Mississippi Residential Builder

Key Concepts

Footing minimums. Footing width (W) and thickness (T) come from Tables R403.1(1) through R403.1(3), but never less than 12 inches wide and 6 inches deep, regardless of soil value or building configuration. Footing projection (P) shall be not less than 2 inches and shall not exceed the thickness of the footing (IRC R403.1.1). Width is based on the load-bearing value of the soil per Table R401.4.1.

Depth and frost. Exterior footings shall be placed not less than 12 inches below the undisturbed ground surface (R403.1.4). Frost protection is achieved by extending below the frost line in Table R301.2, complying with R403.3, complying with ASCE 32, or erecting on solid rock (R403.1.4.1). The jurisdiction fills in the frost line depth column of Table R301.2 (Table R301.2, Note b). Frost-protected shallow foundations require a building monthly mean temperature of not less than 64°F (18°C) and shall not be used for unheated spaces such as…

Topic: Concrete and Concrete Reinforcement

Key Concepts

Cement types - Type III is high-early-strength cement: it reaches in 7 days approximately the same strength that Type I (general-purpose) reaches in 28 days; beyond 2 or 3 months there is little difference in long-term strength. (Contractor's Guide, pp. 14–15)

Water-cementitious materials ratio (w/cm) - With SCMs, w/cm = weight of water ÷ total weight of all cementitious materials (portland cement + fly ash + slag + silica fume, etc.). Example: 270 ÷ (425 + 125) = 0.49. (Contractor's Guide, p. 36) - Exposure limits from Table 2.5: Category F3 (freeze-thaw, frequent water, plus deicing chemicals) — max w/cm 0.40, min 5000 psi. Category W1 (in contact with water, low permeability required) — max w/cm 0.50, min 4000 psi. Sulfate class S2 (1500–10,000 ppm dissolved sulfate) — max w/cm 0.45, min 4500 psi. (Contractor's Guide, p. 24, Table 2.5)

Key Concepts

Masonry units and standards - A solid masonry unit is "one whose cross-sectional area in every plane parallel to the bearing surface is 75% or more of its gross cross-sectional area measured in the same plane." Cored brick still counts as solid if holes are under 25% (Modern Masonry, p. 123). - A hollow masonry unit has less than 75% solid material in its net cross-sectional area in any plane (Modern Masonry, p. 123). - Building brick grades: Grade SW is highly resistant to frost action, for brick exposed to freezing weather such as foundation courses or retaining walls; Grade MW for moderate exposure; Grade NW for interior backup masonry (Modern Masonry, p. 116). - Green bricks are bricks not yet fired; they contain 5% to 30% moisture as they come from the molding or extruding machines (Modern Masonry, p. 115). - Masonry systems used for foundations must have a minimum specified…

Key Concepts

Floor joists and spans - Table R502.3.1(1) governs joists supporting sleeping areas and attics accessed by a fixed stairway, provided design live load ≤ 30 psf and dead load ≤ 20 psf (R502.3.1). Table R502.3.1(2) covers other living areas, live load not exceeding 40 psf, dead load ≤ 20 psf (R502.3.2). - Floor cantilever spans shall not exceed the nominal depth of the wood floor joist (R502.3.3). - Bearing: ends of each joist, beam or girder need not less than 1½ inches of bearing on wood or metal, 3 inches on masonry or concrete, or approved joist hangers (R502.6). - Joists lapping from opposite sides over a bearing support: lap not less than 3 inches, nailed with a minimum three 10d face nails (R502.6.1). - Joists framing into the side of a wood girder: approved framing anchors or ledger strips not less than nominal 2×2 (R502.6.2). - Double joists under parallel bearing…

Key Concepts

Interior plaster - Gypsum plaster: not less than three coats over metal lath, not less than two coats over other permitted bases; veneer plaster in one coat not exceeding 3/16 inch (R702.2.1, PDF p. 349). - Cement plaster is likewise three coats over metal lath, two coats over other permitted bases (R702.2.2). - Interior cement plaster curing (R702.2.2.2, PDF p. 350): two-coat — finish coat not sooner than 48 hours after the first coat; three-coat — second coat not sooner than 24 hours after the first, finish coat not sooner than 48 hours after the second. Each coat kept moist not less than 24 hours (R702.2.2.1), except applications per ASTM C926. - Lath support spacing: 16 inches for 3/8-inch-thick, 24 inches for 1/2-inch-thick plain gypsum lath, installed at right angles to framing with end joints staggered (R702.2.3, PDF p. 350).

Key Concepts

Minimum slopes by covering - Asphalt shingles: 2:12 or greater; slopes from 2:12 up to 4:12 require double underlayment (R905.2.2). - Clay and concrete tile: 2½:12 (25-percent slope) or greater (R905.3.2). - Wood shingles: 3:12 or greater (R905.7.2). - Standing-seam metal roof systems: 1/4:12 (2-percent slope) (R905.10.2, Item 3).

Underlayment - Underlayment must be applied per Table R905.1.1(2) and attached per Table R905.1.1(3) (R905.1.1). - Asphalt shingles, 2:12 to 4:12: two layers — start with a 19-inch strip at the eaves, then 36-inch-wide sheets overlapping successive sheets 19 inches; end laps 4 inches, offset 6 feet (Table R905.1.1(2)). - Where wind design is required, underlayment is attached with annular ring or deformed shank nails with 1-inch-diameter metal or plastic caps (Table R905.1.1(3)). - Underlayment goes over the drip edge at eaves and under the drip edge at rake edges (R905.2.8.5).

Key Concepts

Administration and permits - Fences not over 7 feet high are exempt from permit requirements. One-story detached accessory structures are exempt only if floor area does not exceed 200 square feet; retaining walls only if not over 4 feet in height; decks only if not exceeding 200 square feet and not more than 30 inches above grade (IRC R105.2). - The building official may render interpretations (R104.1), grant modifications for practical difficulties (R104.10) and approve alternative materials and methods (R104.11), but interpretations, policies and procedures shall not have the effect of waiving requirements specifically provided for in the code (R104.1). - Precast concrete foundation wall design drawings must be submitted to the building official and approved prior to installation (R404.5.2). - Slab-on-ground systems that have performed adequately in similar soils may be used on expansive soils subject to approval of the building official (R403.1.8 Exception).

6 verified practice questions

Key Concepts

Fall protection trigger height (residential construction). Each employee engaged in residential construction activities 6 feet or more above lower levels shall be protected by guardrail systems, scaffolding, a safety net system, or a personal fall arrest system. (29 CFR 1926, §1926.501(b)(13); BCSI B11 Fall Protection & Trusses, Page 89)

Guardrail top rail strength. Guardrail systems shall be capable of withstanding, without failure, a force of at least 200 pounds (890 N) applied within 2 inches of the top edge, in any outward or downward direction, at any point along the top edge. (§1926.502(b)(3)) Midrails and intermediate structural members are held to the 150-pound requirement. (§1926.502(b)(5))

Asbestos — 8-hour TWA PEL. The employer shall ensure that no employee is exposed to an airborne concentration of asbestos in excess of 0.1 fiber per cubic centimeter of air as an 8-hour time-weighted average. (§1926.1101(c)(1))

Mississippi Residential Builder

Key Concepts

Permit application contents (R105.3). The application must identify and describe the work, describe the land on which the proposed work is to be done, indicate the use and occupancy, be accompanied by construction documents, state the valuation of the proposed work, be signed by the applicant, and give any other data required by the building official. An estimated completion date is not a required item.

Abandoned applications (R105.3.2). An application is deemed abandoned 180 days after the date of filing unless it has been pursued in good faith or a permit has been issued. The building official may grant extensions of up to 180 days each.

Work exempt from permit (R105.2). Exemptions include fences not over 7 feet high, accessory structures not exceeding 200 square feet, retaining walls not over 4 feet, and decks not attached to a dwelling.