Other option would be leave wooden crownboard on for winter but that may comprise all the thermal properties of the polys...
Compromise to what extent? There should be no air leaks anywhere at the top of the hive and a well designed crown board would have a 40mm frame, across which the heat has to conduct. Any energy passing through the roof is still impeded by the thermal properties of the roof.
Compromise to what extent? There should be no air leaks anywhere at the top of the hive and a well designed crown board would have a 40mm frame, across which the heat has to conduct. Any energy passing through the roof is still impeded by the thermal properties of the roof.