Welding TPO and PVC Coated Metal
June 25, 2019
Welding Carlisle’s coated metal is quick and easy if you follow a few simple guidelines. Here are some useful tips for your next Sure-Weld® TPO or Sure-Flex™ PVC Coated Metal installation.

Product facts 
Description: 24-gauge hot-dipped G90 galvanized steel sheeting with a layer of 35-mil non-reinforced TPO or PVC flashing laminated to one side
  • Size: 4’ by 10’
  • Packaging: 10 or 25 sheets per pallet
  • Standard colors:
    • TPO – White, Tan, Gray, Bronze, Patina Green, Rock Brown, Terra Cotta, Slate Gray
    • PVC – White, Tan, Gray
  • Markings: The underside of each coated metal sheet is marked with “TPO” or “PVC”; these markings are repeated several times to avoid misidentification
  • Shelf life: None
  • IMPORTANT: TPO and PVC are not interchangeable and will not weld to each other
Before you begin
It is essential that the material is clean. The flat sheet goes through a few processes at the contractor’s metal shop, including shearing and breaking. When the metal is formed, it picks up dirt and contaminants that can negatively affect its weldability. The most common error associated with hot-air welding coated metal is the lack of proper cleaning.
After the coated metal profiles are fastened into place on the roof and before you begin welding, clean with Weathered Membrane Cleaner (for TPO) or PVC and KEE HP Membrane Cleaner (for PVC and KEE HP). Pour the appropriate cleaner from a safety can onto an HP Splice Wipe or other natural fiber rag; then, wipe the metal with the wet cloth to make sure the entire area is clean. If there’s a heavy buildup of dirt, you may need to use a Primer Pad to remove it. When working with cleaners, remember to wear appropriate personal protective equipment, including safety glasses and permeation-resistant gloves that meet ANSI/ISEA 105-2005.
Make sure the underside of the membrane being welded to the coated metal is also cleaned. Allow at least 10 to 15 minutes for the solvents in the cleaner to flash off the surfaces you’ll be welding.

Heat welder setup
When setting up your heat welder, you must consider the thickness of the membrane you’re welding to the coated metal. An 80-mil membrane will require more heat than a 45- or 50-mil membrane. Start the process with the hand welder at the number 7 or 8 setting. Because the 35-mil TPO or PVC film is laminated to the metal, it remains robust during the welding process and will accept more heat without distortion.

Welding coated metal to membrane
Start the welding process by building an air dam parallel to the rear edge of the metal. This will trap the heat and ensure it isn’t lost under the membrane. Using a hand welder and a 2” neoprene roller, weld the membrane to the coated metal, then roll in a perpendicular motion.

Check your welds
To check for proper fusion, weld a strip of membrane to a scrap piece of coated metal. Once your weld has cooled, pull the membrane until failure. Proper fusion has occurred if the membrane delaminates from itself, leaving the bottom ply welded to the film, or if the membrane tears when you try to pull it off the coated metal.

For more information on securement requirements and instructions on how to address metal end joints, follow detail U-1B. Please contact Jim Gage with questions.

    Jim Gage
    Senior Technical Specialist
    Product Marketing
    [email protected]
January 14, 2020
CAV-GRIP III in Cold Weather: Best Practices

As mother nature's cold hands grip much of the continent, many roofing contractors are forced close up shop until winter surrenders to spring. For many contractors, the onset of cold weather means delayed progress, but that mentality is changing. Carlisle's focus on innovation has resulted in new products that make cold weather installations more manageable. One product leading the pack is CAV-GRIP® III Low-VOC Adhesive, which can be installed in temperatures as low as 25°F (-4°C)! Like other adhesives, there are guidelines to follow when using CAV-GRIP III in cold weather. Here is some advice to live by: STORAGE: Whether at a distributor's shop or on the jobsite, CAV-GRIP III should ALWAYS be stored in protected, heated spaces with the temperature maintained above 70°F (21°C). Adhesive can thicken or gel when exposed to colder temperatures for an extended period. When reheating with a heated blanket or hot box, it can take hours to thoroughly heat the contents and re-liquify. It is recommended to reheat for 12-24 hours prior to use. If the spray gun is spitting, sputtering, or clogging, it is a good indication you've got cold material. GUARD AGAINST HEAT SINKS: A "heat sink" is a material or surface that absorbs heat from surrounding objects. Place cylinders on insulation to avoid direct contact with a cold steel or concrete decks. These surfaces will act as a heat sink, rapidly cooling the cylinders. HOT BOXES AND HEAT BLANKETS: Shop-fabricated or manufactured hot boxes and heated blankets are required to keep CAV-GRIP III above 70°F (21°C) when working in colder temperatures. Do not use band heaters due to risks associated with overheating a pressurized cylinder. Devising a way to insulate and heat the hoses also aids in keeping the adhesive warm and spraying properly. Removing cylinders from the cardboard box will aid in heat transfer. ROTATION: It's a good idea to preheat cylinders to 90°F (32°C) as a safety factor against wind chill. Rotate cold tanks into a hot box and replace with heated cylinders. SHAKE CYLINDERS TO AGITATE CONTENTS: Shaking cylinders is a good way to avoid settling of contents and to maintain spray pressure. SPRAYING ISSUES OR GUN CLOGGING: If the spray tip begins to spit, sputter, or clog entirely, there are two main culprits: 1. COLD MATERIAL - Clean the gun and hose from the problem cylinder with Low-VOC UN-TACK prior to attaching to a new, warm cylinder after it has been shaken. 2. CLOGGED SPRAY TIP - If spraying stops, remove the brass spray tip and spray the adhesive into a garbage bag. If the adhesive flows through the wand in a straight stream with no hesitation, then the tank is still functional (assuming it's warm). Simply clean or replace the brass tip and begin spraying again. For more information, please contact your regional manager.     Ryan Ferguson     EPDM Product Specialist     Product Marketing     [email protected]

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December 23, 2019
Installation Tips for Pressure-Sensitive Elastoform Products

STORAGE: Heat exposure is what causes Pressure-Sensitive Elastoform Flashing® (PSEF) to cure on the roof after installation, so storing all your PSEF in a cool place will maximize its shelf life. Carlisle performed an experiment where Sure-White® Corners were refrigerated for 18 months and they were still uncured and usable. Pretty "cool" for a product with a 6-month shelf life! HEAT: Want to make your PSEF easy to work with? Use a heat gun to warm the flashing prior to installation in colder weather. Always heat Sure-White PSEF even in the warmer months. Rule of thumb; store cool and install warm! INSTALLATION: Speaking of forming corners, the PSEF stretches and forms better when the elongated diamond pattern is installed parallel to the deck membrane. Additionally, it helps to use the poly film as a separator when folding the corner in half to prevent the exposed tape edges from sticking to each other. POURABLE SEALER POCKETS: One of the biggest mistakes Carlisle encounters with Pourable Sealer Pockets is improperly applied or missing primer. It is very important to prime the flashing that is turned down into the pocket, as well as the flashing on the top rim of the pocket. Primer is necessary to achieve a long-term bond between Pourable Sealer and PSEF. If separation is present, it's likely that primer application was missed. It is also important and necessary to thoroughly clean and prime penetrations prior to filling pockets with pourable sealer. OUTSIDE CORNERS: Double-wrapping outside corners is a great idea on ballasted systems, especially if the base membrane isn't cut perfectly tight to the curb. PSEF needs to have a solid surface beneath it for long-term performance. If an additional layer of PSEF is installed to eliminate voids at outside corners, the corner flashing will be better able to withstand movement from expansion/contraction forces and will be less likely to develop a hole than if a single layer of PSEF is used. LAP SEALANT: All PSEF requires Lap Sealant to be applied and feathered over the entire splice edge. Please contact your Regional Manager with questions     Ron Goodman     EPDM Product Manager     Product Marketing     [email protected]

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November 26, 2019
Seam Probing

Seam probing is an important final step in the hot air welding process because it is a good indicator to determine if proper fusion has occurred between the membrane layers. Whether the membrane is TPO or PVC, both products need to be probed – but with slightly different techniques. Probing must be done once hot air welds have thoroughly cooled (at least 20 minutes). Premature probing can damage warm seams. Hot air welded seams must be probed throughout the day to check seam quality and to make proper adjustments to hot air welding equipment. The repair of deficiencies must be done routinely throughout the day, but no later than the end of each workday. A blunt or dull cotter pin puller is an acceptable tool to perform the probing task. Carlisle offers a custom-designed Seam Probe that incorporates an ergonomic, threaded handle with a heat-treated, plated steel tip. With continued use these tools will wear down, creating a tip that is too sharp for probing. Blunting the tip is necessary when this occurs. When a substantial amount of probing is necessary, an extension pole can be threaded into the handle of the Carlisle probe. This allows the operator to stand up while probing long runs of field seams. Getting started: Draw your probing tool tip along the edge of the heat welded seam. Apply firm pressure to probe the seam junction, but not into the bottom membrane sheet. The tool will not penetrate into the lap area of a properly welded seam. If the seam probing tool penetrates into the welded overlap area, use a water-soluble marker to mark the beginning and the end of voids or wrinkles in the seam edge. Repair seam deficiencies as soon as possible using the hand held welder. Carlisle recommends that repairs be made the same day deficiencies are discovered. Probe repaired seams after they have cooled completely. If the repair is acceptable, wipe off the water-soluble marker lines; if not acceptable, repair the seam using standard heat welded overlay procedures. Another reason all laps must be probed each day soon after they have cooled is to verify the welder set-up is effective. Particular attention must be given to all membrane intersections and heat welded seams at insulation joints. In addition, there should be periodic checks (including at the start of each day) to verify good peel strength. Considerations when probing TPO systems: TPO does not "flow" like PVC. If you observe an area in which you see "flow" of the bottom ply, scorched areas of detail/flashing membrane, or scorched field membrane welds, these areas should be probed. If these areas are overheated to the point of membrane damage, an overlay repair will be required even if the weld probes successfully. A properly heated field membrane weld will typically have a visual "sheen" approximately 1/2" wide on the bottom sheet at the weld overlap. When walking seams, look for the sheen. If it is not present, probe to ensure weld quality. TPO seams require a minimum 1.5" weld. Welds less than 1.5" must be overlaid as stated in Carlisle’s specifications and details, even if probing does not produce deficiencies. Considerations when probing PVC systems: Welds on PVC systems should produce "bleed out". Bleed out refers to the flow of the bottom ply (of the top sheet) outside of the weld. If you do not see bleed out at seam areas, this increases the probability the seam did not receive enough heat when it was welded. Be sure to probe these areas to ensure weld quality. PVC is a “softer” and more flexible membrane than TPO. As such, a different probe should be used than the one used on TPO roofing systems. The PVC probe should have a blunt/dull tip, or utilize a "hook" screwdriver with a flat head. PVC seams require a minimum 1.5" weld. If you observe welds which are less than 1.5", these should be overlaid following specifications and details, even if probing does not produce deficiencies. Remember, application of Cut Edge Sealant should not begin until all probing is completed. Please contact Jim Gage with questions.     Jim Gage     Senior Technical Specialist     Product Marketing     [email protected]

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