Re: Kelley Beekeeping top covers
That gap is probably there for a reason. It's been my experience when using solid wood tops to have expansion and contraction issues busting up the side rail joints. This expansion is worse across the grain than down the length. I've got quite a few cypress tops that are made up of t&g boards that have busted the joints and bent the top metal.
My tops that use engineered wood (plywood) don't have those issues.
I'm migrating to migratory tops and planning on trying to source HDO for that.
If those gaps bother you that much consider using a caulk with enough flexibility to move with the wood.
Georgia Wildlife Services, Inc