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Open Mesh Floors





The case for the OMF


Features of the KISOMF






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KISOMF Floor (Keep It Simple OMF)


    Open Mesh Floors (OMF's) were originally developed as a tool for the monitoring and diagnosing of Varroa infestation levels within a colony.  Since then, beekeepers who have used them have enjoyed other benefits in addition to their original purpose.  I am one of these beekeepers and built my own OMF several years ago, the version I detail here has evolved from my original design to a point that I am satisfied with.  In particular I have avoided using a close fitting drawer arrangement which is prone to jamming particularly after or during the winter season.  These bees just love to propolise up these gaps and in this design there are no gaps to assist wax moth grubs to breed.  

    I use a simple spring arrangement that allows you to break the propolised seal by pressing down on a rear protrusion, and as the floor is at slight angle the line of propolis does not interfere with the withdrawal.  As a spin off, this construction lends itself to ease of securing and moving the hive and also isolates the colony from ground born damp.

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The Case for the Open Mesh Floor: 

    As an OMF keeps the hive very dry and ventilated the over wintering performance of the colony is improved and entrances can be kept reduced the whole year around.  Bees can defend a smaller entrance better and are less likely to get bad tempered due to robbing.  There is also much debate and research indicating that Varroa mites that naturally fall from the bees are permanently removed from their host by falling through the mesh.  Some research indicates that the better ventilation also increase the brood cycle timing and making the drone brood cells less optimal for raising Varroa.

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Features of the KISOMF design:

bulletEasy to manufacture, with no fiddly joint
bulletResistant to jamming by the bees gumming up sliding surfaces
bulletAllows easy strapping of hives for security or migration
bulletExcellent under hive ventilation, and isolation from damp ground

An example of well secured hives

This is a sad sight but demonstrates how useful it can be to have a ratchet tie-down strap around your colonies in apiaries prone to vandalism.  These hives are still together and came to to no harm despite this treatment.  As you can see the floors are actually an earlier version with round mesh vents .
Straps can be thread under the stand without lifting or disturbing the hive.

Although this article is about the OMF's, you may be interested in one detail of the roof design.  The roof has two pieces of timber about 40mm thick as part of the internal roof construction.  This allows good ventilation and the roof to sit square and level with the ratchet strap mechanism fitting into the gap.  Note that this design allows bees (or wasps) free access under the roof therefore the feeder hole cannot be left open, however with an OMF this form of additional ventilation is unnecessary.

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To break the any propolis seal that the bees might have built, press the rear extension of the OMF.  This compress the springs a further couple of millimeters to their full extent breaking any sticky binding.

The floor can then be easily withdrawn for maintenance or exchanged for a solid floor at the users preference.

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The construction is basically 4 pieces of timber glued and screwed together, with two aluminum runner strips being glued into a grove formed by a circular saw and using Bostic's 'No More Nails' or similar product.  

IMHO 'No More Nails' is an excellent compliant adhesive with a very junky name.  I have never yet had a strip come out.

Note that the uncompressed springs hold the OMF insert slightly higher than the stand until the brood box is placed on top.

Shown without the inspection board installed

Springs and things

Two special but simple springs need to be made.  This is very easy, I located a small local spring manufacture from our phone book, and bought from them sufficient spring wire for ten stands for about 3 ($5).   Simply bend the wire into the desired form and heat in a hot domestic oven for 20 minutes to harden.


A mesh from 2-3 mm hole size will be fine, plastic coated metal is best as plastic options tend to sag.   Bee suppliers will sell it for about 5/hive which is a bit greedy, shop around.



The mesh floor is constructed from one piece of 10mm five-ply, and the mesh is stapled to the underside.  The inspection board is a loose fit and also made from 10mm ply.   The timber batons on both  boards is actually door architrave (moulding  around a door opening).  This gives the run off slope for rain on the rear overhang.  The inspection board needs the baton to prevent bees from flying under the floor and onto the mesh underside.

A little Vaseline on the edges of the boards will ensure easy sliding removal after a long winter.

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Download Plans:

The following file is in Adobe Acrobat PDF format so  Adobe's (free) Acrobat viewer must be installed on your computer before this will work.  The plans have  no dimensions as this would only be of use for one style of hive, in my case the British National.  The actual dimensions are less critical than the principles of construction.  Good luck and let me know how you get on. 

Click here for the PDF format plans:  KISOMF2.pdf

If you require the free Acrobat viewer click here: GET ACROBAT VIEWER

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