TPO and PVC Welding Guidelines
August 6, 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 Carlisle’s TPO and PVC Welding Guides or contact your Field Service Representative.

TPO Welding Guide
PVC/KEE HP Welding Guide



    John Greko
    PVC Product Manager
    Product Marketing
    john.greko@carlisleccm.com
                                                                                                                                                               
February 25, 2020
Dual Tanks Cold Weather Application Tips

Proper material temperatures are imperative to ensure that adhesive products deliver the highest level of performance. When applying adhesive products below the manufacturer’s recommended application temperatures, application speed and performance can be drastically affected. To help address material temperature issues, Carlisle has recently announced the availability of heated blankets and temperature sensing nozzle technology. Flexible FAST reaches its maximum performance when the material temperature at the time of installation is 70°F or rising. When temperatures fall below 70°F, urethane adhesives can experience mixture ratio issues that could create application issues. To help address material temperatures during winter applications, the use of hot boxes and power blankets are recommended to ensure the adhesive remains at 70°F or above at the time of application. For more information regarding heated blankets, click here or visit the website for one of Carlisle equipment partners: PowerBlanket 4C's Spray Equipment Panther East In addition to heated blankets, Carlisle has also made advancements to delivery systems to help applicators identify when an adhesive product is too cold. In January 2020, Carlisle introduced Temperature Warning Tips for Flexible FAST Dual Tanks. These tips make it easy to apply polyurethane adhesives properly. Carlisle’s Temperature Warning Tips provide the applicator with a visual cue to easily identify if the material is too cold during application: Nozzle turns BLUE when adhesive temperature is below the required 70°F. Nozzle will be CLEAR when adhesive is spraying at optimal temperature. Compression seal added to create a tighter fit between the gun and tip. This helps eliminate adhesive leaks. For more information, please contact your manufacturer's representative.

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February 11, 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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January 28, 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 Carlisle’s requirements regarding product application to ensure adequate performance of the roofing system. For more information, please contact your manufacturer's representative.

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