Exam Cheat Sheet · Quick Reference

South Carolina Residential Builder

South Carolina  ·  PSI Services Contractor

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
110
Passing score
70%
Exam time
360 min
Administered by
PSI Services Contractor
Format
Reference materials allowed

South Carolina State Portion 110 questions

General Building Construction 74 Q · 67%
General CarpentryConcrete & ReinforcementEstimating and Plan ReadingMasonryRoofingSite Work, Footings and FoundationsFoundation footing design and minimum dimensions by soil bearing capacityConcrete compressive strength requirements by location and weathering exposureFoundation drainage, dampproofing, and waterproofing requirementsSoil types, bearing capacity, and geotechnical evaluationFoundation anchorage of sill plates and anchor bolt requirementsFrost protection and minimum footing depth requirements +2 more
Residential Electrical 12 Q · 11%
Services/Feeders/Branch CircuitsOvercurrent ProtectionGrounding and BondingConductors and CablesRaceways and BoxesLighting and Specialty ApplicationsGFCI and AFCI protection requirements by locationService entrance, sizing, and disconnect requirementsBranch circuit requirements and overcurrent protectionGrounding electrode system and bondingReceptacle outlet placement and spacing requirementsWiring methods and installation requirements +2 more
Residential HVAC 12 Q · 11%
Hangars and SupportsFurnaces and HeatersChimneys, Flues, and VentsCombustion AirDucts, Ventilation and ExhaustFuel Gas and OilPipingEquipment sizing using ACCA Manual J and Manual SCondensate disposal systems and auxiliary drain pansDuct system construction, materials, and installation requirementsReturn air restrictions and prohibited locationsCombustion air requirements for fuel-burning appliances +3 more
Residential Plumbing 12 Q · 11%
General Plumbing and RegulationsPiping/Valves/ControlsFixtures and EquipmentWater SupplyDrain/Waste and Vents/SewersSpecialty ApplicationsDrain, waste, and vent (DWV) system materials and pipe sizingWater supply system design, materials, and pipe sizingPlumbing fixture installation requirements and clearancesInspection and testing of plumbing systemsBackflow prevention and potable water protectionSanitary drainage system design and cleanout requirements +2 more

Key Distinctions

Quantity Takeoff EstimatevsParametric Estimate

A quantity takeoff estimate counts and measures actual materials from completed construction documents, while a parametric estimate uses historical cost-per-unit data before drawings are finalized.

IRC, Section R602.3, Table R602.3(1)
Nominal Lumber DimensionsvsActual (Dressed) Lumber Dimensions

Board-foot calculations use nominal dimensions (e.g., 2×6), not the smaller actual dimensions (e.g., 1½×5½), so the formula is always based on the stated, not measured, size.

IRC, Section R602.1, R602.3
Waterproofing (Foundation)vsDampproofing (Foundation)

Waterproofing is required where a high water table or severe soil-water conditions exist and uses materials such as 40-mil polymer-modified asphalt, whereas dampproofing is used under ordinary conditions.

Section R406.2
Foundation Wall Height – Masonry VeneervsFoundation Wall Height – All Other Conditions

Where masonry veneer is used, concrete/masonry foundation walls must extend at least 4 inches above finished grade; in all other conditions the minimum is 6 inches.

Section R404.1.6
Shed Roof Common RaftervsGable Roof Common Rafter

A shed roof common rafter's total run equals the full building span minus the top-plate width on the higher wall and has two bird's mouths, while a gable roof common rafter's total run is one-half the span and has one bird's mouth.

Carpentry and Building Construction, Page 483
Builder's Level (Dumpy Level)vsTheodolite

A builder's level is a basic optical instrument accurate to ±¼″ at 75 ft, while a theodolite reads horizontal and vertical angles electronically and displays results on an LCD screen for much higher precision.

Carpentry and Building Construction, Chapter 9 — Types of Instruments / Levels
TransitvsBuilder's Level

A transit is classified by the smallest vernier-scale increment it can read (minutes or seconds) and can measure vertical angles, whereas a builder's level is less expensive and limited to horizontal leveling.

Carpentry and Building Construction, Chapter 9 — Types of Instruments / Transits
Setting-Type Joint CompoundvsStandard Drying-Type Joint Compound

Setting-type compound hardens chemically and can set within 1½–2 hours, enabling same-day multi-coat finishing, while standard drying-type compound requires extended drying time between coats.

Finishing Drywall Systems, Chapter 5 — Setting-Type Joint Compounds System Applications, One-Day Finishing section
Floor Plan ViewvsPlot Plan

A floor plan is a horizontal section view looking straight down into the building showing room layout, while a plot plan shows the location of the building on the lot along with land elevations.

IRC, Section R602.3, Figure R602.3(1)
Unit-Cost Estimate – WallsvsUnit-Cost Estimate – Floors/Roofs

In a unit-cost estimate, interior partition walls are measured in lineal feet, whereas floors and roofs are measured in square feet.

Carpentry and Building Construction, Section 2.4, Pages 61-62
Rafter Span Adjustment Factor – Hc/Hr = 1/3vsStandard Rafter Span (No Adjustment)

When ceiling joists or rafter ties are located at one-third the ridge height above the rafter support wall, a 0.67 adjustment factor must be applied, significantly reducing the allowable rafter span versus the unadjusted tabulated span.

IRC, Table R802.4.1(9)
Laser Surveying InstrumentvsOptical Level/Transit

A laser instrument allows a single operator to set up and then move freely using an electronic detector, but its beam is difficult to see in bright daylight, unlike an optical instrument which is always visible through the eyepiece.

Carpentry and Building Construction, Chapter 9 — Types of Instruments / Laser instruments

Key Terms

Ground-Source Heat-Pump Loop Flow/Pressure Test Tolerance International Residential Code, Section M2105.28
Per IRC Section M2105.28, if actual flow rate or pressure drop of a tested loop system differs from calculated design values by more than 10 percent, the cause must be identified and corrective action taken.
Foundation Wall Minimum Height Above Grade (Masonry Veneer) Section R404.1.6
Per IRC Section R404.1.6, concrete and masonry foundation walls must extend at least 4 inches above finished grade where masonry veneer is used.
Foundation Wall Minimum Height Above Grade (General) Section R404.1.6
Per IRC Section R404.1.6, concrete and masonry foundation walls must extend not less than 6 inches above adjacent finished grade in all conditions except masonry veneer.
Waterproofing Requirement (Foundation) Section R406.2
Per IRC Section R406.2, waterproofing rather than dampproofing is required on exterior foundation walls where a high water table or severe soil-water conditions are known to exist.
Joist Framing into Girder Side Support Section R502.6.2
Per IRC Section R502.6.2, floor joists framing into the side of a wood girder must be supported by approved framing anchors or on ledger strips not less than nominal 2×2.
Rafter Span Measurement IRC, Section R802.4.1
Per IRC Section R802.4.1, rafter spans are measured along the horizontal projection of the rafter, not along the actual rafter length.
Footing Size Adjustment for Wide Buildings IRC, Table R403.1(1), footnote (c)
Per IRC Table R403.1(1) footnote (c), for every 4 feet of building width beyond 32 feet, the footing width must increase by 2 inches and footing depth by 1 inch.
Presumptive Load-Bearing Value – Sandy Gravel/Gravel (GW, GP) IRC, Table R401.4.1
Per IRC Table R401.4.1, sandy gravel and/or gravel soils classified as GW and GP have a presumptive load-bearing pressure of 3,000 pounds per square foot.
Quantity Takeoff Estimate IRC, Section R602.3, Table R602.3(1)
An estimate prepared from completed construction documents by counting and measuring the actual quantities of all materials shown on the plans and specifications.
Differential Leveling Carpentry and Building Construction, Chapter 9 — Measuring a Difference in Elevation
A surveying process for determining differences in elevation between remote points that requires one or more additional intermediate instrument setups.
Porosity (Soil) Carpentry and Building Construction, Chapter 9 — The Excavation
The measurement of the ability of water to flow through soil, used to evaluate drainage conditions before construction begins.
Batter Boards Carpentry and Building Construction, Chapter 9 — Setting Up Batter Boards
Temporary boards set on 2×4 stakes driven at least 4 feet beyond each foundation corner, used to hold string lines that define building lines during excavation and layout.
Window and Door Schedules Carpentry and Building Construction, Section 16.2, Page 440
Charts included in building plans that provide rough-opening sizes and other specifications for windows and doors, used during layout and estimating.
Room-Finish Schedule Carpentry and Building Construction, Section 2.3, Page 57
A plan document that identifies the materials and finishes to be used for floors, walls, and ceilings in each room and hallway of a building.
3-4-5 Method Carpentry and Building Construction, Chapter 9 — Setting Up Batter Boards / 3-4-5 Method
A field technique for verifying square corners by measuring 3 units on one leg, 4 units on the adjacent leg, and confirming the diagonal is 5 units (scalable to any multiple, e.g., 9-12-15).

Formulas to Know

Board Feet of LumberBoard feet = (Nominal thickness [in] × Nominal width [in] × Length [ft]) ÷ 12
Excavation Volume (cubic feet)Volume (cf) = (Building length + 2×clearance) × (Building width + 2×clearance) × Depth
Cubic Feet to Cubic Yards ConversionCubic yards = Cubic feet ÷ 27
Excavation Volume with Factor (cubic yards)Cubic yards = Floor area (sf) × Depth factor (cy/sf); e.g., 0.259 cy/sf for 7-ft depth
Drawing Scale ConversionActual length (ft) = Measured drawing length (in) ÷ Scale factor (in/ft); e.g., at ¼" = 1'-0", Actual = Drawing inches ÷ 0.25
Stud Count at 16" OCNumber of studs = (Wall length [ft] ÷ 1.333) + 1
Roof Sheathing Panels with WastePanels needed = (Roof area [sf] ÷ 32) × 1.05 [adds 5% for trim and waste]
3-4-5 Square Check (Pythagorean)Diagonal = √(Leg₁² + Leg₂²); corner is square when diagonal equals the calculated hypotenuse
Rafter Span AdjustmentAdjusted span = Tabulated span × Adjustment factor (e.g., 0.67 when Hc/Hr = 1/3)
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