Plastic Welding on Flat and Pitched Roofs

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Roofers attach great importance to the quality and reliability of their welding machines when welding sealing sheets on flat and pitched roofs. For decades, Leister has been synonymous with reliable, durable and innovative products as well as an outstanding all-round service.

The Four Requirements for a Utility Roof

  • It should be permanently sealed to provide protection against external influences.
  • It should be planted with vegetation to enable retention, hold water and provide relief for the storm sewer system.
  • A photovoltaic system and a hot water generation system should be installed in order to generate a return.
  • The vegetation is intended to create biodiversity and improve the microclimate in order to give the roof area back to nature.

Under the right conditions, flat roofs offer a great opportunity to transform protective roofs into utility roofs. These days, building owners no longer have to choose between photovoltaic systems and green roofs, as a combination of both is particularly beneficial.

Safe Welding of Roof Sealing Sheets

Due to the increased requirements and multiple uses, a permanently watertight flat roof is essential. It is therefore particularly important to use good quality welding equipment.

The VARIMAT 700, VARIMAT 500 and UNIROOF 700 automatic welding machines from Leister are equipped with the Leister Quality System (LQS), Power Management and Monitored Welding Assistant for quality assurance.

Product overview of flat roof welding machines

Quality Assurance with LQS Roofing

With LQS Roofing, professional welding protocols can be created digitally in no time. LQS Roofing is available free of charge in the myLeister app for LQS-enabled Leister devices. With public projects and invitations to bid from architects, welding data logs are increasingly required. LQS Roofing supports the verification of welding work. This gives roofers investment security and equips them for the future.

Electronic quality assurance saves and logs welding work and offers the following benefits:

  • Verification with GPS-supported welding parameters
  • Automatic welding report for checking and minimizing possible errors
  • Verification document of the set welding parameters
  • Process safety with documented weld seam length
  • More control over the joining technique and prevailing electrical voltage
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  • LT_Varimat700_AP_12305.jpg

Welding Even with Undervoltage

Roofers struggle with undervoltage on construction sites all over the world. This is usually due to overloaded temporary construction site power supplies and faulty extension cables. Leister welding machines with power management and controlled electronics provide a solution.

Power Management

When using the Leister VARIMAT 700, VARIMAT 500 and UNIROOF 700 welding machines, you will achieve the required welding temperature even with undervoltage up to a maximum of 20%. The reason: Leister Power Management.

At an undervoltage of more than 20%, the Leister automatic welders switch off automatically, however. This is because the set welding parameters may then no longer be maintained, which impairs the welding quality.

The Right Extension Cables are Crucial

The full performance of electric welding equipment can only be achieved with the right extension cables. The following points should be noted:

  • the larger the cable cross-section, the better
  • always use reliable plugs and couplings
  • use high-quality extension cables
  • circuit breakers should be designed for 230 V, 20 a and for 400 V, 16 A
  • observe maximum cable lengths
  • use a generator with at least 10 kW capacity (rule of thumb: required power x 2)
  • a voltage of 400 V is advantageous for a reliable power supply

Cable Lengths at 230 V

Cable Lengths at 400 V

Welding with the Correct Parameters

Roofers want process safety when welding thermoplastic membranes. Leister’s “Monitored Welding” assistant monitors the welding process and sounds an alarm upon leaving the welding area.

To set the correct welding parameters, proven welding profiles can be found in the myLeister app and in the menus of the VARIMAT 700, VARIMAT 500 and UNIROOF 700 welding machines.

  • The average value (bold value in the table above) should be selected for the initial welding parameter in order to compensate for external influences on the building site. Sealing membranes made of PVC and FPO are the most widely used in the industry. A reminder: The welding parameters recommended by the material manufacturer must always be taken into account.

The average value (bold value in the table above) should be selected for the initial welding parameter in order to compensate for external influences on the building site. Sealing membranes made of PVC and FPO are the most widely used in the industry. A reminder: The welding parameters recommended by the material manufacturer must always be taken into account.

The Benefits of the Leister VARIMAT 700, VARIMAT 500 and UNIROOF 700 Roof Welding Machines at a Glance

  • Top-quality welding – always at the cutting edge of technology, customized to your needs and applications
  • Constant welding, even when dealing with undervoltage and difficult construction site conditions thanks to controlled parameters and power management
  • Quality assurance thanks to LQS Roofing (GPS welding protocol) and the Monitored Welding Assistant
  • High welding speed and reliable weld width
  • Welding window for determining welding parameters
  • Machines with intuitive operation and large displays
  • Low maintenance costs thanks to brushless motors and the use of high-quality components as well as long heating element service life
  • Long spare parts guarantee and highly-skilled service
  • Energy-saving Eco-Mode