Top Bar Ventilation

13772 Views 37 Replies 14 Participants Last post by Wyldbee, May 19, 2010

Zonker

Discussion Starter · Mar 17, 2010

The more I read this forum the more it seems like moisture/ventilation is the TBH biggest problem.

In the building industry we divide climates into hot, cold and mixed and into dry or humid. (I live in the worst case scenario of mixed humid which gives me plenty of business). It seems to me that in any dry climate, hot or cold, it would be hard to go too far wrong. Bees cool themselves through evaporation, which works great in a dry climate, and cluster for warmth without the risk of condensation.

In a hot humid climate insulation would be pointless and you could not have too much ventilation. The classic jungle hut without any walls comes to mind. and now that I think about it jungle bees nest on open branches, so ...

The really tough situation is the cold or mixed humid climates. Evaporation has limited effectiveness and condensation is constant, and probably unavoidable, all winter.

In those climates the TBH has two disadvantages. Being shallow the bees are usually clustered near the top where condensation occurs and being wide the bees are less protected from drafts. (roughly equivalent to trying to stay warm by wearing damp clothes and taking shelter from the wind in a football stadium).

I'm trying to work out a better THB design for the cold/mixed humid situation. I'm playing with the idea of a sloped roof to encourage the condensation to run to the sides or maybe using some sort of absorbent layer above the bars that could dry to the exterior like attics in our houses. I'm also wondering how to eliminate drafts without restricting ventilation.

Comments? Suggestions? Ideas? I'm new at this so don't hesitate to point out that I'm a knucklehead. I'm also an avid wood worker so I probably tend towards overly complicated because its an excuse to cut wood, but any help/wisdom would be appreciated.

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buckbee

· #2 · Mar 17, 2010

Zonker said:
The more I read this forum the more it seems like moisture/ventilation is the TBH biggest problem.

It is a problem in ANY hive - not particular to the TBH.

It seems to me that in any dry climate, hot or cold, it would be hard to go too far wrong. Bees cool themselves through evaporation, which works great in a dry climate, and cluster for warmth without the risk of condensation.

I agree - in that sort of climate you may well have to provide water for bees.

In a hot humid climate insulation would be pointless

In that situation, you may need to keep excess heat OUT ratehr than in, to avoid meltdown - so insulation is still needed.

I'm trying to work out a better THB design for the cold/mixed humid situation. I'm playing with the idea of a sloped roof to encourage the condensation to run to the sides or maybe using some sort of absorbent layer above the bars that could dry to the exterior like attics in our houses. I'm also wondering how to eliminate drafts without restricting ventilation.

Condensation can be dealt with by having good insulation, that also absorbs moisture. Think permeable - like glass fibre loft insulation. I and others have successfully used the Warré-style condensation trap - a shallow box with a mesh floor, filled with wood shavings and sawdust - or some other naturally absorbent/insulating material.

The floor is where more thought needs to be applied, IMO. I have successfully over-wintered a colony in a TBH with no floor at all, through two cold (last one -11C) winters in a generally damp climate, and my ventilated floor colonies have always been better than closed floor.

Tubes arranged on a frame, with 3mm gaps have been used (I think in France) and this may be worth looking at.

I stand by my opinion - at least in my climate - top insulation, bottom ventilation is the way to go in a TBH - or any hive.

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Zonker

Discussion Starter · #3 · Mar 17, 2010

What do the tubes arranged on a frame, with 3mm gaps do? Do they extend through the roof?

buckbee

· #4 · Mar 18, 2010

Zonker said:
What do the tubes arranged on a frame, with 3mm gaps do? Do they extend through the roof?

Nope. Let's say the width of your floor opening, i.e. distance between lower edges of sloping sides, is 5 inches. The tubing (say, 25mm polythene) would be cut into 5 in lengths - enough of them to lay side-by-side to fill the length of the floor/gap.

Like this: | | | | | | | | | | | | | | | | | |

ANd you would put 3mm thick rubber bands around every other tube to provide spacing that would allow ventilation and mites to fall out, but not bees/wasps to get in.

This is not new - it has been done in France, but I haven't got time to go looking up the link right now.

Zonker

Discussion Starter · #5 · Mar 18, 2010

Oh, I see. A different sort of screened bottom. Sounds like a lot more work than using actual screen.

I thinking that an attic would address a lot of these problems. Insulation below the vented attic would keep the temperature down in the summer and if the insulation is absorbent could move moisture out of the hive during the winter without introducing drafts. I think newspaper would work perfectly. I can say authoritatively (having slept on the ground under some newspaper) that its a surprisingly great insulator and its free.

I think I'm going to build the hive so that I can check/swap the newspaper during the winter without bothering the bees.

buckbee

· #6 · Mar 18, 2010

Zonker said:
Oh, I see. A different sort of screened bottom. Sounds like a lot more work than using actual screen.

Yes, it would, although it would be more mouse-proof than most plastic meshes, relatively easy to clean and mites would probably drop through more readily. I think its main benefit would be better draft control - less air penetration per unit area, but still providing good ventilation.

I thinking that an attic would address a lot of these problems. Insulation below the vented attic would keep the temperature down in the summer and if the insulation is absorbent could move moisture out of the hive during the winter without introducing drafts. I think newspaper would work perfectly. I can say authoritatively (having slept on the ground under some newspaper) that its a surprisingly great insulator and its free.

Newspaper is good, but make sure mice can't get at it. I took the roof off a hive recently that had a chewed-newspaper mouse nest arranged neatly right over the bees' winter cluster - bee-powered central heating!

An attic is definitely the way to go, and I suggest you enclose your absorbent insulation in a wooden box, as the Warré people do.

And don't neglect floor ventilation.

Zonker

Discussion Starter · #7 · Mar 18, 2010

What do you think about square sides? I'm thinking it would be convenient to be able to hang a lang frame in the hive so that I could buy local nukes instead of imported packages.

buckbee

· #8 · Mar 18, 2010

Zonker said:
What do you think about square sides? I'm thinking it would be convenient to be able to hang a lang frame in the hive so that I could buy local nukes instead of imported packages.

Personally, I don't like them. They create a much larger volume per unit length for bees to deal with, and square/rectangular combs are much more difficult to handle and prone to break-offs.

You could make a hybrid, with vertical sides to accommodate a nuc and sloped sides for the rest.

Duboisi

· #9 · Mar 20, 2010

Hi

I am planning on starting with bees this summer, and have been thinking quite a bit about hive design. Especially as the planks that I bought earlier this winter are 20 cm wide(40 cm when two are joined together) and 2cm thick. While most plans I see recommend 30 cm with and 2.5cm thickness.

Still - it seems like while 2cm thickness is not ideal, it should work.

Anyways. After reading about bottomless hives, I just got the idea of making a V shaped hive with a 2-3 cm opening at the bottom. About 30 cm from the top, I will install a mesh that will serve as a comb-building floor and let varroa trough.

This will give a 10cm empty space underneath, and together with the small opening, it should give protection from the wind while allowing moisture to escape.

I have made a simple sketch of my idea:

Does this seem like a good idea?

BTW: I live in a wet climate with fairly mild winters - although this year was a record one with temperatures down to -15 or so for several days on row. Right now there are still snow on the ground(!). Normally there will be a week or three with a little snow, and a week here and there with temps below freezing.

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WLC

· #10 · Mar 20, 2010

Maybe if the wind blows at just the right speed, your hive might resonate like a musical instrument!

Shazam

· #11 · Mar 20, 2010

I dunno, but with that much spare room under the mesh that is still shielded from elements, you may find some bees starting to hang comb from the mesh too. That would be my only caveat, and that's only from reading some quirky hive tales. Dunno.

Duboisi said:
Hi

I am planning on starting with bees this summer, and have been thinking quite a bit about hive design. Especially as the planks that I bought earlier this winter are 20 cm wide(40 cm when two are joined together) and 2cm thick. While most plans I see recommend 30 cm with and 2.5cm thickness.

Still - it seems like while 2cm thickness is not ideal, it should work.

Anyways. After reading about bottomless hives, I just got the idea of making a V shaped hive with a 2-3 cm opening at the bottom. About 30 cm from the top, I will install a mesh that will serve as a comb-building floor and let varroa trough.

This will give a 10cm empty space underneath, and together with the small opening, it should give protection from the wind while allowing moisture to escape.

I have made a simple sketch of my idea:

Does this seem like a good idea?

BTW: I live in a wet climate with fairly mild winters - although this year was a record one with temperatures down to -15 or so for several days on row. Right now there are still snow on the ground(!). Normally there will be a week or three with a little snow, and a week here and there with temps below freezing.

Duboisi

· #12 · Mar 20, 2010

@VLC: You might be correct. Something to consider when placing it. But then again - it has to be tested to be confirmed/debunked.

@Shazam: I have been thinking about the same. But hope that as long as the netting is not big enough for them to get down from the inside, they will not make combs in the void. Guess it would be a bit of a problem with inaccessible combs - both for the bees and the beek. If it becomes a problem - it could be resolved by putting netting at the bottom aswell.

Or one could make it a bit shorter(to avoid overly large comb), and let them build to the bottom without any screens and use the bottom as entrance. According to some http://www.beesource.com/point-of-view/charles-martin-simon/bottomless-beekeeping/ this might be a viable option.

Zonker

Discussion Starter · #13 · Mar 22, 2010

Might be hard for a new hive to defend itself with all the open door space.

duncan_bees

· #14 · Mar 22, 2010

Zonker said:
Might be hard for a new hive to defend itself with all the open door space.

I know Phil Chandler is promoting unscreened hives. I wonder what he has experienced with installing bees in a bottomless setup.

buckbee

· #15 · Mar 22, 2010

duncan_bees said:
I know Phil Chandler is promoting unscreened hives. I wonder what he has experienced with installing bees in a bottomless setup.

I wouldn't say that I promote them - just that mine seems to work despite everyone's predictions. It has come through 3 winters - two of them unusually cold - and seems to be strong and healthy.

HOWEVER - this very morning I checked it and found that a badger had - for the first time - gotten its head underneath and ripped out soime comb. I think the bees must have given it a hard time as best they could, but badgers are tough customers and capable of doing a lot of damage if they choose to. The hive was perfectly intact and the bees still there, but not quite as pleased to see me as usual. I drove some stakes into the ground close to the hive to slow the badger down should it return, but I will have to do something more drastic as a permanent cure. If it is to remain essentially bottomless, I will either have to fix a course mesh - like chicken wire - over the bottom, or some bars.

duncan_bees

· #16 · Mar 22, 2010

I doubt those of us across the pond would have many badger incursions, but this could definitely be an issue with skunks and possibly opossums. Armadillos in Texas?

WLC

· #17 · Mar 22, 2010

I'd worry about rats.

buckbee

· #18 · Mar 23, 2010

WLC said:
I'd worry about rats.

Yeah, but you live in New York!

Wyldbee

· #19 · Mar 23, 2010

Zonker,

You may want to "search" TBH Ventilation thread. Someone mentioned using Dow Foam. There is a link to Warre' quilts that could be adapted to our hives too.
Check out http://beenatural.wordpress.com/natu.../condensation/ has an interesting article does not seem to apply to TBH but good food for thought.

I am still waiting for my bees so I do not have any first hand experience , However I have been reading a TON!

Good Luck!

Duboisi

· #20 · Mar 24, 2010

I am thinking that one need enough ventilation, and a roof that is more insulated than the walls. Making me very positive to the concept of using Warre-style roofing.

Open-bottom may be too much ventilation, but still I would like to give it a try. Anyways there have to be a way for the humidity to get away in a humid climate.

The roof should be more insulated than the walls, so that any condensation happens away from the cluster. If there are snow at the roof, it will offcourse work as a really good insulator.

Guess it's down to what Zonker wrote in the first post - It's all about the local climate.

Mine is mild winters with little snow and frost, and relatively cool summers. There are normally plenty of rain throughout the year.

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