I will be replacing a section of gutter on a barn in a month and was wondering what the best method of joining the sections is. I will have limited ergonomics working in a lift about 27 ft off the ground, this will be about 40 ft length of gutter. I have 10-ft sections of galvanized steel gutter on order. My thinking is that I'm going to rivet the sections together, maybe overlap by 6 inches, use a liberal amount of silicone sealant. Resistance spot-welding or soldering seems to be common for galvanized steel gutters but no mention is ever made of the increased tendency for rust happening at the joints due to the zinc coating being blown away by the heat. Working with heat directly at the eve / roof-line is also a fire hazard. So any thoughts on this?
Solder is certainly the way to go for the best joints, but given that you are using galvanized steel, its also a bit of an overkill as that joint will outlast the rest of the gutter by a lot (unless you're painting it). Solder will not increase any rusting as it does not remove the galvanized coating. Spot welding or welding does and would.
Rivets and sealant on 1-2" overlap are sufficient, no need for 6". That's how its done on aluminum gutters, no need to reinvent the wheel.