A ridge vent assembly extends along a roof ridge of a building. One embodiment has corrugated plies defining small diameter passages that communicate a vent opening cut along the ridge of the roof with ambient atmosphere. A moveable valve member extends along the outer edge of the vent parts and includes a lift spacer to keep the valve member spaced from the roof when in an inactive position. When wind speed increases above a predetermined wind speed, the movable member moves into a position adjoining the edge of the vent parts and the bubble is compressed against the upper edge of the corresponding vent part, thereby preventing entry of wind driven moisture and snow into the passages and into the building structure through the vent opening. Accordingly, the moveable valve member acts as a weatherstripping material for the vent. A similar flexible member is usable to weatherstrip windows, doors, and other building openings.