Insulating The Roof Deck

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 deck.

For the same reason insulation shouldn t touch the roof s underside. Hot roofsare insulated above the rafters. When installing a foil faced foam board insulation. This construction approach was first used in the 1970s and it has been implemented much more widely since it was first included in the international code council s icc model building code in 2007 irc section 806 4.

The airflow from the soffits to the ridge vent keeps the roof cool and prevents ice dams and the material will block that flow. Rigid foam insulation boards. When installing rigid insulation in an attic to be finished as a living space you must provide a route by which hot air. However it is the most labour intensive and most expensive option.

Insulating the floor and the roof this is certainly the most interesting solution when the attic is also going to be used. In addition to installing the foam board on the underside of the roof deck you can attach it to the bottom edges of the. Staple plastic or foam baffles to the roof sheathing near the eaves to keep the material away. Cold roofshave insulation between the rafters allowing for ventilation space below your roof deck.

Generally more insulation is needed for condensation control in colder climates. Materials commonly used for the insulation of the roof deck include. There are different roof decks that require different insulation techniques. 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.

Install baffles or make sure there s 1 minimum of airspace between the roof deck and insulation. Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls. Typically this would be achieved by adding polyiso insulation above the plywood deck. Also the higher the indoor humidity the more insulation is needed to avoid condensation.