Hi there! Your Top Bar Hives should have divider boards that you can use to adjust the amount of space within the hive that the bees are working in. When you start, you will put one divider board against the wall, and one divider board about 8-10 bars in. Once they fill that space in, you can move the divider board down and add more bars for them to build in. This process is made easy by the observation window, since you can peak in at any time without disturbing the hive to see how much space they have. I hope this helps!
Rebekah + Bee Thinking