Hay storage

[Mardi1]

Recently the barn owner where I board installed a professionally made wooden shed (Tuff Shed) to store the baled hay. The shed is approx. 12’ x 14’ and 15-20’ in height with a peaked roof. There are 2-3 slotted type small vents near the roof.
One of the barn workers commented to me that when the weather is very warm, the interior of the shed becomes hot, since there’s no airflow in the shed, and the doors are kept closed.

I always thought stacked baled hay needed adequate ventilation. If there’s no airflow, will it affect the quality of the hay ? Thanks for any input.

[FitToBeTied]

It sounds like you are talking about ridge vents. If so it should be fine.

[SusanO]

That will depend on your climate. If you are in a climate with low humidity you should be fine. If higher humidity you could have condensation and dew dripping on the hay or just humid air stuck in there and over a long period the hay will be getting musty on the outsides of the bales. Hot dry air is fine.

[Simkie]

Properly cured hay will be fine.

Wet hay (either not dried enough in the field, or wet from a leaky roof or something) is a risk, even outside of warm temps.

[clanter]

would have been nicer if there had been a second set of doors on the opposite end of the building if for no other reason to access the hay in the back to make rotation of the stored hay easier

With doors on the both ends ventilation would have been easier

A carport structure might have worked much better and possibly much less expensive than an actual enclosed building.

[Mardi1]

Agree about doors on both sides, however the back of the shed abuts a cinder block wall, so the front doors are the way in and out.

Thanks everyone for your input. Really helpful.

[poltroon]

The quality of the hay would worry me less than fire.

The thing to really watch for is any condensation. Any at all can not only mold the outside of the hay but create a drip line of moisture into the hay that can travel remarkably far down. And this not only causes mold but more alarmingly, it can generate spontaneous combustion in the hay. It is astonishing how hot a bale that is wet on the inside can get, and how hard this is to see if it is happening deep in the stack.

In general, I would not recommend keeping doors closed on a hay storage building. If they need to keep people (or horses) out, a mesh gate might be a better choice.

[Mardi1]

@poltroon

The thing to really watch for is any condensation. Any at all can not only mold the outside of the hay but create a drip line of moisture into the hay that can travel remarkably far down

Please walk me through how that works. Does the hay itself create the condensation on the ceiling ?
Is the creation and/or amount of the condensation related to the humidity level outside ?

[SusanO]

If you have high humidity inside the container - say 75% and the dew point is 70 degrees. The temperature drops to 60 degrees so you get condensation inside the container and if the roof is metal you can get water dripping on the hay bale. Most of these structures are not that air proof so if you have high humidity outside you will have high humidity inside. If the hay is touching the ceiling or floor or sides that condensation will be wicked into the hay. The hay does not bring the humidity (if it is baled at a low moisture point which it should be) . It is like walking out on grass at night and the grass is wet even though there has been no rain for weeks. Or hay bales you left out on the truck at night when it does not rain and you don’t want to unload them yet. The bales exposed to the night air will be damp on top in the early morning. Dry, low humidity climates don’t have much problem with this.

[poltroon]

What SusanO wrote, but the hay doesn’t necessarily have to be touching the ceiling. What can happen is that water condenses on the roof and due to the geometry, it might migrate to a particular line or point and drip, drip, drip into a single point or line on the hay. (Leaky roof same issue.) Then, this moisture can travel down into the center.

A bit of moisture evenly distributed on the outside is not nearly as big an issue.

If the roof is wood or insulated it is much less likely to have this issue than if it is metal.

[clanter]

depending upon soil a source of condensation could easily be from the ground the building is setting upon if there was not a vapor barrier under the building

[cardinale]

A hay dealer told me here (in the wet PNW) to cover hay stacks with moving blankets, to minimize/prevent bad condensation. Of course, the hay still needs to be under a roof, but the blankets help with atmospheric-type moisture.