I was looking on MB site and he list 1 1/4 for brood and 1 1/2 for honey..... THe drawings I got from another site liste 1 3/8 (thats what i made all of them as I wasn't sure how many brood frames and how many honey, although I may change if it will help corall the queen in the brood. Watching some YOU TUBE videos some of those top bars looked as wide as 2".....I also noticed most did NOT have starter strips (didn't see any that did) and yet they built straight..... do they pick up the cracks and just know where to build? and is there an advatage to really wide top bars??