Looks like building felt back there.
That is not supposed to be left exposed, nor is it considered a weatherproof siding.
Remember (if you've seen them) those "tar paper shacks" ... little shacks people lived in which has "tar paper" wrapped around them to try to keep the weather out?
That there is just a modern version of those "tar paper shacks".
Was there even anything behind that building felt, or was it just wrapped over the studs?
Water, cold, heat, insects, rodents, birds, you name it - that stuff is not going to stop anything.
It will, however, make for a nice "moisture sandwich" keeping moisture between those few-and-far-between siding boards and that building felt.
Was that architect a graduate of Acme? (Of Roadrunner and Wiley Coyote fame.
)
