With regard to the placement of underlayment, Air Vent recommends it be placed both under The Edge Vent (i.e. directly on the deck) and over The Edge Vent. NOTE: The slot should also be cut into the underlayment that is applied directly over the roof deck slot before securing The Edge Vent to the roof.

Use the type of underlayment commonly used for the specific climate and ensure that local building code requirements are met. For example, in snow regions, the underlayment typically used at the edge of the roof (e.g. ice and water shield) should be installed over the top of The Edge Vent to ensure proper protection from any water that could potentially backup under the shingles on the roof top. Additionally, Air Vent recommends that the same underlayment also be used to protect the roof deck directly beneath the vent in northern climates. In warmer regions of the country, with little or no snow, the use of standard shingle underlayment beneath and over The Edge Vent should be sufficient.