If your hive style has an entrance where there is an internal obstruction between the landing board and the brood chamber, the brood chamber can usually be tipped back to meet the hive entrance requirements. Wedges can be used to hold the brood chamber in place. Because the floor directly under the brood chamber is not solid (often slats), there may be a decrease in efficacy.
For hives with floors with permanently reduced entrances the second brood chamber can be set back by 1/2 inch or 1.3mm to create an entrance the full width of the hive during the treatment period.
It is recommended to place an empty honey super on the hive to give the bees room to expand the cluster. There is no loss in efficacy. It is also recommended when treating in late summer and early autumn, to treat while the last honey super is still in place.
If a bottom board has brood chamber support rims that are less than the minimum height, shims (tapered wedges) can be inserted under the lower front corners of the brood chamber to increase the entrance opening to a minimum height to comply with the label.