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C. From shingle course to shingle course upwards on roof deck, end joints must be maintained with a horizontal offset of 5-5/8 inches. D. Ventilation: Provide minimum of 1 square feet of total net free ventilating area for each 150 square feet of ceiling area, or 1 square foot for each 300 square feet of ceiling area if either a vapor barrier is installed on warm side of ceiling area or if approximately one-half the ventilation is provided near roof ridge. 3.3 UNDERLAYMENT A. Roof decks with pitch of 4-inches per foot or greater,for new construction or when old roofing has been removed, apply a single layer of felt underlayment complying with ASTM D226, D4869 or D6757 and local building code. Specifier Note: For slopes at least 4-inches per foot, PABCO®recommends single layer felt underlayment. 1. [Single Layer Felt Underlayment: Apply underlayment with 2-inch wide top laps and 4-inch wide end laps. Lap felt underlayment a minimum of 6-inches from both sides overall hips, ridges and valleys.] Specifier Note: On slopes between 2 inches and 4 inches per foot, PABCO®recommends self-adhering underlayment or double layer felt underlayment. B. Roof decks with pitch of greater than 2-inches per foot and less than 4-inches per foot,for new construction or when old roofing has been removed, apply underlayment: 1. [Self-Adhering Underlayment: Apply self-adhering underlayment according to underlayment manufacturer's written instructions and in compliance with local building code.] 2. [Double-Layer Felt Underlayment: Apply a first course of underlayment with 19-inch wide top laps and 12-inch wide end laps. Over this, apply a full 36-inches wide sheet. Continue 36-inches wide sheets, lapping each 19- inches over the preceding course.] 3.4 EAVE FLASHING A. Install self-adhering underlayment as an eave flashing for ice dam protection in areas of winter temperatures averaging 30°F or less, applied parallel to the eave. Eave flashing overhangs drip edge 1/4-inch to 3/8-inch and extends up the roof to at least 24-inches inside the interior wall line. Horizontal (top)overlaps(when needed), should be located over the overhang area. Top laps are at least 2-inches, end laps are at least 6- inches. B. Eave Drip Edges: Install eave drip edge flashings below underlayment and fasten to roof sheathing. 3.5 NAILING INSTRUCTIONS A. Use four nails per shingle for normal application, positioned in the nail zone as recommended by shingle manufacturer. Nails shall be at least 1 inch long, aluminum or galvanized, 3/8-inch head, 11or 12-gauge roofing nails. Nails must be driven flush with shingle surface. NAILS MUST NOT BE OVERDRIVEN TO CUT INTO SHINGLES. Specifier Note: See the PABCO Tahoma® Application Details—Nailing Instructions for additional details at www.oabcoroofing.com. B. Special Applications: 1. High Wind Application: For areas where local knowledge indicates exposure to high winds may occur, shingles must be applied with 6 nails spaced according to shingle manufacturer's written instructions and sealed to qualify for wind damage warranty coverage. 2. Steep Slope Application: On slopes greater than 21-inches per foot(Mansard type roofs), 6 nails are required, spaced according to shingle manufacturer's written instructions.These shingles are to be hand sealed at the time of application with asphalt roof cement, by applying 6 spots about the size of a quarter, located under the shingle tab corners. 3.6 VALLEYS Specifier Note: Closed-cut valleys are recommended by PABCO®; woven valleys are also accepted. A. Closed-cut Valleys: 1. Valley Flashing: Valley starts with 36-inches self-adhered, bottom layer underlayment centered down the valley. Extend felt underlayment from the field over this and trim overlap 6-inches. A second underlayment layer(ASTM D4869 Type II or heavier) is applied over this, centered down the valley. Lay the first course of shingles along the eaves of one roof plane and over the valley, extending it into the Project Name/Project Number/Insert Date Revised 11/17/20-Page 5 ASPHALT SHINGLES PABCO®Roofing Products