Conflict with roofer
One of the first things you might want to do is look into the building codes in your area to make sure that the work performed meets code. In Montgomery County, Ohio planked sheathing is considered spaced sheathing. Therefore as roofing contractors, due to code, we have to install 3/8 or 7/16 OSB over-top of the existing planks to meet building code. Many contractors in my area do not know this code, or if they do they just ignore and continue to violate. Hope this helps and best of luck with your situation.

http://www.mcohio.org/services/building/docs/Roofing_Issues_Policy_13RCO.pdf


Can I use the existing roof sheathing?
Section 905.2.1 states “Asphalt shingles shall be fastened to solidly sheathed decks.”
Therefore, if the existing sheathing is in structurally sound, it can be used for the new
installation.
Exception: If the existing roof sheathing is spaced lumber or damaged such that it
will not hold a nail, it must be covered or replaced.