TB-10024108 TECHNICAL BULLETIN OWENS CORNING'S RECOMMENDATIONS AND DETAILS FOR INSTALLATION OF OPEN VALLEYS APRIL 3, 2020 ­ SUPERSEDES PREVIOUS BULLETINS Open Valleys: The valley must be covered with a self-adhered underlayment that is a minimum of 36 inches wide. The self-adhered underlayment must meet ASTM D1970. Center the self-adhered underlayment in the valley, securing with only enough nails to hold it in place. All end laps should overlap 6 inches. Install a minimum 26-gauge metal flashing that is at least 24 inches wide. Center the metal flashing in the valley. Trim the lower edge flush with the eave drip edge. If two or more pieces of flashing are required, lap the upper piece over the lower so that drainage will be carried over the joint, not into it. The overlap should be at least 12 inches and fully bonded with ASTM D4586 roofing cement. Nails should be placed 8 to 12 inches apart, and 1 inch from the edge. Start on one side and work all the way up. Then return to nail the other side, pressing the flashing firmly into the valley at the same time. It is recommended to snap a chalk line 3 inches on either side Underlayment laps 6 Self-adhered underlayment of the valley from top to bottom, diverging an 1/8 inch per foot. over self-adhered underneath valley metal Install a bleeder shingle along the chalk lines, with the head lap underlayment away from the chalk line. Install with a standard nailing pattern. 6 Valley Install full shingles with the bottom corner to the edge of the centerline bleeder shingle. Use the standard nailing pattern, except for the Chalk lines diverge nail closest to the valley. Install this nail in the nail line of the per foot Metal valley bleeder below. flashing Underlayment 12" top lap Roofing cement is not recommended or required with this application. Installing roofing cement can trap water at bleeder Fastener should be end joints if installed incorrectly. If roofing cement is installed aligned with nail line under the bleeder shingles, it must be installed at or above the of the bleeder shingle nail line. Keep in mind, with certain roof pitches, running the book pattern from the bleeder can affect shingle offset. Shingle offset can be no less than 4 inches for correct installation. End shingles trimmed to chalk line. Roofing cement not recommended or required. Please contact 419-248-6557 for additional information. OWENS CORNING SCIENCE AND TECHNOLOGY, LLC Email: gettech@owenscorning.com ONE OWENS CORNING PARKWAY TOLEDO, OHIO 43659 Disclaimer of Liability 1-800-GET-PINK® Technical information contained herein is furnished without charge or obligation and is given and www.owenscorning.com accepted at recipient's sole risk. Because conditions of use may vary and are beyond our control, Owens Corning makes no representation about, and is not responsible or liable for the accuracy or Pub. No. 10024108. Printed in U.S.A. April 2020. THE PINK PANTHERTM & ©1964-2020 reliability of data associated with particular uses of any product described herein. Metro-Goldwyn-Mayer Studios Inc. All Rights Reserved. The color PINK is a registered trademark of Owens Corning. ©2020 Owens Corning. All Rights Reserved. ----- page break ----- TB-10024108 TECHNICAL BULLETIN OWENS CORNING'S RECOMMENDATIONS AND DETAILS FOR INSTALLATION OF OPEN VALLEYS APRIL 3, 2020 ­ SUPERSEDES PREVIOUS BULLETINS Alternate method (If bleeder not installed) ­ No fasteners within 6 Self-adhered underlayment one with /one without the bleeder (side-by-side) of centerline underneath valley metal It is recommended to snap a chalk line 3 inches on either side Underlayment laps 6 Valley of the valley from top to bottom. Diverge an 1/8 inch per foot, over self-adhered centerline top to bottom. underlayment 6 Metal valley Install a 3 inch to 4 inch wide bed of ASTM D4586 roofing flashing cement along the chalk line. The bed of roofing cement should Chalk lines diverge 12" top lap be about 1/8 inch thick. Too much roofing cement can blister per foot the shingles. The roofing cement prevents water from washing 1 clipped off under the cut shingles, and provides wind resistance. Underlayment corner at 45° Install full shingles in a book like pattern, lining up the top Asphalt roof cement corners with the chalk line. Install with the standard nailing 2" to 3" wide, under pattern. Hold nails back at least 6 inches from the center cut side in blinded line. Make sure there is an offset greater than 4 inches on the seal fashion shingle below, and install with the standard nailing pattern. Hold nails back at least 6 inches from the centerline of End shingles trimmed to chalk line the valley. and set in 3 width of roofing cement The corners must be clipped. Cut the top point of each shingle one to two inches back at a 45 degree angle. Clipping the corners will allow water traveling down the valley to be deflected back into the valley. Note: This document supersedes any previous Owens Corning Technical Bulletin on this topic. Please contact 419-248-6557 for additional information. OWENS CORNING SCIENCE AND TECHNOLOGY, LLC Email: gettech@owenscorning.com ONE OWENS CORNING PARKWAY TOLEDO, OHIO 43659 Disclaimer of Liability 1-800-GET-PINK® Technical information contained herein is furnished without charge or obligation and is given and www.owenscorning.com accepted at recipient's sole risk. Because conditions of use may vary and are beyond our control, Owens Corning makes no representation about, and is not responsible or liable for the accuracy or Pub. No. 10024108. Printed in U.S.A. April 2020. THE PINK PANTHERTM & ©1964-2020 reliability of data associated with particular uses of any product described herein. Metro-Goldwyn-Mayer Studios Inc. All Rights Reserved. The color PINK is a registered trademark of Owens Corning. ©2020 Owens Corning. All Rights Reserved. ----- page break -----