Insulation Below Roof Deck

Insulation above the roof deck or air vapor impermeable insulation below the roof deck is needed for condensation control in an unvented roof.

Insulation below roof deck.

The roof deck is cold wood decks without insulation above them will readily equilibrate to the exterior temperature. I would use polyiso with a top layer of eps as recommended in your blog post on the topic. Placing a layer of fluffy insulation below the roof deck would needlessly complicate the. I m considering a roof design that would place all the insulation above the roof deck with no insulation below.

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. The ratio of insulation above the roof deck or air permeable insulation below the roof deck is a matter of climate and interior conditions. The project is in climate zone 4 seattle area and i want to have an open beam look in the ceiling. How to attach rigid insulation on the underside of the roof deck.

07 22 00 roof and deck insulation. This section outlines the conditions for unvented attic roof assemblies. During cooler night times and in winter periods the deck temperature can then be below the dew point of the interior air. This variation on the unvented attic design requires a thermal barrier such as an approved intumescent coating.

With rising heating and cooling. Hence the term cold decks construction materials wood based products absorb moisture.