Trent Cotney, CEO, Cotney Construction Law
Thermoplastic polyolefin (TPO) is a well-known single-ply roofing system used in low slope roofing. These membranes are used for mechanically attached, adhered and induction-welded roofing systems. Over the years, we have seen a variety of warranty claims and Chapter 558 pre-suit notices related to seam welding. This article will briefly explore these issues.
Welding seams at the correct temperature is paramount. In the event that you have concerns over the adhesion of the seams, you should perform several test welds to ensure the welder is properly calibrated. The goal is to avoid excessive heat that destroys the polymer stabilizers in the TPO and leads to premature membrane deterioration. Conversely, if the weld is too cold, it may appear functional when probed but will detach over time, thereby allowing water infiltration. Test welds will help ensure that you have the proper temperature to avoid weld failure.
Another factor worth noting is what we refer to as welder drag – a condition caused by the improper alignment of the inside edge of the nozzle with the edge of the roller. Welder drag may cause improper alignment of the hot-air nozzle resulting in gouges in
the membrane outside of the seam. These gouges may lead to premature failure of the system.
Maintaining power to auto-welders requires the use of a generator with at least 10k-watt output. Avoid having other equipment run off this power source to ensure a steady flow of heat from the welder. Always check your manufacturer specifications before
starting the project to ensure you have the proper equipment needed to perform the work.
Watch out when using hand welders on prefabricated corners, boot and T-patches. Generally, these types of items tolerate lower temperatures. Hand welders that are not calibrated the same as automatic units tend to overheat areas. Finally, recognize that you
may have to weld patches or penetrations. Make sure to properly clean the area before welding to ensure adhesion.
From a legal perspective, in-field oversight and the documentation of existing and installation conditions help defend against claims of improper installation. Documenting the temperature setting, performing test welds at the beginning of the day, after lunch breaks and any time a machine is started also helps demonstrate proper calibration.
Contractually limiting workmanship warranties to not include punctures, shrinkage-related defects and wind speeds that exceed manufacturer specifications are just a few of the ways to mitigate your potential risk of ongoing warranty work. In addition, make sure that the specifications call out the right type of welder needed for the work to be performed – one that you have used and are comfortable using on the project.
Disclaimer: The information contained in this article is for general educational information only. This information does not constitute legal advice, is not intended to constitute legal advice, nor should it be relied upon as legal advice for your specific factual pattern or situation.
Trent Cotney is Board Certified in Construction Law by the Florida Bar, an advocate for the roofing industry and General Counsel of FRSA. For more information, contact the author at 866-303-5868 or go to www.cotneycl.com.
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