[also posted in the UK forum]
I'm currently making a prototype hive from very, very cheap Norwegian spruce flooring planks.
If I understand correctly, the planks are still fairly "wet" and will probably shrink a bit over the course of the year (the store where I bought them didn't say so, but I weighed the wood and consulted some tables, and one of the planks bled a little bit of sap at the one end). I would not be surprised to see the hive reduce 8% in height. Fortunately, the way the hive is designed, I expect the walls to shrink uniformly, and only in height.
What are your experiences with home-made hives made from cheap wood, specifically regarding shrinking?
The hive is 227 mm tall, and an 8% shrink would result in an 18 mm shrink. So I'm actually considering increasing the bottom bee-space by 18 mm, knowing that I'll have brace comb in the first year, until I can see what the boxes do, and then next year sand down the box to the design height. What do you think about that?