approximately 60 square feet per gallon. Apply adhesive in smooth even coats, avoiding globs, puddles or other types of irregularities.
Once the adhesive has dried to the point of being tacky but will not string or produce adhesive legs with a light touch of a finger, the membrane shall be rolled onto the coated substrate being careful not to wrinkle the sheet or trap pockets of air. Once the membrane has been mated to the insulation/substrate, the membrane surface shall be thoroughly broomed with a stiff bristled push broom to ensure proper contact and 100% adhesion.
Care should be taken to ensure the TPO Bonding Adhesive is not applied to any membrane areas where seaming shall take place. All welding must be done to clean membrane.
Fully Adhered TPO Single Ply Membrane
Repeat this procedure for the second half of the sheet and each successive sheet of membrane on the roof, remembering to shingle all laps. Do not run any seams through field drains or sumps. Any seams running through drains shall be cut out and target patches (36" x 36") shall be installed.
The TPO Membrane shall be mechanically attached at the base of all parapet walls, walls, curbs, at all peaks, valleys and slope intersections where the net change in slope is greater than 1-1/2 inches per foot (12 inches).
Welding of Lap Areas
Roofing membrane is to be hot air welded only. Seaming "membrane to
membrane" and "flashing/detail membrane to membrane" shall only be done by hot air welding.
All surfaces to be welded shall be clean and dry.
Hot Air Welding
Machines for hot air welding are available from several different sources. Each manufacturer's instructions for use shall be followed, as well as all local codes regarding electric grounding, supply and other related functions. Since most automatic welding machines require 218 to 230 volts, the use of a portable generator on the roof is recommended for greater flexibility. Manufacturer requires the use of automatic welding machines for all field sheet seaming. Hand welding is only acceptable for flashings and those seams where the automatic welder cannot be used.
Hand-held welding equipment is also available to weld flashing membrane and areas that cannot be reached with the automatic welder. After the preheated nozzle tip is applied in the overlap area and the material starts to soften, immediately follow with a nylon hand roller to press the heated membrane surfaces together with slow, even movements. Keep the roller within one inch of the nozzle tip. Angle the hot air tool so that the flowing air faces the roller. Seam strength may be tested when cool. For best results, testing seams 8 hours after hot air welding is recommended.
Daily Welding Equipment Setup
The roofing contractor shall make sample test seams each day prior to welding field seams. The contractor shall, using scrap material, run at least two test seams, each a minimum of 2 feet long. Each test seam shall be used to determine adequate seam strength and to ensure the equipment has warmed up, is operating properly and proper settings have been determined. This should be done each time the equipment is turned