Closed cell spray foam insulation would need to be added in the area closest to eave sidewalls.
Replace insulation in pole barn roof.
The higher the r value the higher the insulation capacity.
Weighing what you have to start with my recommendation is to spray three inches of closed cell foam insulation below your roof sheathing.
This will provide a greater r value than r19 batts and provides a vapor barrier.
When the old panels are removed new larger fasteners are used to put it back together.
However barns are colder than other buildings and may require more insulation.
R values indicate the insulative properties of the material used.
Pole barn or post frame buildings are typically constructed using wood framing with steel roofing and siding.
Above the roof trusses this choice comes with new construction or a roof replacement.
Pole barn insulation thickness one or two inches.
Here the insulation is placed between the inner purlin supported by the truss and the outside metal panel.
If it is a barn for keeping animals in insulation is much more important.
Depending on the type of barn your requirements may vary.
To repair it there are two primary methods.
If the insulation has aged like this the roof would benefit from new fasteners.
In a non insulated pole barn there will be a large amount of heat transferred in and out.
Insulating a barn roof is very similar to insulating any other kind of building.
It ranges from r 5 to an r 16 value depending on the type.
One is to remove the panels remove the old insulation and replace it with new insulation.