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• <br /> KP Roof Repairs and Roof Improvements Project Section 07500 <br /> Community Transit, ITB#2019-028 Single Ply Membrane <br /> 4. Apply manufacturer cut edge sealant to all cut edges of sheet membrane. <br /> 5. Repair tears, voids, and lapped seams in roofing membrane that do not meet minimum <br /> requirements. <br /> 3.12 HOT-AIR WELDING OF SEAM OVERLAPS <br /> A. General <br /> 1. All seams shall be hot-air welded. Seam overlaps should be 5-1/2 inches (140 <br /> mm)wide unless otherwise noted. <br /> 2. Welding equipment shall be provided by or approved by the manufacturer. All <br /> mechanics intending to use the equipment shall have successfully completed a <br /> training course provided by the manufacturer prior to welding. <br /> 3. All membrane to be welded shall be clean and dry. <br /> B. Hand-Welding: Hand-welded seams shall be completed in two stages. Hot-air <br /> welding equipment shall be allowed to warm up for at least one minute prior to <br /> welding. <br /> 1. The back edge of the seam shall be welded with a narrow but continuous weld to <br /> prevent loss of hot air during the final welding. <br /> 2. The nozzle shall be inserted into the seam at a 45 degree angle to the edge of <br /> the membrane. Once the proper welding temperature has been reached and the <br /> membrane begins to "flow," the hand roller is positioned perpendicular to the <br /> nozzle and rolled lightly. For straight seams, the 1-1/2 inch (40 mm)wide nozzle <br /> is recommended for use. For corners and compound connections, the 3/4 inch <br /> (20 mm)wide nozzle shall be used. <br /> C. Quality Control of Welded Seams <br /> 1. The Applicator shall check all welded seams for continuity using a rounded <br /> screwdriver. Visible evidence that welding is proceeding correctly is smoke <br /> during the welding operation, shiny membrane surfaces, and an uninterrupted <br /> flow of dark grey material from the underside of the top membrane. On-site <br /> evaluation of welded seams shall be made daily by the Applicator at locations as <br /> directed by the Owner's Representative or manufacturer's representative. <br /> Correct welds displaying failure from shearing of the membrane prior to <br /> separation of the weld. Each test cut shall be patched by the Applicator at no <br /> extra cost to the Owner. <br /> D. Note: Manufacturers membrane welding requirements shall govern if in conflict with the <br /> specifications. <br /> 3.13 BASEFLASHING INSTALLATION <br /> A. Install sheet fleshings and preformed flashing accessories and adhere to substrates <br /> according to membrane roofing system manufacturer's written instructions. <br /> B. Apply approved bonding adhesive to substrate and underside of sheet flashing at required <br /> rate and allow to partially dry. Do not apply bonding adhesive to seam area of flashing. <br /> C. Flash penetrations and field-formed inside and outside corners with preformed manufacturer <br /> fleshings. <br /> Construction Documents6/0 <br /> 07500-11 <br />