We got a leak that most likely came from around one of the vent pipes.
To work on the pipes close to the high end of the roof I figured safety came first. So I attached a safety line to the chimney (see above) and hooked it to my harness (see below).
It was a bit cold, about -5C, but fortunately there was no wind, so overall it was not too bad. However, the roof patch that I had kept warm in the hottest room in the house, the heater enclosure, got rather stiff within about an hour. I would have had to warm it up again if there was more patching to do.
As it was, it went fairly easy - though I was a bit sore from the effort for a few hours afterwards.
Low roof on the street side. The entry point.
Vent with a suspected leak.
Another vent, a sewage one I believe.
Chimney. I have decided to patch around them all, just for a good measure.
High roof on the backyard side. About 6 m worth of drop.
Lots of patch used.
Sun setting down soon. Time to clear off the roof. Enough fun for one day.