Thanks for your insights. I used to have the attic blocked off with a flat rock. The bees had propolised the rock down too.
But the location of my hive makes ants a big worry.
The hive is located in the foothills of SA, in the middle of a 100 acre property of re-vegetated scrub. We have lots of ants, termites, and all sorts of insects. I have the hive stand in oil/water cans to stop the ants, but a few ants always manage to get onto the hive stand. It just takes one twig or blade of grass blown against it and they’re on it.
For example, while setting up my hive, I left the nuc box inside a clean, newly built shed, on a table overnight planning to transfer the bees to the new hive the next day. By the morning, there were 100’s of ants going after the nuc box.
I reckon if I get comb in the roof it will be a bonus, and provide the bees with some honey of their own, and will also provide insulation in the roof. It might be a bit inconvenient on inspections, but then inspections are all around inconvenient with a langstroth hive.
Having attic space that the bees cannot defend seems risky for my location. I guess an alternative for me could also be to change over to a flat roof…