inner cover explanation

[11nick]

Looking at inner covers from a website.  They offer three options.  One is screened, which is self-explanatory.  The other two are listed as shown below.  Can you tell me which is more customary?  They seem very similar to me, and I can't see where there is a distinct advantage in one over the other....
1. "Standard raised-panel style with 1/8" recess on one side and 3/8" on the other.  Corners are tenoned and plywood is 1/4" luann with the standard cutout in the center for a bee escape. "
2. "Heavy duty inner cover with fully-lapped corners and 3/8" plywood.  One side is completely flat while the other has a 3/8" recess.  Standard cutout in center for bee escape or ventilation.  Corners are glued when we assemble."

Thanks for your time.

[Michael Bush]

The luan is 1/4" thick and holds up well, is light weight.  The 3/8" is stiffer and probably holds up a little better.  I would just buy some 1/2" CDX and make covers and forget the inner covers and the telescopic covers and save a lot of money.

http://www.bushfarms.com/beestopentrance.htm#make

[JWChesnut]

Unless the cover has a bee space recess, ants (and other insects) will move into the cover/inner cover space. 

  Adding the binding frame with beespace and an access hole, the bees will patrol the space and keep ants away.  There may be a little bit of bur comb built in the 3/8th space, but not enough to worry much about.  Using a small recess on the super side prevents a lot of bridging and bur but does crush as many bees when replacing the cover.  Leaves a 1/8 + 1/8th = 1/4 space on top of the frames.

[11nick]

Unless the cover has a bee space recess, ants (and other insects) will move into the cover/inner cover space. 

Looking again at the descriptions of the inner covers in my original post, #2 should only be used if the 3/8" bee space side is down?

Can someone please explain the use of inner covers as the seasons change?  Isn't one side supposed to go up in the summer and the other side goes up in the winter?  (sorry if that's a dumb question)  Which side is which?  And, of the two inner covers listed in my original post, which one is the better to have?

Thanks

[Michael Bush]

Beekeepers have opinions and so do the manufacturers...

But a typical Langstroth box has 1/4" bee space (minimum beespace) at the top and 1/8" space at the bottom.  So a flat cover, in theory has a beespace.  In actuality through the buildup of propolis ect, that shrinks over time.  If you put an inner cover on that has 3/8" space it will make a total that is 1/4" over max beespace.  They both seem wrong.  Ideally you'd add 1/8" beespace at the top for maximum beespace which would then shrink over time from propolis.

Yes, some people put the gap down in winter and up in summer.  Some run it the same all year.