Question for roof plumbers

Posting here as I'm assuming that roof plumbers might know this. I'm renovating a period house and want to use metal down pipes for the stormwater which means that I'm going to have to make up some bends in the galv downpipe, I don't want to use pop rivets and silicon as this would not be in keeping with the period, which leaves only solder.
Question is are the joints straight butt joints with only the solder holding them together or are the joints cut with small tabs ( on the inside so they don't show) to give increased holding power through more surface area? The house currently has pvc downpipes so I can't take one apart to see.
Back when we used to make expansion chambers for our motorcycles we would cut the chamber at half the required bend angle and rotate one half 180deg then weld together for the complete bend, I'm assuming that this is how metal downpipes are done.


Read the full thread at RenovateForum.com...