Put animals in an arch building and you create a problem the shape was never designed for. Quonset spray foam insulation in Rocky Mountain House often comes up on a building being used for stock or calving, and the honest starting point is that a quonset is harder to ventilate than a conventional barn, because it does not have the thing a barn ventilates through.
No ridge, no easy exhaust
A gable barn has a ridge line, and warm damp air rises to it and leaves. An arch has a continuous curve with no natural high point running its length, so the moist air rises, spreads along the underside of the shell, and finds the coldest steel instead of an opening. That is why a quonset holding animals soaks itself faster than a comparable barn does, and why sealing it without a plan for getting the air out makes it worse rather than better.
Seal first, then extract on purpose
The order does not change and it matters more here. Air seal the shell so you control where air moves, then move the air out deliberately at a rate you have chosen, which in an arch generally means mechanical extraction and planned inlets rather than relying on the building to breathe. Foam does the first half properly. It does not do the second and must never be sold as though it does.
Why the water is a bigger problem than the cold
Animals put moisture into the air continuously, bedding holds it, and in an arch that moisture has nowhere to go but the steel. A damp building is worse for stock than a cool dry one, and it works the structure hard, because water sitting on the inside of a shell is how these buildings corrode. Removing the cold surface stops the condensation forming; the ventilation removes the water that caused it.
Foothills weather makes the swings sharper
Up against the foothills the temperature moves quickly and the daily swing under a clear sky is wide. A bare arch radiates heat to the sky overnight and drops below the dew point of the air inside it very easily, which is why these buildings can be dripping on a night that is not especially cold.
The shape decides the product
A quonset has no stud bays and no flat planes, so batt has nothing to sit in and rigid board cannot follow the curve without leaving voids. A void against cold steel is where water collects and it is hidden. Foam bonds to the shell and takes its shape. It needs clean dry steel, and where the building holds animals the covering requirement over the foam is part of the specification rather than an afterthought.
Quonset Spray Foam Insulation Rocky Mountain House: Common Questions
Is a quonset a good building for livestock? It can work, but it is harder to ventilate than a gable barn because there is no ridge for the moist air to leave through, and around Rocky Mountain House that is the common use for these buildings. That has to be designed rather than assumed.
Will insulating stop the barn being damp? It stops the condensation forming on the shell. The moisture the animals produce still has to be extracted deliberately.
Why does it drip on nights that are not that cold? The steel radiates heat to a clear sky and falls below the dew point of the air inside, which does not take much of a temperature difference.
Estimate the thickness with the R-value calculator, then get a free Rocky Mountain House quote. More on Quonset Spray Foam Insulation Alberta province-wide.