Insulating The Roof Deck

The moisture is held in place by the insulation which allows for damage to the framing and other building components.

Insulating the roof deck. Insulating the pitched roof. Generally more insulation is needed for condensation control in colder climates. Rigid foam insulation boards. If your attic is often used or perhaps you plan to convert it in the future you will need to insulate the inner surfaces of the roof.

Air sealing hot roofs is critical. You may also insulate your roof to help regulate the temperature in an attic that is a part of your living space. Box out light fixtures. Cold roofs have insulation between the rafters allowing for ventilation space below your roof deck.

There are different roof decks that require different insulation techniques. 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. The problem arises with moisture. Also the higher the indoor humidity the more insulation is needed to avoid condensation.

Hot roofs are insulated above the rafters. Typically this would be achieved by adding polyiso insulation above the plywood deck. 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. If there is a roof leak the insulation will be damaged by the water leaving you with less insulating value.

The right thickness would need to be calculated to move the dew point above the plywood deck where air infiltration is minimized. T he problem with the insulation against the sheathing expands. Whether or not there is an inner roof lining and the total thickness of the roof structure. The technically correct approach depends on a number of factors.

Unless you re using mineral wool insulation or your fixtures are rated safe for contact with any type of insulation don t allow the material to touch or cover recessed cans or lights from the floor below it s a fire hazard. The ratio of insulation above the roof deck or air permeable insulation below the roof deck is a matter of climate and interior conditions. Insulating the roof is a priority if the ceilings of your home happen to be part of the roof deck as is the case with cathedral ceilings. Add insulation above the roof deck this approach fits current building science thinking in terms of putting the thermal control layer on the outside of the building structure.