Rubber Seal around Roof Vent

[LoterGarry]

It's windy at the moment and I found this rubber circular seal on the ground this morning. Worked out it was around the middle of a vent/flue on the roof for I guess the main stack inside the house. I've looked at my neighbours vents and none of them have this seal around them. so the question is was this seal doing anything I should now be concerned about. Like water ingress or the thing coming loose, plus having inspected the seal would it not have been better placed at the bottom of the vent rather than midway up. Seems strange though it would have worked it's way up a pipe if it was.

[OliverShultz]

I’d fit a new seal, since without it you can get rain blowing in or reduced airflow. I’ve secured mine with a small bead of exterior-safe adhesive to stop it lifting again.

[JasonByrne]

I’ve had good results with their heat‑resistant compounds, and using Flourosilicone made a big difference for parts exposed to fuel and oil. Flexion handled the custom formulation and molding for me, so I didn’t have to juggle multiple vendors. Their setups in Thailand and Vietnam kept lead times reasonable while still hitting the certifications I needed.