Venting A Roof Valley

Ice dams form when a home s escaping heat warms the roof sheathing and melts the underside of the snow layer on the roof.

Venting a roof valley. 2 if you re going to vent the roof then vent the roof. The valley area of a roof the straight lines formed when two different planes of the roof meet is a critical area that handles a tremendous amount of water run off. In cold climates snow can enter the soffit and ridge vents melt and potentially cause rot. Applying the smooth side down nail in place install one vent per rafter in all valley areas and apply roof sheathing plywood over the valleyvents and nail.

That means the entire perimeter of the roof needs to have air inlets meaning continuous soffit ventilation. Beyond the decreased capacity for insulation when venting the roof deck venting the roof deck or the attic has some other drawbacks worth considering. Valleys are typically found where gable dormer roofs meet the main roof or when a house has angled wings or additions where two roof sections in different planes meet. The intent of roof venting varies depending on climate but it is the same if you re venting the entire attic or if you re venting only the roof deck.