Adding a second honey super

[Nyleve]

Bees have done well this very hot, dry spring and have filled the first honey super with nectar. There is some capped honey on the frames, but it's mostly nectar. Would it be better to wait until there's more capped honey before adding a second super or is it good to do it now so they have lots of room? Also, I've read different opinions about whether you put the new super under or on top of the partly filled one. I'm not sure I've ever had to deal with this issue so early in the season before. Thanks for advice.

[TheHoneyPump]

It is always best to add supers BEFORE the honey is being capped.  Open nectar and honey is movable and useable.  The bees can use it to draw comb and can move it to reorganize the nest adapting to the extra space.  Capped honey is fixed in place.  Once capped they dont touch it until they really need it.
Under super the added box.  Lift the existing box(es) and put the added space under it.

[Nyleve]

Thank you. I'll go hunt through my old frames right now and get an empty super on.

[cao]

I usually will add another super when they have the first one mostly full.  I don't want them running out of room to store the nectar while they are drying it.  If I plan on harvesting the mostly full honey super then I will add the new one below the full one.  It  makes it easier to remove the full one later when they have it capped.  If I plan on leaving the mostly full honey super for the bees then I will add the empty on top and see if they get it filled so I can harvest it later.

[Nyleve]

Done. Got my husband to help do the heavy lifting - boy that super was heavier than I expected. It made sense to me to put the new (empty) super below the full one because then I'll know when it's capped and ready to harvest. If I left it below the empty, I wouldn't be able to see how it was going. Thanks for the help.

[tycrnp]

I add my supers on top. I have some hives 5 supers tall and I just don't have the strength (or desire) to move all of them.