TPO and PVC Welding Guidelines
July 22, 2019
Cold welds are a major concern for any thermoplastic roofing installer. But following a few basic guidelines can go a long way toward ensuring good, long-lasting welds on TPO, PVC, and KEE HP membranes. In this post, we’ll discuss a few best practices that reduce the chances of cold welds and help ensure the watertight integrity of TPO, PVC, and KEE HP single-ply roof systems.

1. Appropriate Equipment
Use proper power sources or commercial-grade generators. Generators should be rated for 3,000 watts for two hand welders, or 6,500 watts for one auto-welder. Proper extension cords are critical. For auto-welders, use a 10-gauge wire with a maximum length of 100 feet; for hand welders, use a 12-gauge wire with a maximum length of 100 feet. Welders should be in good shape, with clean air screens and a clean nozzle.

2. Proper Temperatures
The following are starting guidelines for temperature, speed, and airflow. Settings may vary depending on membrane thickness (45-, 50-, 60-, or 80-mil).

Leister Varimat
Temp
Speed
Airflow
TPO
1004°F
12.5 ft/min
100%
PVC & KEE HP
1094°F
8.5 ft/min
100%

Leister V2   Temp  Speed Airflow
TPO
986°F 18 ft/min 90%
PVC & KEE HP
1094°F 10.4 ft/min 75%

BAK LarOn Temp Speed  Airflow 
TPO
1004°F 12.5 ft/min 100%
PVC & KEE HP 1094°F 8.5 ft/min 100%

3. Critical Welding Steps

Keep in mind that ambient temperatures will affect welding temperatures and speeds, as will welding in the sun versus welding in the shade. Certain substrates can hold heat in the membrane (polyiso insulation), while others can rob the heat from the membrane (concrete). When hand welding, immediately roll across the hot seam at a 45° angle with a 2” silicone roller. This helps to ensure the top membrane is adequately pressed into the bottom membrane. When welding across a step-off, be sure to crease the top membrane into the step-off with a 2” silicone roller immediately after welding. This will help prevent a water channel from forming in the weld. It’s important to perform test welds several times each day because of changing ambient and membrane temperatures. Simply cut a 1”-wide strip across the weld and peel to inspect the weld area. Remember to probe all seams at the end of each work day.

4. Cleaning and Maintenance

Always clean aged or dirty membrane before welding. On PVC or KEE HP, use PVC and KEE HP Membrane Cleaner; on TPO, use Weathered Membrane Cleaner. Clean all residue from the weld area and allow it to dry before welding. Maintain your equipment before, during, and after welding. Regularly inspect the silicone pressure wheels on your auto-welder and hand roller to make sure they’re not affecting the integrity of the membrane while welding or rolling. Clean the char off the heat gun nozzle using a brass wire brush and keep the intake free of debris to allow maximum airflow. On the auto-welder, adjust the nozzle to eliminate heel drag.
Following these helpful hints will ensure a better installation with fewer cold welds. If you have questions, check out Versico’s TPO and PVC Welding Guides or contact your Field Service Representative.

TPO Welding Guide
PVC Welding Guide 



    John Greko
    PVC Product Manager
    Product Marketing
    john.greko@carlisleccm.com

February 20, 2020
Code-Required Minimum R-Values

Over the past 10 years, there has been a shift in minimum required R-values. The 2015 International Energy Conservation Code (IECC) is the driving force behind this movement. More than 20 states have adopted the 2015 IECC, or a portion of its provisions, as their statewide energy code. See the chart below for minimum R-values per climate zone. Since 2009, the roofing industry has seen an R-10 increase in the majority of the states. The total minimum insulation thickness has increased from 3.5" (R-20) to 5.2" (R-30) in parts of over 40 states. The map below can help you identify climate zones within your state. Climate zones 4 through 8 have experienced an R-10 increase. Additional resources are provided below to help you determine the applicable energy code and its associated minimum R-value requirements in a given state or local jurisdiction.    1. Minimum Insulation R-value Requirements: Non-Residential, Above Roof Deck    2. The Building Codes Assistance Project For more information on R-value requirements, please contact Brandon Reynolds at brandon.reynolds@carlisleccm.com

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February 6, 2020
Polyiso Storage, Handling, and Application Guidelines

It is well known that moisture is detrimental to roof system performance. Wet insulation can lead to several issues including mold, reduced membrane adhesion, and ultimately roof system failure during wind events. Because wet polyiso must be removed and replaced, watertight tie-ins are essential every night. But let's take a step backwards and look at overall polyiso storage before and during installation. An appropriate understanding of storage, handling, and application will result in a properly constructed roof system. Material delivery should be carefully coordinated with the roof installation schedule to minimize outdoor storage. However, short-term outdoor storage can be necessary at times. When storing polyiso outdoors, bundles should not be stored directly on the ground. If possible, they should be stored over a finished surface rather than dirt or grass. Bundles should be covered with a waterproof cover and secured to prevent wind displacement. Exercise care when handling polyiso to prevent breaking or crushing the edges and surfaces. Polyiso should always be installed on dry roof decks and in dry conditions. Apply only as much polyiso as can be covered by completed roofing the same day. Roof surface protection (plywood) should be used in areas where storage and staging are planned to reduce direct, excessive traffic. Tips: Place bundles on pallets or included feet over a finished surface such as gravel, pavement, or concrete. Remove polyiso bundles from trucks with proper equipment. Do not push bundles off the edge of a truck or "roll" a pallet across the roof deck. Follow Versico's requirements regarding product application to ensure adequate performance of the roofing system. For more information, please contact your sales representative.

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January 23, 2020
CAV-GRIP 3V 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. Versico's focus on innovation has resulted in new products that make cold weather installations more manageable. One product leading the pack is CAV-GRIP® 3V 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 3V in cold weather. Here is some advice to live by: STORAGE: Whether at a distributor's shop or on the jobsite, CAV-GRIP 3V 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 3V 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     ryan.ferguson@carlisleccm.com

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