Insulation Below Roof Deck

The roof deck is cold wood decks without insulation above them will readily equilibrate to the exterior temperature.

Insulation below roof deck.

This variation on the unvented attic design requires a thermal barrier such as an approved intumescent coating. The ratio of insulation above the roof deck or air permeable insulation below the roof deck is a matter of climate and interior conditions. Gaining in popularity is the design approach of insulating on the underside of the roof deck and leaving the spray foam exposed to the occupants below. Placing a layer of fluffy insulation below the roof deck would needlessly complicate the.

The project is in climate zone 4 seattle area and i want to have an open beam look in the ceiling. Insulation above the roof deck or air vapor impermeable insulation below the roof deck is needed for condensation control in an unvented roof. During cooler night times and in winter periods the deck temperature can then be below the dew point of the interior air. This section outlines the conditions for unvented attic roof assemblies.

With rising heating and cooling. Hence the term cold decks construction materials wood based products absorb moisture. I would use polyiso with a top layer of eps as recommended in your blog post on the topic. The greater your home s thermal resistance factor or r value the more energy efficient it is.

Note that table r806 5 indicates the amount of insulation above the roof deck or air impermeable insulation below the roof deck required for condensation control assuming minimum required total insulation as indicated in section n1102 building thermal envelope. I m considering a roof design that would place all the insulation above the roof deck with no insulation below.