Gable end wall in attic. Wood siding installed over lapped felt placed upon studs. From the attic view point you can see the felt. It was common in older homes.
Is exposed felt in an attic against code or an item to write up? Argument is flame spread rating.
assuming that the felt paper was manufactured as a roofing underlayment it would have to comply withe the ASTM standards for flame spread and it is much lower than the exposed framing lumber
Yes I have seen this in Montreal. Common I would disagree.
Now it looks like a knee wall was cut away in my opinion. It was replaced by a jack stud. Any more photos or the attic?