wrote:

I'd say it's very likely you don't have enough soffit venting. A 2 1/4
inch one every 4 feet isn't very much.

IIRC, it was 3 holes every 4', ie 0.083 ft^2, or half that as open area and
twice for both soffits. If each 600 ft^2 of attic needs a 1 ft^2 vent, with
a vapor barrier in the ceiling and equal high and low areas, those 3 soffit
holes can vent 49.7 ft^2 of roof, ie a 4'x12' section. We might want 6 holes
per 4' of 24'-wide roof, or a 2"x14.5" screened soffit slot.

As an alternative, a WXL' attic might have WL/600 ft^2 of screened vents
at the top and bottom of each endwall. A 30'x40' attic might have 4 1'x2'
gable vents placed high and low, which might be covered in wintertime to
conserve heat. IMO, continuous ridge or soffit vents are not required to
eliminate "hot spots," since air can flow freely inside an attic.

Nick