# ventilation - "screened bottom board/dead air space configuration"



## Andrew Dewey (Aug 23, 2005)

In the most recent ABJ is a letter from John Hoffman talking about how he has successfully used a system to provide for dead air space on top of a SBB (Screened Bottom Board) with the hive on top. He claims to have kept the mites "at a comfortable low level" using this system. As he describes it, a box (shallow honey super) is placed over the SBB - the top of the box is covered by 1/2" x 1/2" wire mesh. He refers in his letter to a his September 2008 Bee Culture article "DEAD AIR SPACE - A Hive Configuration For All Seasons" I have not been able to locate the article yet to review it - but the basic concept is intriguing.

I'm interested in hearing other peoples' thoughts on the concept. Where I am on the Coast of Maine I've found it too damp to use standard SBBs and use regular wooden bottom boards, standard 10 frame hive bodies each having a 7/8" auger hole drilled mid way between the handle and the upper right corner of the box (facing the hive from the entrance), a notched inner cover and standard telescoping cover. Mr. Hoffman talks about not having any extra vents above the dead air space to avoid the "Chimney Effect." If I were to follow his method it would not be hard to plug the auger holes with corks - and the notch on the inner cover can be closed by making sure the telescoping cover is pushed up against it.

I imagine with his method the bees make use of the entrance in the SBB - it is unclear to me if he leaves the entrance open or reduces it - nor if it makes much difference.

How do people think his method might work in an area of high moisture? For example this last week we've had 4 days of heavy fog with temps in the high 50s/low 60s. A few (brave?) bees have been flying but most have been staying home. Today the temp is supposed to reach the 80s and it is humid, but without the fog. The bees will be flying today for sure!

If I were to test his configuration how many hives should I do it with (percentage) and what should I be looking for in terms of evaluating how well it works? I typically wrap my hives with roofing paper for winter - not so much to keep moisture out but wind. I had issues this past winter wrapping too well and trapping excessive moisture inside the colony.

TIA for your comments - and if anyone knows where I can get the September 2008 article I'd appreciate hearing about it.

I almost forgot - my motivations for being curious - I keep bees on two organic farms and so methods of mite control that don't call for anything that might put the farms' organic certification at risk is a good thing - And I'm trying to think about ventilation proactively before next winter so that more hives will make it through.


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## Charlie B (May 20, 2011)

I'm not sure I'm following Hoffman's SBB/Honey Super invention completely. I'm a visual person so I need a picture. I'm in coastal San Francisco near the ocean on a four story flat roof. We obviously get our share of fog, cold rain and constant high wind. The reason my hives are there is because we live directly across the street from Golden Gate Park so the girls have a lot to choose from in the way of flowers. I don't have a lot to chose from in where to place my hives but they are thriving on the roof.

The first thing I had to do is build a hive stand that wouldn't get blown off the roof and protected the hives. After I did that I noticed moisture build up immediately in the hives with using regular SSB's. I decided to make my own. I made a thicker SBB using a 2 1/2 inch
space between the bottom pull out drawer and the 1/8 inch mesh screen that's level at the entrance. (The bees walk on the mesh). I made the drawer to slide in during cold/fog spells and I slide it out when it's warmer. You can get sticky paper to line the top of the drawer to monitor mite infestation as well. The idea of the dead space was to dry up any moister. Also, between the drawer and the frame of the SBB there is a little gap, (otherwise, you couldn't get the drawer out) to still allow just a tiny bit of air in. 

It worked!! No moisture. That thicker space provided an adequate drying area. 

Charlie


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## jrbbees (Apr 4, 2010)

This get a bit confused. Mites or mosture?
A good 'non-chem' for mites is the drone comb freeze idea. If M Bush doesn't speak to this I would PM him. His experience is so valuable to all of us.


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## Charlie B (May 20, 2011)

I don't think SBB's are the only preventative measure for mite control. Freezing drone comb and powder sugar dusting are all good non-chem ways to reduce mite populations. SBB's help with both moisture and mites. I'm on MB's site almost daily. I loved his hive box jig and built a longer one to assemble five boxes at a time. Thanks Michael!!

Charlie, (I'm old too)


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## kbfarms (Jan 28, 2010)

We keep our SSB open all year, a slatted bottom board and use a screened inner cover, no mositure problems ever, girls do just fine. Easy to deal with.


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## Andrew Dewey (Aug 23, 2005)

Thanks for all the responses. Just to clarify for those who don't know me - I run about 30 colonies, currently none on SBB. If my understanding is correct, powdered sugar can only be used to knock mites down with a SBB. Is this correct? My efforts at getting bees to draw out the green plastic drone foundation (for freezing) has thus far been unsuccessful. With 30 colonies, "treatments" need to be efficient, and of course, effective.


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## johnblagg (May 15, 2011)

I myself wonder why a sbb could not be placed above a solid bottom board that was constructed to give a 6 inch space between it and the screened board and have a oil tray for mites to fall in ....might even help with shb at the same time?


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## bigevilgrape (Aug 21, 2008)

This is interesting. My dad and I where brainstorming plans for my next TBH and the design we decided on was a screened bottom board with a dead air space underneath with a removable bottom board. I didn't like how much light I was getting into the hive though the screened bottom board or how exposed it was to the wind in the winter.


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## Charlie B (May 20, 2011)

Andrew,

That's correct. Powder sugar dusting detaches varrora mites from the bees so they fall through the SBB to the sticky/oily bottom drawer board and so they can't get back up into the hive to re-attach to the bees. It's certainly not a "cure all" but it helps control mite population.

Other strategies like using 4.9 cell foundation or using just wax coated starter strips instead of foundation on frames also helps.

i wish you the best with your colonies.

Charlie


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## Andrew Dewey (Aug 23, 2005)

Thanks again for all the comments. As I have everything I need except for some hardware cloth and corks I think I will give it a try. I've got a colony started from a strong nuc, ready for its second box that I'll use for this experiment. If the weather cooperates I'll set the equipment up tomorrow and post pictures.


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## waynesgarden (Jan 3, 2009)

Hi Andrew. I'm not really understanding the idea of no ventilation holes above the dead air space. That seems like all the moisture in the brood and supers has to go downward to be expelled in the winter. Perhaps I'm missing something from the concept, but to me , a slight chimney effect is essential in moving warm, moist air up and out while drawing dry air in from below.

I'm running all hives with SBBs that I made from plans here (Thanks, Barry!) with the bottoms wide open from about the 1st of May this year and I'll close them up with slide-in luan closeoffs around October. I dust with powdered sugar every few week. When I dusted from above using a flour sifter, the SBB was key to getting the large amount of wasted sugar out of the hive. Now that I'm using a bellows duster, only a small fraction of the sugar gets in the hive but the SBB still helps keep the healthy mites that lose their grip from climbing back to the frames.

Wayne


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## Andrew Dewey (Aug 23, 2005)

Hi Wayne,

The no ventilation above the dead air space has me concerned for winter - but fortunately that is a few months away. And the lack of ventilation would go directly against what Tony has been telling us about successful wintering. I have observed that my strongest Russian colony is in two boxes without the auger holes. I'm not sure of the cause and effect there - meaning something else could be going on - but it makes me willing to experiment with the dead air space. On a side note, those Russians sure like their queen cups!


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## Andrew Dewey (Aug 23, 2005)

The deed is done. One very ready for a second box nuc placed over a Country Rubes SBB and an empty honey super. Now to watch and see what happens!

http://i38.photobucket.com/albums/e142/BeeBerryWoods/IMG_0484.jpg


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## judyv47954 (Jun 5, 2011)

I've been using some old double-screened bottom boards as a bottom board for the past few years. I haven't wrapped my hives in the winter, although I would like to get to it this winter. So, right now, my double hive bodies set on wooden bases built from scrap pieces of 2x12s. That leaves about a foot of dead air space between the bottom of the hive and the ground. I have yet to lose a hive since going to the screened bottoms.


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