Georgia Residential Basic Contractor Exam

Key Concepts

Drainage and Grading (R401.3) Lots must be graded so surface water drains away from foundation walls. Minimum slope: 6 inches of fall within the first 10 feet from the foundation. Where barriers prevent this, drains or swales must be used. Impervious surfaces within 10 feet must slope at least 2% away from the building.

Soil Testing (R401.4) Soil tests are required when expansive, compressible, or shifting soils are likely present — determined by the building official. If a full geotechnical evaluation isn't done, use the presumptive load-bearing values in Table R401.4.1.

Presumptive Soil Bearing Capacities (Table R401.4.1): - Crystalline bedrock: 12,000 psf - Sedimentary/foliated rock: 4,000 psf - Sandy gravel/gravel (GW, GP): 3,000 psf - Sand, silty/clayey sand, silty/clayey gravel (SW, SP, SM, SC, GM, GC): 2,000 psf - Clay, sandy clay, silty clay, silt (CL, ML, MH, CH): 1,500 psf - If bearing capacity is likely less than 1,500 psf, a soils investigation is mandatory.

Georgia Residential Basic Contractor Exam | 10% of Exam (8 Questions)

Key Concepts

Concrete Mixture & Compressive Strength (IRC R402.2) - Concrete must meet minimum specified compressive strength (f'c) per Table R402.2 based on location and exposure (weathering zone) - Georgia is generally a moderate-to-severe weathering region — air entrainment is required for exposed concrete - Precast concrete foundations: minimum 5,000 psi at 28 days (R402.3.1) - Garage floors, exterior porches, carport slabs, and steps exposed to deicing chemicals have limits on fly ash, pozzolans, silica fume, and slag per ACI 318 Section 19.3.3.4

Portland Cement & Admixtures - Five primary Portland cement types: Type I (general use), Type II (moderate sulfate resistance), Type III (high early strength), Type IV (low heat), Type V (high sulfate resistance) - Supplementary cementitious materials (SCMs): fly ash, slag, silica fume — reduce permeability and heat of hydration but are restricted in freeze-thaw/deicing applications - Water-cement ratio is the single biggest factor controlling strength: lower w/c = higher strength

Key Concepts

Mortar Types, Mixing, and Properties

Mortar is classified by ASTM C270 into four types based on compressive strength and use: - Type S – High strength (1,800 psi min); used below grade, in contact with soil, and for exterior masonry. Most common for residential foundations. - Type M – Highest strength (2,500 psi min); used for unreinforced masonry below grade and in contact with earth. - Type N – Medium strength (750 psi min); general-purpose above-grade exterior and interior walls. - Type O – Low strength (350 psi min); interior non-load-bearing walls only.

Memory trick: "Mason's Mortar Never Outlasts" → M, S, N, O (strongest to weakest).

Brick Types and Classifications

Bricks are classified by durability grade: - Grade SW (Severe Weathering) – Used below grade or where exposed to freezing and thawing. - Grade MW (Moderate Weathering) – Above grade in moderate climates. - Grade NW (Negligible Weathering) – Interior use only.

Standard brick nominal dimensions: 2⅔" H × 4" W × 8" L (with mortar joint).

Study Brief (20% of Exam – 16 Questions)

Key Concepts

Wood Framing Members & Lumber Grades - All sawn lumber must be identified by a grade mark from an accredited agency complying with DOC PS 20 (IRC R502.1.1, R602.1.1). A certificate of inspection is an acceptable substitute. - Preservative-treated lumber must meet Section R317.2 requirements. - End-jointed lumber may substitute for solid-sawn of the same species/grade; fire-rated assemblies require "HRA" (Heat Resistant Adhesive) in the grade mark. - Prefabricated wood I-joists: governed by ASTM D5055. Glulam: ANSI A190.1 / ASTM D3737. Structural composite lumber: ASTM D5456.

Floor Framing Systems (IRC Chapter 5) - Floor joists span limits are determined from Tables R502.3.1(1) and R502.3.1(2). - Table (1): sleeping areas and attics with fixed stair access — max live load 30 psf, max dead load 20 psf. - Subflooring minimum grade: utility grade lumber, No. 4 common boards, or rated wood structural panels (R502.2.2). - Blocking for fastening panel edges must be not less than utility grade lumber. Fireblocking may be any grade.…

Key Concepts

Roof Framing Terminology - Span: total width of the building (outside to outside of top plates) - Run: half the span (horizontal distance a rafter covers) - Rise: vertical height from top plate to ridge - Slope: expressed as rise over run (e.g., 6:12 = 6" rise per 12" run) - Pitch: rise divided by full span (less commonly used in field; don't confuse with slope) - Unit run: always 12" for common rafters; unit rise: inches of rise per 12" of run

Rafter Layout Methods - Pythagorean theorem: rafter length² = run² + rise² (gives true line length) - Unit-length method: use rafter tables on a framing square; multiply unit length × number of feet of run - Step-off method: "step" the framing square along the rafter one foot of run at a time - Bird's mouth: the notch cut where the rafter seats on the top plate; consists of a plumb cut (heel) and a level cut (seat) - Shortening: at the ridge, shorten each rafter by half the…

Georgia Residential – Basic Contractor Exam | 18 Questions | 22% of Exam

Key Concepts

IRC 2018 Scope (Section R101.2) Applies to detached one- and two-family dwellings and townhouses not more than 3 stories above grade plane with a separate means of egress. Accessory structures also covered. Exceptions allow some care facilities and live/work units under IRC if equipped with a residential fire sprinkler system (Section P2904).

Applicability Rules (Section R102) - Conflict between general vs. specific requirement → specific governs - Conflict between IRC and a referenced standard → IRC governs - Appendices are not enforceable unless specifically adopted by local ordinance - Existing structures may continue legal occupancy without change; additions/alterations must conform to requirements for a new structure but do not require the entire existing structure to be brought into compliance

Permits and the Building Official - Building official enforces the code, issues permits, conducts inspections, and renders interpretations (R104.1–R104.4) - Permits required for construction, alteration, movement, enlargement, repair, demolition

10 questions | 12% of exam weight

Key Concepts

Interior Wall & Ceiling Surfaces

• Gypsum board is the dominant interior finish material. Standard thickness is ½ inch for walls, ⅝ inch for fire-rated assemblies.
• Plaster systems: 3 coats required over metal lath; 2 coats over other bases (gypsum lath, masonry). Veneer plaster = 1 coat, max ³⁄₁₆ inch thick (IRC R702.2.1).
• Cement plaster curing (R702.2.2.2): 2-coat system — finish coat not before 48 hours after first coat. 3-coat system — second coat not before 24 hours; finish coat not before 48 hours after second coat.
• Gypsum lath support spacing: max 16 inches for ⅜-inch lath; max 24 inches for ½-inch lath (R702.2.3).

Exterior Siding

• Water-resistive barrier (WRB) is required behind all exterior cladding (IRC R703.2).
• Exterior sheathing must be dry before applying exterior cover (R701.2).
• Common materials: vinyl, fiber cement, wood, hardboard, aluminum, stucco. Each has specific fastening and clearance requirements.
• Minimum 6-inch clearance from siding to grade is standard to prevent moisture/rot.…

7 questions | 9% of exam | Reference: 29 CFR 1926

Key Concepts

Fall Protection (Subpart M)

• Trigger height for residential construction: 6 feet. Any worker exposed to a fall of 6 feet or more must be protected by guardrails, safety nets, or a personal fall arrest system (PFAS).
• Guardrail height: 42 inches (±3 inches) with midrail at approximately 21 inches. Top rail must withstand 200 lbs of force.
• Personal Fall Arrest Systems: Must limit free fall to 6 feet, limit deceleration force to 1,800 lbs, and arrest a fall before the worker contacts a lower level. Anchor must support 5,000 lbs per worker.
• Safety nets: Must be installed as close as practicable under the walking/working surface, never more than 30 feet below.