Arkansas Roofing/Roof Decks - Residential Exam

Roofing/Roof Decks – Residential

Key Concepts

Measuring the roof. Measure the eaves (one direction on a gable roof, two on a hip roof), the width, then the hips and valleys by hooking the tape at a building corner and running to the ridge. Errors in length and width matter most; an error of a foot in a ridge, hip or valley length will not change the bid much, but a 100'×200' roof that is actually 100'6"×200'6" differs by 150 SF, or 1½ squares. Always sketch the roof layout with dimensions, slopes, penetrations and unusual conditions (Roofing Construction & Estimating, Chapter 1, Page 6).

Level roof area. Area of a level rectangular roof = L × W (Equation 1-1). For irregular level roofs there are two approaches that give identical results (Chapter 1, Pages 7-8): - Positive method — divide the roof into rectangles, compute each area, and add them (Example 1-1). - Negative method — extend the roof lines to form one rectangle, compute its area, and subtract the rectangular areas lying outside the actual roof (Example 1-2). Use whichever requires the fewest calculations.

Slope. Slope is rise in inches per 12 inches of run: Slope = Total Rise ÷ Total Run, expressed over 12 (Equation 1-4, Page 1-4). Pitch = Total Rise ÷ Total Span, and Slope = 2 × Pitch (Equations 1-5, 1-6). In conventional framing, the unit run of a common rafter (90° to the ridge) is always 12"; for a rafter at 45° to the ridge (a hip) it is 17" (Carpentry and Building Construction, Section 17.1, Page 470).

Arkansas Roofing/Roof Decks – Residential | 4 questions (13%)

Key Concepts

Deck inspection before work begins. NRCA recommends the roofing contractor, with the appropriate parties (general contractor, deck contractor, architect/engineer or designer, owner's representative), make a visual inspection of the deck surface to verify it is clean, dry, smooth and ready for roof system application. The deck should be broom clean, reasonably smooth, free of voids or depressions, and adequately attached, and should remain rigid so as not to deflect excessively under live loads. A roofing contractor can only inspect the surface and cannot assume responsibility for the deck's slope, structural integrity, method of attachment, or conditions beyond his or her control. Visible defects should be noted and corrected before roofing begins, then a second inspection made, attended by the same parties. (NRCA Steep-slope Roof Systems—2025, Chapter 2—Roof Decks)

Plywood thickness by rafter spacing. For asphalt shingle roof systems, NRCA recommends four-ply, nominal ¾-inch (actual 23⁄32-inch) plywood for 24-inch rafter spacings. For metal shingle roof systems, NRCA recommends a minimum of four-ply, nominal ⅝-inch (actual 19⁄32-inch) plywood for 16-inch rafter spacings and four-ply, nominal ¾-inch (actual 23⁄32-inch) plywood for 24-inch rafter spacings. (Section 2.1—Wood Panels)

OSB minimum. If OSB is installed for roof sheathing, use a minimum 7/16-inch (nominal) panel. (Roofing Construction and Estimating, Chapter 2) Note separately that NRCA does not recommend OSB as a substrate for metal shingle or for clay/concrete tile roof systems. (NRCA Section 2.1)

Panel edge clips. NRCA recommends panel edge clips when wood panel sheathing of ½-inch nominal thickness (actual 15/32-inch) or less is installed over supporting members spaced at 24 inches on center. (Section 2.1—Wood Panels)

Roofing and Roof Decks — Residential

Key Concepts

Roof slope categories and shingle selection - Three basic slope categories: flat = below 2½-in-12; low slope = between 2½-in-12 and 4-in-12; high slope = 4-in-12 or greater (Carpentry and Building Construction, Section 22.1 — Roof Slope). - Strip shingles are installed on roofs with a slope of 4-in-12 or greater; consult the shingle manufacturer's literature for advice on lower slopes (Section 22.2 — Installation Issues). - NRCA: laminated and specialty shingles should not be used on slopes less than 4:12 because irregular shapes/thicknesses create unpredictable drainage paths; three-tab shingles are more suitable for lower slopes (NRCA Steep-slope, Section 3.2 — Roof Slope).

Underlayment - Single-coverage felt: No. 15 felt rolled from the eave line upward, top lap at least 2" at horizontal joints and 4" side lap at end joints (Carpentry, Section 22.2 — Installing Underlayment). - NRCA single-layer: minimum 2" side laps, minimum 4" end laps; some synthetic manufacturers call for minimum 3" side laps and 6" end laps — verify product-specific recommendations (NRCA Section 3.2 — Single Layer Mechanically Attached). - Double-layer: begin with a half-width plus 1 inch strip parallel to the eave; each subsequent sheet laps a minimum of half the sheet width plus 1 inch (NRCA Section 3.2 — Double Layer Mechanically Attached). - IBC 2024 / IRC 2024, outside high-wind regions: single layer mechanically attached at slopes 4:12 and greater; double layer mechanically attached at slopes 2:12 to 4:12 (NRCA Section 3.2). - Taped deck: minimum 4-inch-wide ASTM D1970-compliant self-adhering flashing tape over all sheathing joints, then a single layer of mechanically attached underlayment (NRCA Section 3.2 — Taped Deck). - Synthetic sheet…

Key Concepts

Deck slope and underlayment by covering - Asphalt shingle deck slope must be 2:12 or greater; slopes of 2:12 to 4:12 additionally require double-layer underlayment (IRC 2024, Section R905.2.2; IBC 2024, Section 1507.2.2). - Clay and concrete tile at 2½:12 to 4:12 require two layers of underlayment applied shingle fashion; a single layer is permitted at 4:12 or greater in normal ultimate design wind speed regions, and cap-fastener attachment applies in high-wind regions (IRC 2024, Section R905.3.2 and Table R905.1.1(2)). - Slate requires solidly sheathed decks and a deck slope of 4:12 or greater (IBC 2024, Sections 1507.7.1 and 1507.7.2; IRC 2024, Sections R905.6.1 and R905.6.2). - In high ultimate design wind speed regions, mechanically attached underlayment is fastened with corrosion-resistant metal or plastic cap fasteners at 6 inches on center at side and end laps and a 12-inch on-center pattern in the field; where self-adhering underlayment is used, fastening is not required (IRC 2024, Table R905.1.1(3); IBC 2024, Table 1507.1.1(3)).

Material standards - Clay tile: ASTM C1167; concrete tile: ASTM C1492; asphalt shingles: ASTM D3462; self-adhering underlayment: ASTM D1970 (IRC 2024, Section R905.3.4; IBC 2024, Section 1507.3.4). Slate shingle products must comply with ASTM C406 (IBC 2024, Section 1507.7.5; IRC 2024, Section R905.6.4).

Key Concepts

Safety training and education — employer responsibility (§1926.21(b))

• The employer shall instruct each employee in the recognition and avoidance of unsafe conditions and the regulations applicable to his work environment to control or eliminate any hazards or other exposure to illness or injury. (§1926.21(b)(2))
• Employees required to handle or use poisons, caustics, and other harmful substances shall be instructed regarding the safe handling and use, and be made aware of the potential hazards, personal hygiene, and personal protective measures required. (OSHA 1926 CFR 29, §1926.21(b)(3))
• In job site areas where harmful plants or animals are present, exposed employees shall be instructed regarding the potential hazards, how to avoid injury, and the first aid procedures to be used in the event of injury. (§1926.21(b)(4))
• Employees required to handle or use flammable liquids, gases, or toxic materials shall be instructed in the safe handling and use of these materials and made aware of the specific requirements contained in subparts D, F, and other applicable subparts. (OSHA 1926 CFR 29, §1926.21(b)(5), Page 30)

Housekeeping (§1926.25)

• Form and scrap lumber with protruding nails, and all other debris, shall be kept cleared from work areas, passageways, and stairs, in and around buildings or other structures. (§1926.25(a))
• Combustible scrap and debris shall be removed at regular intervals during construction. (§1926.25(b))
• Containers used for garbage and other oily, flammable, or hazardous wastes, such as caustics, acids, harmful dusts, etc. shall be equipped with covers. Garbage and other waste shall be disposed of at frequent and regular intervals. (OSHA 1926 CFR 29, §1926.25(c))

Personal protective equipment (§1926.28)