Roofer’s View Video: Hand Welding TPO HQ
This video is shot from the installer’s point of view to illustrate hand welding TPO. The contractor is using a hot air hand welder to fuse the TPO surfaces together. There are 3 things required for welding TPO; heat, speed, and pressure. The heat originates from the hot air coming out of the welder. The pressure is the downward force applied onto the overlapped TPO with the silicone roller as it is rolled perpendicularly across the seam and the path of the welder. The speed is the rate that the welder and roller are moved in relation to the sheet. The pressure on the roller will remain fairly constant, however the speed and heat are relative. A beginner will typically be slower, so the temperature setting on the hand welder should be lower. As the skill level increases, typically the speed will too, so the temperature setting must be higher.
When you are hand welding TPO, the goal is to have a 2” wide weld, either at the seam, or in the case of accessories just the outer 2” of the flange is required (although some technicians prefer to weld the entire flange).
After the membrane cools it is highly recommended to use a seam probe to test the weld. The tip of the probe will be pressed into the seam as if to separate them, then the probe should be pulled along the seam to ensure that the weld is intact. TPO can be either overheated or under heated producing a false weld. This is commonly referred to as a cold weld. It will appear to be attached, however the probe will enter the seam with little pressure upon inspection.
See more of these instructional installation videos on GAF’s video library section.