Gaps between frames can be a real problem with bee hives as they allow pests easier access.
Once your frames are together the bees will seal the inside join with their wax/resin mix. The bigger the gap the more work for the bees, the longer it takes them to secure the box and the higher the risk of pests during that time. Another issue can be water. While the bees may have sealed the inner join, water can run down the outside of the box and sit between the joins, even when you think the joins are perfect, they wont be waterproof. This could cause rot or fungus with Pine.
If you use a roller to paint the inner connecting surfaces the roughness of the painted finish can create an uneven surface and leave a gap when you place the frames together. One way to stop that happening is not to paint the surface at all, oil it, or wipe on a layer of paint with a sponge or cloth. This leaves a nice thin even layer that should leave minimal gap between the frames.
Below – Using Bees Wax to apply a thin layer of wax. This also helps stop the paint sticking….
Tip: Use Low Sheen paint for connecting surfaces to reduce them sticking together. Gloss paint tends to remain very sticky so the boxes will stick together, even after weeks of drying time.
When your frames are together place some tape along the joins to give the bees a chance to secure the box. You could remove the tape after a week. Leaving the tape on could also direct water in to the join…
and don’t forget a nice big roof to help keep the rain off….