Screened bottom board or solid?

[beeghost]

I think its location based, period. Where I am at in CA we had temps in the high teens/low twenties last winter, but hovered around the 30's as lows. I have a ventilated inner cover and a SBB that was left uncovered all winter..............not a single loss of a hive. They also didnt burn through their stores..............of course Eucalyptus bloomed in january and the temps were foragable, so that was great!!

Although I like SBB, im going to solid two hive pallets for ease and moving to migratory covers as well.

[Finski]

.
Winter in California!!! No losses

This picture is from 65°58′00″N, 29°11′00″E.
Folks have there beehives.

But honestly, it is an unfriendly place to bees
forecast: http://www.foreca.fi/Finland/Kuusamo

Anchorage Alaska....wow...getting worse
http://www.foreca.fi/United_States/Alaska/Anchorage

[wildforager]

I overwintered my 5 hives on screened bottoms last winter and didn't loose any. I did stack some straw bales around the hives and left the fronts open for solar gain. Yea we had a mild winter but this is the best I've done with overwintering in 3 years of beekeeping.