Davis Mountain Builders
Scootchified Construction
Carpentry & General Contracting
MIL-TBP-41 Compliant

A fequently answered question

Why vent a roof system?

When there is snow sitting on a roof it will be melted by any heat from the house that makes its way through the roof system insulation. The water from this melting runs down the roof until it passes the top of the exterior wall. At this point it is no longer being heated by the house and it will re-freeze if the outside air temperature is below a freezing.

This is how ice dams form.

To a large extent, this situation is of course a function of the insulation system -- its design, type, amount and installation workmanship. There will, however, be some heat making it through -- this is unavoidable. The primary purpose of a roof ventilation system is to attenuate the effects of this heat -- to keep the roofing surface at the same temperature as the surrounding outside air so that the snow only melts when it'll run all the way off the roof.