I have seen two thoughts.
Roof sheathing ridge gap.
This is a simple pitched roof line with ridge beam and rafters attached with slope hangers.
How should the sheathing meet at the roof peak when there will be no ridge vent.
Vents evenly spaced underneath the roof provide intake.
So you re talking about you re going to reroof and you have a gap between the wall sheathing and the roof sheathing.
Ridge vents when the roof sheathing is used as a structural diaphragm as it typically is in high wind and seismic hazard areas the structural integrity of the diaphragm can be compromised by a continuous vent see figure a below left.
The house does not have an overhang.
This gives you 450 square inches of total exhaust.
Leave a 3 mm 1 8 inch gap between the osb panels to allow for expansion.
But where the wall sheathing meets the roof sheathing there is a gap of approximately 1 8 of an inch.
Ridge vent installation in new construction the roofing contractor leaves a small gap at the peak of the roof when installing the roof sheathing.
It s a simple gable roof with vents at either end and a ridge vent.
The gap size typically between 1 and 3 inches.
Multiply it by 18 square inches the net free air per foot of ridge.
And i was advised that that gap should be protected by a home inspector.
The last course at the top may need to be rip cut if the roof is not in 4 foot increments.
It is important here that the sheathing at the eave line be exactly perpendicular to the rafters so that the sheets will meet at the centers of the rafters.
Roof trusses must be dry when sheathing a roof with osb to prevent mold growth in the roof and coverage gaps as the trusses dry and shrink.
Now wait a minute.
Begin applying the sheets from the bottom of the roof the eaves and work your way up to the ridge.
Stagger the panels over the roof with 2 supports between panel ends.
Avoid butting osb panels tightly.