Attic ventilation
If there is one line in a Minnesota roofing quote worth arguing about, it is this one. Attic ventilation decides whether ice builds at the eaves in February, whether the shingles bake from below in July, and whether the covering that just went on will reach the age printed on its wrapper.
What balanced actually means
Ventilation is a pair, not a product: intake low at the soffits and exhaust high at the ridge, sized to each other so air moves continuously through the attic. The goal in winter is counter-intuitive — you want the attic COLD, at outdoor temperature, so the snowpack above it never melts from below. In summer the same airflow carries out the heat that would otherwise cook the shingles from underneath. One system, two jobs, both of which the covering depends on.
The most common failure is not missing vents but unbalanced ones: ridge exhaust installed with no matching intake, or soffit intake buried under insulation that was blown in over it. Exhaust without intake pulls conditioned air up from the house instead of drawing outdoor air through the attic, which makes the ice problem worse rather than better. On the metro’s 1990s and 2000s production housing, builder-minimum ventilation met code and stopped there — and twenty-five winters later the debt is visible on those same streets every February.
Replacement day is the cheap moment
Correcting ventilation as a retrofit means working around a finished roof. Correcting it while the deck is open costs a fraction — new intake, properly sized ridge exhaust, baffles that keep the soffit path clear of insulation, bath fans ducted outside rather than into the attic. None of it is glamorous and all of it is cheaper than the alternative, which is a new covering aging on the same schedule as the one it replaced. Make it an explicit line in the quote: “we reinstall the existing vents” is not a ventilation scope.