Knee-wall attics
The Cape Cod and the split-level are the two houses this region built by the thousand, and both do something to the attic that changes roofing: they put finished rooms inside it. What is left is not an attic but a set of awkward triangular pockets behind short walls — and those pockets are where the roof above quietly loses years.
Why it is not an ordinary attic
A conventional attic is one open volume: air comes in low at the soffits, rises, and leaves at the ridge. A finished Cape has no such volume. There are short walls — knee walls — with a small dead space behind each one, then insulated rafter bays running up over the finished ceiling, then perhaps a small flat attic at the top. Air cannot simply flow through that, and in most houses of this vintage nobody tried to make it.
The consequence shows in two places. In summer the rafter bays hold heat against the underside of the deck, and the covering ages from both sides at once. In winter, warm air escaping into those bays melts snow on the roof above while the eaves — which overhang unheated space — stay cold, so the meltwater refreezes at the edge. That is where ice builds, and it is a ventilation problem long before it is a roofing one.
What a real answer looks like
Continuous baffles in every rafter bay from the soffit to the ridge, an intake that is actually open at the eave rather than buried under insulation, and an exhaust sized to match. On a finished Cape that is genuine work, and it is done properly only while the roof is off — which makes replacement day the one sensible opportunity. Be direct with bidders about it: a quote that says the existing vents will be reinstalled has not addressed a knee-wall house at all.