A method for facilitating ventilation and/or drainage in a building wall, floor, and/or roof by the step of: placing a foam insulation board with an interior board face and an exterior board face, at least one board face having ventilation and/or drainage grooves and/or protrusions into the building wall, floor, and/or roof; providing vents in the building wall, floor, and/or roof adjacent end portions of the insulation board, whereby ventilation is facilitated within the wall, floor, and/or roof of the building by air moving through the vents, along the grooves and/or protrusions of the foam insulation board, and out of the vents, drainage of water is facilitated within the wall or the roof of the building by a pathway created by the grooves and/or protrusions, and moisture removal is facilitated by the passage of air during ventilation.