Take the 2-minute tour ×  What happens if the attic vents or
rafter baffles don't cover the entire opening between the
rafters and one or two inches of wood is left exposed?
share|improve this question add comment  1 Answer  A vented
soffit allows air to flow in. The ridge vent allow the air to
flow out. The purpose of this attic venting system is to keep
the roof deck at approximately the same temperature as the
outside air across its surface so that melting snow won't form
ice dams. The venting system is not there to cool the attic
volume itself.  If the baffles are not properly installed so
that they guide the incoming air up to the underside of the roof
deck, air may be blowing through the insulation, a process
called "wind-washing". This will displace loose fill insulation
like cellulose and will reduce the R value of batt insulation
which relies on still air for its effectiveness.  share|improve
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