Mississippi Residential Builder

Key Concepts

Footings - Footings transmit structural loads to the soil; they must be wider than the foundation wall - Rule-of-thumb residential footing sizing (average soil): - Width = 2× the wall thickness - Depth = equal to wall thickness, minimum 6" - Footing types: plain, reinforced, continuous, stepped, isolated, combined - Stepped footings follow sloping grades; maximum step height is typically 8" per step; on block foundations, use 16" (or multiples) for step length to avoid cutting block - A keyway (groove formed in wet concrete) mechanically bonds the footing to the foundation wall

Frost Protection - Footings must extend below the frost line to prevent heaving from freeze-thaw cycles - Southern climates may only require 12" below frost depth; northern climates can exceed 48" - Always verify local code for the frost depth in the specific jurisdiction — Mississippi's frost depth is minimal but not zero

Mississippi Residential Builder Exam — 10% of Exam (8 Questions)

Key Concepts

Concrete Mixture Components

• Portland cement types: Type I (general use), Type II (moderate sulfate resistance/heat), Type III (high early strength), Type IV (low heat), Type V (high sulfate resistance)
• Water-cementitious materials ratio (w/cm): Lower ratio = higher strength. Typical residential concrete: 0.40–0.50. Maximum w/cm for exposed concrete in freeze-thaw: 0.45
• Aggregates: Fine (sand) and coarse (gravel/crushed stone). Must be clean, hard, and well-graded. Aggregate size should not exceed 1/3 of slab depth, 3/4 of minimum clear spacing between bars, or 3/4 of minimum cover
• Admixtures: Water reducers, retarders, accelerators, air-entraining agents. Added to modify workability, set time, or durability
• Supplementary cementitious materials (SCMs): Fly ash, slag cement, silica fume — replace a portion of Portland cement; improve durability and reduce heat of hydration

Key Concepts

Masonry Unit Types

• CMU (Concrete Masonry Units): Standard hollow or solid concrete block; most common in residential foundation and wall construction. Minimum face-shell thickness and web dimensions govern structural use.
• Clay/Shale Brick: Fired units rated by grade (SW, MW, NW) based on weathering resistance. SW = severe weathering (exterior/below grade); MW = moderate; NW = interior only.
• AAC (Autoclaved Aerated Concrete): Lightweight, highly insulating units; require thin-bed mortar (not standard mortar).
• Natural Stone: Rubble, ashlar, or cut stone; allowable stresses are lower than CMU or brick.

Mortar Types & Proportions

Mortar is specified by Type (ASTM C270), with the acronym MASONWORK helping recall strength order (highest to lowest): M > S > N > O > K

(15 questions, 19% of exam)

Key Concepts

Floor Joists & Sheathing - Joist spans are determined by species, grade, size, and spacing. Use IRC Table R802.4 equivalents for floor joists (typically IRC Chapter 5 tables). Larger spacing = shorter allowable span. - Floor sheathing (subfloor) is rated by span rating (e.g., 24/16, 32/16 — first number = roof span, second = floor span). APA-rated Exposure 1 panels are standard. Minimum 19/32" (5/8") panels at 16" o.c.; 23/32" (3/4") at 19.2" or 24" o.c. - Panel edges must be supported (tongue-and-groove or blocking) unless panels are rated for unsupported edges.

Wall Framing - Standard stud sizes: 2×4 studs allowed up to 10 ft. bearing walls; 2×6 required for taller walls or when specified. - Standard spacing: 16" o.c. typical; 24" o.c. permitted for 2×6 studs in certain conditions. - Headers over openings carry load from above. Size depends on span and load (single vs.…

Key Concepts

Gypsum Board Thickness, Fasteners & Spacing

• Walls: Minimum ½" gypsum board standard; ⅜" permitted over existing surfaces. Use 1¼" Type W (wood) screws for wood framing; 1" Type S screws for steel framing.
• Ceilings: ½" minimum with framing at 16" o.c.; ⅝" required when framing is at 24" o.c. (sag resistance).
• Screw spacing: 16" o.c. on walls and ceilings for field; 12" o.c. at edges/ends when glued; without adhesive, 8" o.c. at edges on ceilings.
• Nail spacing (walls): 8" o.c. for single-layer nailing; double-nailing uses two nails 2" apart, spaced 12" o.c.

Gypsum Board Application — Adhesive vs. No Adhesive

• With adhesive (wood framing): Screw/nail spacing increases to 16" o.c. in the field; adhesive applied in beads to studs.
• Without adhesive: Field fasteners at 8" o.c. (nails) or 12" o.c. (screws) on ceilings; 16" o.c. screws on walls.
• Cold-formed steel framing: Must…

Key Concepts

Roof Covering Types & Minimum Slope Requirements

• Asphalt shingles: minimum 2:12 slope (with double underlayment); standard application at 4:12 and above
• Low-slope asphalt shingles: 2:12 to 4:12 requires two layers of underlayment
• Metal roofing (standing seam): can be applied at slopes as low as ½:12
• Wood shingles: minimum 3:12; wood shakes minimum 4:12
• Clay/concrete tile: minimum 2½:12
• Built-up roofing (BUR): minimum ¼:12 (low-slope/flat applications)

Underlayment Requirements

• Standard asphalt shingles (4:12+): one layer of #15 felt or equivalent synthetic
• Low slope (2:12 to 4:12): two layers of #15 felt, lapped 19 inches, or one layer of #30 felt
• Ice barrier: required in areas subject to ice damming — extends from eave 24 inches inside the exterior wall line
• Underlayment must comply with ASTM D226 (felt) or ASTM D1970 (self-adhering ice barrier)

Key Concepts

Building Permits & Administration (IRC Chapter 1)

• Permit required for all new construction, additions, alterations, repairs, moving, demolition, or change of occupancy of any building or structure
• Exemptions (IRC R105.2): Fences under 7 ft, retaining walls under 4 ft (not supporting surcharge), sheds under 200 sq ft, driveways, painting/papering, replacement of similar materials
• Building Official has authority to interpret and enforce the code, approve alternate materials/methods, stop work orders, revoke permits, and require inspections
• Construction documents must include site plan, floor plans, elevations, sections, and structural details sufficient for the building official to verify code compliance

Required Inspections (IRC R109)

Inspections must occur in sequence; no work shall be covered before inspection approval: 1. Footing – after excavation, before concrete placed 2. Foundation – after foundation is complete 3. Framing – after rough framing, plumbing, mechanical, and electrical are in place 4. Final – after all…

Key Concepts

Fall Protection (OSHA CFR 1926, Subpart M)

• 6-foot trigger height: Any employee in residential construction working 6 feet or more above a lower level must be protected by guardrails, safety nets, scaffolding, or a personal fall arrest system (PFAS) — per §1926.501(b)(13).
• Personal Fall Arrest System (PFAS) components: Body harness (never a body belt), lanyard, deceleration device, and anchorage point. Anchorage must support 5,000 lbs per employee or be designed with a safety factor of 2 under supervision of a qualified person.
• Guardrail specs: Top rail at 42 inches (±3 in.) high; mid-rail at 21 inches. Top rail must withstand 200 lbs of force in any outward/downward direction. Mid-rail must withstand 150 lbs.
• Safety nets: Must be installed as close as practicable but no more than 30 feet below the work surface.

Key Concepts

Building Official Authority (IRC Section R104) The building official is appointed by the jurisdiction (R103.2) and has full authority to enforce the IRC, render code interpretations, issue permits, inspect premises, and issue notices/orders (R104.1–R104.4). Interpretations must align with the code's intent but cannot waive requirements explicitly stated in the code.

Permit Application Requirements (IRC Section R104.2) The building official receives applications, reviews construction documents, and issues permits for erection and alteration. Applications must include sufficient construction documents for plan review before a permit is issued.

Scope of Code Coverage (IRC Section R101.2) The IRC applies to: - Detached one- and two-family dwellings - Townhouses not more than three stories above grade plane - Accessory structures not more than three stories above grade plane - Applies to construction, alteration, movement, enlargement, replacement, repair, demolition, and change of occupancy