Thanks for the info. guys.
Both the 7/8 cedar and 3/4 pine which we get is planed both sides -
maybe someone in the past thought cedar needed to be thicker to make up
for strength.For a given outside hive dimension it does of course give
slightly smaller inside sizes but the bees seem to be able to live with
the smaller overall space i.e. there doesn't seem to be any more
tendency to propalise.
 
Happy honey hunting
Alan Riach