Wet Roof

[thundercat]

When the weather was nice, I lifted the roof on my hive to check on the bees. One of the things that I was shocked to find was that the wood inside the roof was wet, and showing signs of mold growth. I replaced the roof, but I am stumped by the cause.

I took the roof apart, and found that the top of the wooden roof (under the metal hood) was wet, and the bottom was damp. I checked the metal hood for any leaks, but there was none.

Has anyone had any similar experience with a wet roof? The hive consists of two brood boxes, and one theory that I've been given is that it's the bees, but as I said the water was on top of the roof (underneath the metal).

Thanks in advance

 

[Skyhook]

Sounds like condensation from the bees moisture. Is the crown board insulated? Has the roof got vents? I've got something similar, I need to increase the roof ventilation. I have foil backed insulation on the crownboard, so not much moisture gets through, but a bit will, then of course thecold roof is a perfect condenser.

 

[Finman]

.
That has been usual to me and the reason are these:

- the inner cover is so cold that moisture condensates into the cover.
Moisture condensates onto cold surfaces. - more insulation that moisture condensates on side walls.

- if you have wood, insulation board and metall rain cover over them, moisture move throught the wood and insulation and meets dew point. It is place where water turns tp liguid.

- I have metall roof plus insulated inner cover. Between them must be a ventilation gap. If insulation stuff touches to the rain cover, onto rain cover condensated water drills back to the insulation

I just took off too thick insulations. They touched the outter cover and condensated water had made them very wet and icy.

 

[thundercat]

Water

The roof board had two vents, and there is obvious evidence of water leaking through those vents (see pics). The top of the roof board (just below the metal cover) was soaking, while the bottom was damp (with mold starting to grow [see pics])

There is no insulation in the roof space (just the crown board with a mesh blocking the vents), as I thought that would increase condensation. The bottom of the hive has a mesh screen, so ventilation is good.

Should I insulate?

 

[Skyhook]

Definitely add insulation. The OMF gives all the ventilation you need, so no problem with blocking feed hole completely. 2" (50mm) of polystyrene, kingspan or similar. Instead of continuing on up to the cold roof where it condenses above the bees, the warm moist air rising from the bees will (by convection) then return back down the sides of the hive, condensing either on the sides or at the OMF, where it it can drip harmlessly to the ground below. This assumes that the hive is raised on some sort of stand so that the condensation is not trapped beneath the floor. If it isn't, it should be.

The roof vents should ensure that the roof space, completely separate from the main hive, stays dry. At the moment they are being overwhelmed by the amount of warm moist air coming through the feed hole.

 

[rowbow]

The crown board should have all feed holes closed, put insulation on top, the OMF floor will let fresh air in and the moist air will go too the brood box wall's and will run down and out the OMF, if the roof is still wet, it's leaking.

John

 

[Storm™]

Between the metal of the roof and the wood of the roof. So when you took it apart it had water up inside the layers. As well as what everyone else says, I would suspect high winds blowing any rain up between the layers. That and a thing called capillary action. Where water will actually travel uphill if the gap between the two is just right. I have seen this from bathrooms to my landrover. To prevent it run some sealant around the inside of the wood before you replace the metal. This should seal that cavity. Unless I read your explanation wrong in which case i'll shut up. Good Luck.

 

[Skyhook]

Between the metal of the roof and the wood of the roof. So when you took it apart it had water up inside the layers. As well as what everyone else says, I would suspect high winds blowing any rain up between the layers. That and a thing called capillary action. Where water will actually travel uphill if the gap between the two is just right. I have seen this from bathrooms to my landrover. To prevent it run some sealant around the inside of the wood before you replace the metal. This should seal that cavity. Unless I read your explanation wrong in which case i'll shut up. Good Luck.

Quite possible. However, as OSB isn't vapour-proof, and a metal cover makes a great condenser on a cold night, I still think that's the most likely cause; or at least likely to be one of multiple causes.

 

[Storm™]

LOL@Skyhook yup it will more than likely be more than one cause. Like I have seen on many forums:

"Start off fixing the cheap stuff to fix, then look at the expensive time consuming options"

 

[thundercat]

Fingers Crossed

On the next fine day, I'll replace the crown board (so that the vents are sealed), and add some insulation in the roof space. I have some insulation used for lining the roof space (in a human house, and it's made from recycled plastic bottles), so I'll put that in and see how we get on.

 

[Finman]

On the next fine day, I'll replace the crown board (so that the vents are sealed), and add some insulation in the roof space. I have some insulation used for lining the roof space (in a human house, and it's made from recycled plastic bottles), so I'll put that in and see how we get on.

newspapes are good insulation material too.

 

[oliver90owner]

On the next fine day, I'll replace the crown board

No. Simply close off the hole(s) in the crownboard, insulate over it and replace the roof if you have spare. Otherwise cover temporarily and dry it out.

No need to remove the crownboard whatsoever. So do it now!

RAB

 

[Finman]

.
It is not a big job to correct situation. One of the smallest in beekeeping.