Re: How to insulate a top bar hive for winter
My top bar hives do fine in our winters without any insulation - just the wood structure with its rainproof lid. I believe our winters are similar to Raleigh, my temperature extremes may average perhaps 5 degrees colder than yours.
I suggest that you make sure that the tarp does not impede hive ventilation. Condensation dripping on the cluster can be deadly. My TBHs all have top entrances.
--- Victor Hugo - "Common sense is in spite of, not the result of, education.”