Addressing Common Mistakes with Two-Component Low-Rise Adhesives
July 23, 2019
Two-component low-rise urethane adhesives have become increasingly popular since their introduction into the single-ply roofing industry over 30 years ago. Since 2015, the two-component low-rise urethane adhesive market has significantly expanded due to the introduction of new low-pressure dispensing equipment.

While low-rise urethane adhesives provide several advantages when designing a roof to withstand extreme weather events, there are common mistakes that can affect the application of the product.

Below are common mistakes that can occur during two-component urethane adhesive applications:
  1. Gaps between the deck and wall/penetration that are not sealed: Unsealed gaps allow humid air to enter the roofing assembly and condensate on the deck, weakening the insulation facer. A physical air block using foam or a backer rod in addition to VapAir 725TR or Pressure-Sensitive Flashing is required.
  2. Loose material or moisture on the deck: Dirt, dust, debris, and loose felts will compromise the adhesive bond. After brooming, use a blower to remove any residual contamination. Deck must be dry.
  3. Un-weathered asphalt wasn’t primed: Carlisle requires the use of CAV-GRIP III or 702 Primer over weathered asphalt when beads are spaced at 4”, 6", or 12" o.c.. Adhesion to un-weathered asphalt is doubled with CAV-GRIP III or 702 Primer, with CAV-GRIP III being the preferred method. Fastening the first layer of insulation is an option.
  4. Depressions in the deck not accounted for: Hard insulation boards will bridge depressions or deflections in the deck. These areas should be marked ahead of time so that more adhesive or thicker adhesive can be applied to compensate.
  5. Pencil thin beads applied: Proper application and performance requires a minimum ½"-wide wet bead of adhesive that will foam out to around 1-1.5".
  6. Bead spacing exceeds specification: Bead spacing has a direct impact on the uplift performance of the assembly. If the spec calls for 6" o.c. and it is applied it at 8" or 9" o.c., the ultimate uplift strength will be reduced. A 4" o.c. spacing requires 12 beads per 4' x 4' board. A 6" o.c. spacing requires 8 beads per 4' x 4' board. A 12" o.c. spacing requires 4 beads per 4' x 4' board (Maximum 4' x 4' insulation boards when adhesive is extruded at 12" o.c. or when boards exceed 4" thickness, or 4' x 8' insulation boards when adhesive is applied in full spray, 4", or 6" beads.).
  7. 12" bead spacing used in corners and perimeters: Corners and perimeters experience more wind uplift pressure, which is why Carlisle requires tighter bead spacing in these areas. 12" bead spacing is not acceptable in corners or perimeters. Know the spacing requirements prior to starting the job.
  8. Thin application over gravel BUR: A thicker application of adhesive is required over a properly prepared gravel BUR. The foam must rise 3/8" above the remaining gravel, or it won’t touch the board.
  9. Not waiting for “string/gel” time: If insulation boards are set prior to the adhesive reaching string- or gel-like consistency, the foam cells collapse back to a liquid and the adhesive loses a significant amount of its holding power. This is very important to note.
  10. No weighted roller used, and no relief cuts or constant weight applied: Rigid insulation boards must be forced into the adhesive with a 150-lb. segmented weighted roller. Relief cuts and constant weight are sometimes required to promote a solid bond. Rolling the boards at the 5-minute mark allows adhesive to gain strength.
  11. Changing static mixing tips: When the Part-A side and Part-B side of 2-component urethane adhesives are mixed together, it creates a thermal reaction that produces the adhesive. The adhesive in small static mixing tips will begin to solidify after 15-20 seconds, meaning the tips must be changed to avoid off-ratio or clogged guns.
  12. Not shaking Dual Tanks: Dual Tanks use a propellant to disperse the adhesive. To activate the propellant, the tanks must be shaken for 30-seconds prior to using. When the tanks are not agitated, the adhesive will not disperse properly, reducing coverage rates or producing off ratio adhesive.
  13. Cold or Hot Adhesive: Keeping adhesive at the recommended temperatures is important to ensure proper performance. Adhesives that are too cold or too hot will affect coverage rates and the performance of the adhesive. During winter applications, hot boxes and heated blankets should be used to keep the material between 70-90°F.

For more information about two-component low-rise adhesives, please contact Austin Kulp.


    Austin Kulp
    Fleece Membranes & Coatings Product Manager
    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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