Community College of Allegheny County Pittsburgh, Pennsylvania
2022 Library Roofing Project
3. Using an approved automatic heat welding machine or handheld heat gun and steel roller, weld a continuous seam. Minimum width of welded lap shall be 1-1/2 inch when using an automatic welder. Hand welds shall be a minimum of 2-inches wide. Only approved Automatic Walker Welders shall be used to weld seams (see Hot Air Welder Equipment). 4. Special attention must be paid to areas where multiple layers of membrane (3 or more) come together (T-joints). a. If probing these areas reveals the presence of voids or cold welds on 45 mil membrane, install a 4-inch round field cut flashing membrane (unreinforced) to the formed T-joint. 5. Allow hot air welder to warm up. Insert the nozzle tip of the hot air welder into seam area. Move nozzle at a steady speed along the seam area, immediately applying pressure behind the air nozzle with a neoprene roller or weighted wheel to ensure positive contact of the heated roof membrane lap. 6. Test lap edges with probe to verify seam weld continuity. a. Verify field strength of seams a minimum of twice daily and repair seam sample areas. b. All welded seams must be manually checked for voids or seal deficiencies by probing the entire seam area with a dull cotter key extractor after the seam has cooled. Properly constructed laps will not separate at the lap
interface when tested. In addition, there must be destructive testing performed at the beginning of every workday and every time there is an interruption in the welding process (i.e. Power failure, welder shut down and job site conditions change). All deficiencies must be repaired. Repair tears, voids, and lapped seams in roofing membrane that does not meet requirements.
c.
3.08 GENERAL FLASHING REQUIREMENTS AND STRIPPING INSTALLATION
A. Install sheet flashings and preformed flashing accessories and adhere to substrates according to membrane roofing system manufacturer's written instructions.
B. All flashings shall be installed as shown on the detail drawings. All membrane flashings shall be installed concurrently with the roof membrane as the project progresses. No temporary flashings shall be allowed without prior written approval of the authorized Tremco agent. If any water is allowed to enter under the new roofing due to incomplete flashings, the affected area shall be removed and rep laced at subcontractor’s expense. C. Flashings shall not be applied over existing thru-wall flashings or weep holes. All flashings shall extend a minimum of 8-inches above roof level unless previously accepted by Owner’s representative and an authorized Trem co agent. All existing flashings shall be removed before applying a new flashing. Install flashings in a neat and uniform manner with a “rounding” of all exposed corners. Care should be taken to ensure that the flashing does not bridge where there is a change of direction.
07540-12 THERMOPLASTIC MEMBRANE ROOFING
February 2022
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