Many thanks for the replies. What about honey stores? My hive is a bit light since they are just coming off of the winter. Is there a certain amount of stored honey they should have in the 1st deep before adding a 2nd or is it only about the number of bees and the brood?
That is a very good question,
It is a good idea to add another brood box, in this case a second deep, when the bees have the bottom box 70 - 80 % filled out. Typically in your brood box, that will be mostly brood with some honey. The brood will be in the center most frames. Each individual brood frame will contain brood in the center of the frame. The outer portion of the frame may contain honey and/or pollen.
If the bees have solid frames of honey in the brood chamber, they will be the outer frames. If they start to run out of room in the brood chamber, they will start to "backfill" and make swarm preps.
HTH,
Shane