ICC G15 Shingle Roofing Exam (2018 IBC/IRC)

2018 International Building Code / 2018 International Residential Code

Key Concepts

Code applicability - Detached one- and two-family dwellings and townhouses not more than three stories above grade plane with a separate means of egress, and their accessory structures not more than three stories above grade plane, may comply with either the IBC or the IRC (IBC 101.2 Exception; IRC R101.2). - Change in character or use of an existing structure: only as specified in Sections 407 and 408 of the International Existing Building Code (IRC R110.2).

Permits - IRC R105.2 (Building item 1): no permit for one-story detached accessory structures provided floor area does not exceed 200 square feet. (IBC 105.2 uses 120 square feet for structures under the Building Code.) Exemption never authorizes work in violation of the code. - IBC 105.2 Building item 2: fences not over 7 feet high are exempt. - IBC 105.2 Building item 12: window awnings in Group R-3 and U are exempt only if supported by an exterior wall, projecting not more than 54 inches, and requiring no additional support — ground posts void the exemption. - IBC 105.1.1: an annual permit may be issued only in lieu of individual permits for each alteration to an already approved electrical, gas, mechanical or plumbing installation, to a person/firm regularly employing qualified tradepersons; IBC 105.1.2 requires a detailed record of alterations. - IBC 105.3 application contents: identification/description of work; description of land; intended use and occupancy; construction documents; valuation; applicant's signature; other data required by the building official. No completion date is required. - IBC 105.3.2: application abandoned 180 days after filing; building official may grant written extensions not exceeding 90 days each. - IBC 105.5: permit invalid if work not commenced within 180 days or suspended/abandoned 180 days; extensions not more than 180 days each. - IRC R107.1: temporary structure/use permits shall not be permitted for more than 180 days; extensions for demonstrated cause, termination under R107.4.

Key Concepts

Asphalt shingles - Minimum slope: two units vertical in 12 units horizontal (17-percent slope) — IBC 1507.2.2. Per IRC R905.2.2, asphalt shingles are permitted only on slopes of 2:12 or greater, and double underlayment is required for slopes from 2:12 up to 4:12. - Where the slope exceeds 21 units vertical in 12 units horizontal (175-percent slope), shingles shall be installed per the manufacturer's approved installation instructions — IRC R905.2.6 / IBC 1507.2.6. - Fasteners: galvanized steel, stainless steel, aluminum or copper roofing nails, minimum 12 gage [0.105 inch] shank with minimum 3/8-inch-diameter head — IRC R905.2.5 / IBC 1507.2.5; IRC R905.2.5 adds compliance with ASTM F1667. - Minimum number of fasteners: as required by the manufacturer, but not less than four per strip shingle or two per individual shingle — IBC 1507.2.6. - Material standard: ASTM D3462 — IBC 1507.2.4 / IRC R905.2.4. - Wind resistance: tested per ASTM D7158, meeting Table 1504.1.1 classification; packaging labeled to show compliance and the required classification — IBC 1504.1.1; IRC R905.2.4.1. Exception: shingles outside the scope of D7158 are tested and labeled to ASTM D3161. - Open valley lined with metal: lining not less than 24 inches wide, corrosion-resistant metal from Table 1507.2.8.2 — IBC 1507.2.8.2, Item 1. - Ice barrier (IRC R905.1.2): extends from the lowest edges of the roof surface to at least 24 inches inside the exterior wall line; on slopes of 8:12 or greater, also not less than 36 inches measured along the roof slope from the eave edge.

2018 IBC / 2018 IRC

Key Concepts

Fastener type, length, deck penetration - Asphalt shingle fasteners: galvanized steel, stainless steel, aluminum or copper roofing nails, minimum 12-gage [0.105 inch] shank with minimum 3/8-inch-diameter head, complying with ASTM F1667 (IRC R905.2.5; IBC 1507.2.5). Length must penetrate through the roofing materials and not less than 3/4 inch into the sheathing; where sheathing is less than 3/4 inch thick, penetrate through it (IRC R905.2.5). - Clay/concrete tile nails: corrosion resistant, not less than 11-gage, of sufficient length to penetrate the deck not less than 3/4 inch or through the deck, whichever is less (IRC R905.3.6). Caution: the SOURCE's verified questions give the head size for R905.3.6 as 7/16 inch in one item and 5/16 inch in another — know both figures with the 11-gage shank. Attaching wire for clay or concrete tile shall not be smaller than 0.083 inch (IRC R905.3.6; IBC 1507.3.6). - Underlayment cap nails: not less than 0.083 inch (ring shank) and 0.091 inch (smooth shank); plastic cap outside-edge thickness not less than 0.035 inch; metal caps not less than 32-gage sheet metal; power-driven metal caps not less than 0.010 inch (IBC 1507.1.1 Exc. 3 and Table 1507.1.1(3) for V ≥ 140 mph; IRC R905.1.1 Exc. 3.4). - Wood shingles/shakes: not fewer than two fasteners each, minimum 3/4-inch penetration into sheathing; where sheathing is less than 1/2 inch thick, fasteners extend through (IBC 1507.8.6, 1507.9.7). Hot-dipped galvanized or Type 304 stainless; Type 316 for coastal areas (IBC Table 1507.8). IRC R905.7.5: Type 316 within 15 miles of saltwater coastal areas; alternative two 16-gage stainless staples, crown 7/16 inch minimum to 3/4 inch maximum. Fire-retardant-treated shakes: Type 316 (IRC R905.8.6).

Key Concepts

Scope and general compliance - Materials and methods of application used for re-covering or replacing an existing roof covering shall comply with the requirements of the roof assemblies chapter — IRC Chapter 9 (IRC R908.1 General) and IBC Chapter 15 (IBC 1511.1 General). The current code's roof assembly requirements govern, not the code the original roof was built under. - Exception 1: Reroofing is not required to meet the minimum design slope requirement of one-quarter unit vertical in 12 units horizontal (2-percent slope) of Section R905 / Section 1507 for roofs that provide positive roof drainage (IRC R908.1 Exc. 1; IBC 1511.1 Exc. 1). - Exception 2: For roofs with positive drainage, re-covering or replacing an existing roof covering does not require the secondary (emergency overflow) drains or scuppers of Section R903.4.1 to be added to an existing roof (IRC R908.1 Exc. 2).

Structural and construction loads (IRC R908.2) - Structural roof components shall be capable of supporting the roof covering system and the material and equipment loads that will be encountered during installation of the roof covering system.

Roof replacement (IRC R908.3; IBC 1511.3) - Existing layers are removed down to the roof deck. Exception: where the existing roof assembly includes an ice barrier membrane adhered to the roof deck, that membrane is permitted to remain in place and be covered with an additional layer of ice barrier membrane installed in accordance with Section R905 (IRC) / Section 1507 (IBC). No such allowance exists for base sheets, insulation or other underlayments.