Moisture under roof of flow hive

i have one flow hive that requires painting, but the paint on roof starts lifting within a yr. the wood under the roof is very ‘wet’. should i have better ventilation? there is similar moisture on top board adn roof of the cedar hives.

Did you use an exterior grade of paint Dennis? If you did then maybe you didn’t use a primer of apply enough coats of paint, it shouldn’t be failing after a year. My climate is a very wet Summer and found condensation inside the hive a big problem both in my Flow Hives and the traditional Langstroth’s with migratory roofs. I added a 35mm kitchen cupboard vent to each end of all the roofs and it dramatically reduces the moisture in the hive that was dripping from the inside of the roofs. I bought the vents for $5 a pair from my local hardware store. The vents have a mesh so are bee proof.

painting was done correctly as i did not do it… not my gig so hand balled to better half
i had made small vents so from what u have said they need be bigger

ta again

I use the 35mm vents that were in common use in kitchen cupboards till about 40 years ago. They work for me.

Hi Peter,
Thanks for that. Can you please elaborate on the vents with the flow hives in conjunction with the crown board? Do you leave the hole in the crown board open or closed? Do you put vents in the flow hive or more langstroth? If you leave the crown board hole open, do you then use a hive mat or a mesh to cover the hole? I find it confusing as people talk about using vents, but it’s often hard to tell whether they’re referring to conventional langstroth or flow hives.
I’ve made a couple of pitched roofs for new hives (for intended use with flow supers) and put the circular mesh vents in that you mentioned. I’m not sure how they work with crown boards or no crown boards, with or without holes open / closed. To date, I’ve left the hole in the crown board closed, unless used for feeding. I hope this isn’t too confusing.

Mesh or plug the hole and add a couple of vents to the gabled roof.

If the bees don’t want the ventilation they will block the mesh over the crown board hole, but don’t use fibreglass mesh as bees will chew through it.

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In you grandmothers kitchen all the cupboards has a vent fitted to each of them. $5 a pair and still available from a hardware store, the vent has a bee proof mesh. They are fitted in all my Flow Hive roofs and the Langstroth migratory roofs, one at each end. A hive mat can stop condensation dripping in the frames but the vents help in venting the high humidity out of the hive. I fit fly screen mesh over the hole in the crown board held in place with duct tape. The mesh can be removed for internal feeding if needed. I have always had the plug removed from the crown board.
Some have used shredded paper or wood shavings above the crown board under the roof to absorb moisture.
Hope that explains it better.

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Thanks Stevo. That makes sense. I didn’t even know there was such a thing as fibre glass mesh. I’ll try and steer clear.

Hi Peter - yes I bought 35mm circular mesh vent disc type things from Bunnings. I hate to be the bearer of bad news, but I got not 2, but 4 for $5 (assuming we’re taking about the same thing).

Thanks for the detailed info - that is much clearer now and i appreciate it very much!

Fibreglass mesh is the stuff in most fly screens, you need the aluminium one but my bees seem to be stripping the paint off that and I’m not sure how long the aluminium will last lol.

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Ok, so what is condensation caused by?
Dew point; the atmospheric temperature (varying according to pressure and humidity) below which water droplets begin to condense and dew can form.
Insulate your ceiling so there is a lower temperature difference between the inside and outside and there will be less dew, or condensate, forming on your hives ceiling.
We talk about how clever bees are, that they can even cool their homes in summer using evaporative control keeping it 34⁰C±2K. Amazing eh?
So why do people want to climate control their bee hive? Don’t we think they know what they’re doing?
We don’t need to put fans in the hives summertime, well most don’t anyway, why remove warm air wintertime? Yeah it’s humid air but perhaps that’s what they want…
I can not get my head around the baseless advice given to add vents into the tops of hives over insulation with no sound proof that it is in any way advantageous for the bees.

The bees are still conditioning their hives atmospheric conditions wintertime.


I bought mine from my local hardware store 300 meters away, my nearest Bunning’s is a 30 km round trip so not practical for just the vents and sure if I went there I would have bought something I don’t really need. :smile:

The only reason we have vents is because of the dominance of commercial beekeeping principals centred around migratory beekeeping.

Prior to that almost all hives had telescoping tops, the vents were only added to stop the hive cooking in transport.

I used insulated lids on both my hives over winter, one was mostly dry but the other one was wet enough to get quite mouldy so I gave them a lid with vents and it cleared up, they’re still wet though. They will block them if they don’t want them.

You might consider that the bee keeper can make the hive more comfortable for the bees in controlling the internal temperature and humidity of the hive, this then frees up more bees for other chores. What harm is done by reducing hive temperature and humidity if the bees benefit from doing it?
Your of course entitled to care for your bees as you wish and if you accept that then others are also entitled do do the same. My advice is based on 48 years of bee keeping in extremely hot and humid climate. The sound proof you claim doesn’t exist is that adding vents cured the issue of bearding the same day I fitted the vents.
I accept you can’t get your head around that and maybe your climate isn’t as hot as others that have fitted vents and seen the benefits.

I never had issues like comb collapse and melting in transporting my hives but in heat waves at Bathurst and Mudgee it was a real issue, back then the normal was to put a twig under the edge of the roof to allow the heat to escape. Maybe when transporting the hives the wind over the hives helped in cooling them.
It was decades later that I saw hives on a truck with vents in the migratory roofs and started trying them. Many said the bees would block the vents every Winter but it didn’t happen with my hives, but maybe in a really cold climate the bees might block them to save heat loss.
Only about 10 years ago did my local bee gear shop stock roof with vents, he says they out sell un-vented roofs by a mile.
What is the reason that your two hives are so different do you think? Anything noticeable?
Cheers Steve

Masonry paint :+1: works a treat.

Cannot agree more. It is elementary physics.

Yes, top venting will eliminate some of the condensation, and not much humidty BTW. It comes at an enormous cost - heat loss.

The cupboard-vent-brigade can see condensation, but unfortunately, heat loss is not visible with the naked eye. You need a thermal camera.


It is not hard to imagine what happens to the heat inside these hives if vented at the top. The more heat they loose the more they have to regenerate, needing energy… by eating more honey. Probably more bees die too, but no one is counting.


Probably genetics and strain of bee. I was told the queen of the wet hive was from a breeder in the NT, which is one of the wettest parts of Australia.

The migratory lids we originally used here are very different to the ones we have now, look up US style MG lids for pics. They’re just a flat sheet with two spacers on one side used in combination with a mesh screen.

During transport they’re put on with the spacers facing down, so the mesh is almost fully open, then flipped over when placed on site effectively dealing the hive at the top.

I can only guess as to why we changed but I would think it was just because it was less work using ones that didn’t have to be flipped over.

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Turns out that after 2 weeks they didn’t like the vents so I’m back to using insulated lids on both.

Weird thing is how they’ve blocked the vents, usually they do the individual holes not the whole thing.


It will be interesting if they close off the air flow completely Steve or if they open them up again in the hot weather… None of my roofs have the vents closed off by the bees, but it is a lot warmer Winter up here.
Keep me updated Steve please.