC 416.1, 416.2.1) IFGC 2015 Sections 416.1 and 416.2.1
Required where gas is delivered at greater than 2 psi to systems serving appliances designed for 14 inches w.c. or less; each device must be adjusted to limit pressure at each connected appliance to 2 psi or less upon failure of the line pressure regulator.
Exposed gas piping identification (IFGC 401.5) IFGC 2015 Section 401.5
For other than steel pipe, exposed piping is identified by a yellow label marked 'Gas' in black letters at intervals not exceeding 5 feet; marking is not required on pipe in the same room as the appliance served.
Shield plates for concealed piping/CSST (IFGC 404.7.1, 404.7.3) IFGC 2015 Sections 404.7.1 and 404.7.3
Steel plates not less than 0.0575 inch (No. 16 gage) thick extending not less than 4 inches to each side of the framing member, required where bored holes are less than 1 1/2 inches from the stud face.
Field drilling and tapping of pipe fittings (IFGC 403.10.4, Item 9) IFGC 2015 Section 403.10.4
Permitted only on systems operating at 5 psi or less, performed by the gas supplier or its designated representative per the supplier's written procedures, with the fitting outdoors and the assembly proven free of leakage.
Outdoor purging discharge point (IFGC 406.7.1.3) IFGC 2015 Section 406.7.1.3
The point of discharge must be not less than 10 feet from sources of ignition, not less than 10 feet from building openings, and not less than 25 feet from mechanical air intake openings.
Indoor piping over 5 psig (IFGC 402.6) IFGC 2015 Section 402.6
Indoor design operating pressure is capped at 5 psig except under listed conditions, which include piping in buildings or separate areas used exclusively for industrial processing or heating, research, warehousing, or boiler or mechanical rooms (retail, assembly and patient sleeping areas are not listed).
Attic passageway to an appliance (IFGC 306.3) IFGC 2015 Section 306.3
Generally limited to 20 feet measured along the centerline, but Exception 2 permits up to 50 feet where the passageway is not less than 6 feet high for its entire length (the unlimited-length allowance is for under-floor spaces, Section 306.4 Exception 2).
Underfloor space appliance lighting and power (IMC 306.4.1) IMC 2015 Section 306.4.1
A luminaire controlled by a switch located at the required passageway opening, and a receptacle outlet at or near the appliance location, in accordance with NFPA 70.
Alternative area method for chimney venting of two draft-hood appliances (IFGC 503.5.5, Item 3) IFGC 2015 Section 503.5.5
The effective chimney flue area shall be not less than the area of the larger draft hood outlet plus 50 percent of the smaller draft hood outlet area, and not greater than seven times the smallest draft hood outlet area.
Gas vent roof-slope termination (IFGC 503.6.4, Item 1) IFGC 2015 Section 503.6.4
Gas vents 12 inches or less in size located not less than 8 feet from a vertical wall or similar obstruction may terminate per Figure 503.6.4; larger vents or those closer than 8 feet must terminate 2 feet above the roof penetration and 2 feet above any portion of a building within 10 feet horizontally.
Domestic clothes dryer exhaust duct length (IMC 504.8.4.1) IMC 2015 Section 504.8.4.1
Maximum 35 feet from the connection to the transition duct at the dryer to the outlet terminal, reduced for fittings per Table 504.8.4.1; an identifying label is required where equivalent length exceeds 35 feet (Section 504.8.5).
Grease duct joints and thickness (IMC 506.3.1.1, 506.3.2.1) IMC 2015 Section 506.3.1.1
Type I grease ducts shall be steel not less than 0.0575 inch (No. 16 gage) or stainless steel not less than 0.0450 inch (No. 18 gage); permitted joints include butt joints, welded flange joints with maximum 1/2-inch flange depth, and telescoping/bell joints whose overlap shall not exceed 2 inches with inside cross-sectional difference not exceeding 1/4 inch.
Type I hood exhaust fan sensor activation (IMC 507.1.1) IMC 2015 Section 507.1.1
Where temperature or radiant energy sensors activate the fan, the fan shall activate not more than 15 minutes after the first appliance served by that hood is turned on.
Mechanical ventilation trigger for dwelling units (IMC 401.2) IMC 2015 Section 401.2
Where the measured air infiltration rate is less than 5 air changes per hour with a blower door at 0.2 inch water column, the dwelling unit shall be ventilated by mechanical means per Section 403.
Ground-source heat pump loop flow/pressure test (IMC 1210.10) IMC 2015 Section 1210.10
Actual flow rates and pressure drops are compared to calculated design values; where they differ by more than 10 percent the cause shall be identified and corrective action taken.
Formulas to Know
Gas piping test pressure and mechanical gauge range
Test pressure = not less than 1.5 × proposed maximum working pressure, but not less than 3 psig (2 psig MAWP → 3 psig). Mechanical gauge full-scale high end not greater than 5 × test pressure (5 × 3 psig = 15 psig). Duration: 1/2 hour per 500 ft³, but not less than 10 minutes for systems under 10 ft³ or in a single-family dwelling.Indoor combustion air, standard method minimum room volume
Volume = 50 ft³ per 1,000 Btu/h of total input of all appliances in the space (80,000 + 40,000 = 120,000 Btu/h ÷ 1,000 × 50 = 6,000 ft³).Outdoor combustion air, two-permanent-openings method
Each opening = 1 in² free area per 4,000 Btu/h of total input where it communicates directly with outdoors or through a vertical duct (120,000 ÷ 4,000 = 30 in² each); 1 in² per 2,000 Btu/h where horizontal ducts are used.Indoor combustion air from an adjoining room, two openings
Each opening = 1 in² free area per 1,000 Btu/h of total input, but not less than 100 in² (80,000 Btu/h → 80 in² calculated, so the 100 in² minimum governs).Furnace return/outdoor air duct or opening area
Area = 2 in² unobstructed per 1,000 Btu/h of furnace OUTPUT rating capacity (120,000 output ÷ 1,000 × 2 = 240 in²).Room volume to allow return air from a room containing fuel-burning appliances
Volume must exceed 1 ft³ per 10 Btu/h of combined input of all fuel-burning appliances in the room (75,000 + 40,000 = 115,000 ÷ 10 = 11,500 ft³), with supply air roughly equaling return air and inlets more than 10 ft from any draft hood.Unvented room heater input limits
Aggregate unvented appliance input ≤ 20 Btu/h per ft³ of room volume plus permanently open adjoining space (16 × 14 × 8 = 1,792 + 600 = 2,392 ft³ × 20 = 47,840 Btu/h), but any single unvented room heater is capped at 40,000 Btu/h input, which governs.Ventilation air for unvented infrared radiant heaters
Outdoor ventilation air = not less than 4 cfm per 1,000 Btu/h of aggregate input of all such heaters (300,000 ÷ 1,000 × 4 = 1,200 cfm).Gas demand conversion for pipe sizing tables (1,000 Btu/ft³ natural gas)
cfh = appliance input Btu/h ÷ 1,000; add the loads of all outlets served by a section (e.g., 120,000 + 40,000 + 150,000 = 310,000 Btuh = 310 cfh), then read the table row for the governing length and pick the smallest pipe whose capacity equals or exceeds the demand.Fire damper actuation temperature (not in a smoke control system)
Approximately normal duct operating temperature + 50°F, but not less than 160°F (100°F + 50°F = 150°F, so 160°F governs); the 350°F maximum applies only in smoke control systems.