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]
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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November 12, 2019
Benefits of Using Sure-White EPDM Accessories on TPO Systems

Carlisle SynTec Systems allows applicators to use several of its productivity-boosting Sure-White® EPDM Pressure-Sensitive accessories on Sure-Weld® TPO roofing systems with up to 20-year Total System Warranties. Sure-White Pressure-Sensitive (PS) accessories can provide substantial labor savings on projects with hard-to-flash penetrations and are ideal when using a generator and hand welder isn't practical. Regardless of which roof system is being installed, experienced roofers understand there is always a good chance of encountering hard-to-flash roof penetrations, or simply a high volume of penetrations. Determining the best way to flash these items in a productive manner while ensuring a long-term watertight seal can be a serious challenge. This is where Sure-White PS accessories come into play. Keep in mind your alternative EPDM flashing options for TPO systems: Run into a hard-to-flash penetration? Sure-White PS Elastoform Flashing® is an option to consider. This material is highly malleable and adapts easily to odd shapes and surfaces, making it ideal for flashing pipes, scuppers, and other irregularly shaped penetrations. Overwhelmed by hundreds of roof curbs? Boost productivity by flashing curbs with Sure-White PS Cured Flashing in conjunction with Sure-White pre-cut 7" x 9" Inside/Outside Corners. This is the fastest way to flash roof curbs and can reduce application time by up to 70% when compared to non-PS flashing options. Sure-White PS accessories are also a great option for repairs on TPO roofs when access to power is difficult or it isn't practical to use a generator and hand welder. Transporting generators, power cords, and welders to difficult-to-reach roof sections can be cumbersome and labor-intensive. This additional labor can be avoided by utilizing Sure-White PS accessories, since most of these materials will fit snugly into a backpack! If you’re interested in receiving a free trial of Sure-White flashing, please submit a request using this form. APPROVED PRODUCTS: Sure-White Pressure-Sensitive Molded Pipe Seal Sure-White Pressure-Sensitive Pourable Sealer Pocket  Sure-White Pressure-Sensitive Inside and Outside Corners Sure-White Pressure-Sensitive T-Joint Covers Sure-White Pressure-Sensitive Elastoform Flashing  Sure-White EPDM Wall and Curb Flashings      Ryan Ferguson     EPDM Product Specialist     Product Marketing     [email protected]

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October 1, 2019
Special Color TPO Accessories

As the demand for different colored roof membranes has grown, Carlisle introduced its TPO Color Palette with five new colors. In addition to standard white, gray, and tan, Carlisle’s TPO Color Palette now features Rock Brown, Slate Gray, Terra Cotta, Patina Green, and Medium Bronze. Projects that use special color membrane from the TPO Color Palette usually need flashings and accessories in the same color. Here, contractors have two choices, one of which is painting standard accessories to match the membrane. However, this is a great opportunity to use Carlisle’s custom TPO accessory program and avoid painting altogether. All Carlisle custom accessories are available in the five TPO Color Palette colors, as well as white, tan, and gray. Whether it’s a simple split pipe seal or a complex prefabricated curb wrap, Carlisle can make it in all eight TPO colors and get it to the job quickly. In addition to being available in eight colors, here are some other great advantages to using custom flashings from Carlisle: • Save time vs. field fabrication: Trying to field-fabricate flashings can be time-consuming work, even for the most skilled and experienced roofers. Using prefabricated flashings saves time. • No need for paint: There’s no need to prime and paint the accessories to match the membrane; just install and go. • Speed: Custom accessories can be fabricated and shipped within days, not weeks. • Quality: All of Carlisle’s custom TPO accessories carry the Certified Fabricated Accessory (CFA) stamp of approval, indicating they are eligible for coverage as part of the Carlisle Total Roofing System Warranty. Next time you have a project using Carlisle’s TPO Color Palette TPO, consider using custom accessories to make the job faster and easier to install. Sure-Weld TPO Special Color Painting Guide  Sure-Weld TPO Special Color Program  Custom Accessory Quote Request Form      Adam Burzynski     TPO Product Manager     Product Marketing     [email protected]

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