South Carolina Residential Builder

Key Concepts

Footings & Foundations

• Minimum footing depth must extend below the frost line. In South Carolina, frost depth is generally shallow (6–12"), but IRC Table R301.2(1) requires footings to be placed at depths specified by the local jurisdiction to prevent frost heave.
• Footing width and thickness are determined by soil bearing capacity. Default assumed soil bearing capacity is 1,500 psf unless a geotechnical evaluation provides a different value (IRC R401.4).
• Minimum footing thickness: 6 inches for concrete footings; width must be at least as wide as the wall it supports and sized to distribute load within allowable soil bearing capacity.
• Concrete compressive strength (f'c) requirements by location:
• Basement walls, foundations not exposed to weather: 2,500 psi minimum
• Exterior exposed concrete (moderate weathering): 3,000 psi minimum
• Severe weathering exposure: 3,500 psi minimum (IRC Table R402.2)
• South Carolina is generally classified as a negligible to moderate weathering region.

Soil Bearing Capacity

• IRC Table R401.4.2 lists presumptive load-bearing values by soil type:
• Crystalline bedrock: 12,000 psf
• Sedimentary rock: 4,000 psf
• Sandy gravel/gravel: 3,000 psf
• Sand, silty sand, clayey sand: 2,000 psf
• Clay, sandy clay: 1,500 psf
• If soil conditions are questionable or loads are heavy, a geotechnical investigation (soil test/borings) is required per IRC R401.4.

Foundation Anchorage (Sill Plates)

• Anchor bolts: minimum ½-inch diameter, embedded 7 inches into concrete or masonry.
• Spacing: maximum 6 feet on center; within 12 inches of each end of each piece of sill plate.
• Minimum 2 bolts per sill plate piece (IRC R403.1.6).
• In high-wind or seismic zones, hold-down devices may be required in addition to standard anchor bolts.

(12 questions, 11% of exam | Based on 2020 NEC / IRC Chapters 34–43)

Key Concepts

Service Entrance & Disconnects

• IRC scope covers 120/240V, single-phase, 0–400 ampere services only (E3401.2). Services over 400A fall outside IRC coverage.
• Service disconnecting means must be located at a readily accessible location — outside or inside nearest the point of entry. Maximum six disconnects per service.
• Minimum service size for new dwellings: 100 amperes, 3-wire (E3601.2).
• Service entrance conductors must be protected from physical damage; overhead clearances apply (10 ft over driveways, 12 ft over residential property, 18 ft over public roads).

Branch Circuit Requirements

• 15A circuits: lighting and general receptacles (14 AWG copper)
• 20A circuits: kitchen small appliances, bathrooms, laundry (12 AWG copper)
• Small appliance branch circuits: minimum two 20A circuits required in kitchen (E3703.2)
• Laundry: one dedicated 20A circuit required (E3703.3)
• Bathroom: one dedicated 20A circuit per bathroom or one 20A circuit supplying only bathroom receptacles
• Each 20A circuit breaker protects 12 AWG wire; each 15A protects 14 AWG — never protect 14 AWG with a 20A breaker

Receptacle Outlet Placement

• In habitable rooms: no point along floor line more than 6 feet from a receptacle; receptacles spaced no more than 12 feet apart (E3901.2)
• Kitchen countertop: receptacle within 2 feet of each countertop end; no point more than 4 feet from a receptacle along countertop wall space
• Bathroom: at least one receptacle within 3 feet of each sink basin
• Garage: at least one receptacle required; outdoors: at least one front and one rear at grade level

GFCI & AFCI Protection

GFCI required locations (E3902): - Bathrooms, garages, outdoors, crawl spaces, unfinished basements, kitchens (within 6 ft of sink), boathouses, near swimming pools, rooftops

Key Concepts

Equipment Sizing

• ACCA Manual J is the industry standard for calculating heating and cooling loads. It accounts for climate, insulation, windows, infiltration, occupancy, and orientation.
• ACCA Manual S is used to select equipment based on Manual J load calculations. Equipment must not be grossly oversized — oversized equipment causes short-cycling, humidity problems, and inefficiency.
• Never size equipment by square footage alone; load calculations must drive selection.

Duct Systems

• Ducts must be constructed of approved materials: sheet metal, rigid fiberglass duct board, or flexible duct (limited use).
• Flexible duct must be fully extended — no compression or sharp bends; max length restrictions apply per manufacturer specs.
• Ducts in unconditioned spaces must be insulated (minimum R-8 in SC climate zones).
• Return air prohibited locations: Bathrooms, toilet rooms, kitchens, garages, furnace rooms, unconditioned attics, and crawl spaces. These spaces cannot serve as return air plenums.
• Supply and return air systems must be balanced; undersized return air is a common installation defect.

Venting Systems for Gas Appliances

• Type B vent: Double-wall, used for natural draft gas appliances (furnaces, water heaters). Not for oil or high-efficiency appliances.
• Type BW vent: Used specifically for wall furnaces.
• Type L vent: Used for oil-burning appliances and certain gas appliances.
• Category I appliances (natural draft, non-positive pressure) use Type B vent.
• Category IV appliances (high-efficiency, positive pressure, condensing) require special PVC or CPVC flue piping — cannot share venting with other appliances.
• Vent termination clearances: Gas appliance vents must terminate at least 12 inches above the roof, 10 feet horizontally from windows/doors/openings, and 3 feet above any opening within 10 feet.
• Direct-vent appliances draw combustion air from outside and exhaust outside — sealed combustion, no indoor air required.

Key Concepts

Governing Codes: SC residential plumbing is governed by the International Residential Code (IRC) and the International Plumbing Code (IPC). Know that local jurisdictions may adopt amendments. Inspections occur at rough-in stage and finish stage (and before concrete pour on slab foundations).

DWV System Materials & Sizing: - Approved DWV materials: PVC, ABS, cast iron, copper (Type DWV) - Minimum drain pipe sizes: lavatory = 1-1/4", toilet = 3", kitchen sink = 1-1/2", shower = 2" - Slope for horizontal drains: 1/4" per foot for pipes 2-1/2" and smaller; 1/8" per foot for 3" and larger - Every fixture trap must connect to a vented drain; traps must be within 24" of the vent

Venting Requirements: - Vent pipes must extend through the roof minimum 6 inches above the roof surface (12" in snow regions) - Minimum vent pipe size: 1-1/4"; toilet requires minimum 2" vent - Stack vents and vent stacks must connect above the highest fixture drain - Wet venting and air admittance valves (AAVs) are permitted under IRC with restrictions

Water Supply System: - Approved supply pipe materials: copper (Type L or M), CPVC, PEX, galvanized steel - Minimum supply pressure: 40 psi at fixtures; maximum: 80 psi (pressure reducing valve required above 80 psi) - Cold water minimum pipe size to fixtures: 1/2"; main service typically 3/4" minimum - Water hammer arrestors required where quick-closing valves are present

Backflow Prevention: - Potable water must be protected from contamination by cross-connection - Hose bibs require vacuum breakers - Toilets and irrigation systems require atmospheric vacuum breakers or RPZ valves depending on hazard level - Air gap is the most reliable form of backflow prevention