Warped/bowed inner covers, masonite or plywood?

I believe the commercial covers I have are thin boards. I use 1/2" plywood to make mine, and they are considerably stronger than the commercial ones -- I use a 1 or 1 1/4" or so high rim and leave 1/8" offset for the plywood -- leaves enough space above the frames for the bees to move around and helps to keep from breaking the plywood out when prying the cover off. Very propolis happy bees here.

I quit buying commerical covers, we always break them after a couple years with our bees. No problems with warping, but if you are getting warped covers, make sure you don't have serious condensation problems or leaks -- we had fits with wet inner covers when we used the Kelley plastic molded outer covers. Tossed them a couple years ago, always had water standing on the inner cover in the winter and they crack through and leak in a few years. Aluminum flashing covered wooden outer covers will last decades and don't drip water all winter onto the inner cover.

Peter

I have found that making my own inner covers out of luan (a little less than 1/4" thick) is the way to go for me with no warping. I cut the luan the same size as the outside dimensions of the hive and staple/glue 1/4" rims all the way around on both sides of the luan. Then I cut a 2" hole in the center of the luan and leave a 1" slot in the rim for ventilation/upper entrance.

I suspect that your hive lacks ventilation because the moisture in the hive is swelling the wood on the hive side while the other side is dry. This will cause the wood to bow down. If the bees had a chance to propolise the whole surface when it was first put on the bowing wouldn't be as bad. If you could take the cover off for a while and dry it out you could rub wax on the inside surface and then take a torch and give it a quick flash so it absorbs into the wood. Then the moisture will condense and drip instead of soaking in. This time of year I would want to get that moisture out of the hive.

>Does masonite not warp or bow, or is it worse?

Masonite is worse.

I now use a top hive entrances so no inner cover at all. The girls keep going in and out so I guess they like it too.

I've built some inner covers out of luan with a 2" hole in the center. One of them warped down until it was touching the frames.

I put 4 small screws near the center with the heads sticking down 3/8". These will rest on a frame and give me my bee space.

The rest appear to be ok

Thanks a bunch for the input folks. I appreciate the help!

Wolfer said:

I've built some inner covers out of luan with a 2" hole in the center. One of them warped down until it was touching the frames.

I put 4 small screws near the center with the heads sticking down 3/8". These will rest on a frame and give me my bee space.

The rest appear to be ok

Click to expand...

The reason it warps is putting the piece of luan into a grooved rim or rabbeted rim, there is no room for expansion of the luan, it is trapped. That's why I put on the strips of wood for the rims separately, on just the top and bottom, not the edges, so that the luan can expand and contract easily.

If there is a higher moisture content on one side verse the other it will still bow like crazy.

jmgi said:

The reason it warps is putting the piece of luan into a grooved rim or rabbeted rim, there is no room for expansion of the luan, it is trapped. That's why I put on the strips of wood for the rims separately, on just the top and bottom, not the edges, so that the luan can expand and contract easily.

Click to expand...

Yep, same here.

Acebird said:

If there is a higher moisture content on one side verse the other it will still bow like crazy.

Click to expand...

Your're right, but not nearly as bad as when there is no room to expand at all for the luan or whatever other material you use for the inner cover.