Spray Foam Underside Of Roof Deck

Unvented roof strategies with open cell and closed cell spray polyurethane foam insulation sprayed to the underside of roof sheathing have been used since the mid 1990 s to provide durable and efficient building enclosures.

Spray foam underside of roof deck.

Unvented roofs with spray foam applied to the underside of the roof deck have been used since the mid 1990s. There have been isolated moisture related incidents that raise potential concerns about the overall hygrothermal performance of these systems. While covering a given area with spray foam costs more initially than the equivalent amount of mineral wool batting or other insulating materials its ability to fill even tiny spaces completely enables it to provide greater thermal resistance leading to greater energy efficiency and. The movement of air into indirect conditioning of an unvented attic is a slow gradual process that will not be noticeable by occupants and typically will not put any strain on the hvac system.

Moisture generated indoors or that infiltrates into the home is responsible for the bulk of the moisture in an attic insulated with spray foam on the underside of the roof sheathing. Spray foam insulation applied on the underside of the roof deck in cold climate commercial buildings allows for a significant reduction in condensation potential particularly compared to interior air permeable batt systems. Spray foam can prove something of double edged sword where costs are concerned according to rlc engineering. It s not coming from above the roof and it s not some new moisture source resulting from the spray foam.

But spray foam insulation used at the underside of the roof deck would need to be covered by a thermal barrier and intumescent coatings are commonly used.