Insulation Below Roof Deck

This section outlines the conditions for unvented attic roof assemblies.

Insulation below roof deck.

The greater your home s thermal resistance factor or r value the more energy efficient it is. Insulation above the roof deck or air vapor impermeable insulation below the roof deck is needed for condensation control in an unvented roof. 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.

The project is in climate zone 4 seattle area and i want to have an open beam look in the ceiling. This variation on the unvented attic design requires a thermal barrier such as an approved intumescent coating. 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.

During cooler night times and in winter periods the deck temperature can then be below the dew point of the interior air. I m considering a roof design that would place all the insulation above the roof deck with no insulation below. Below you will find links to company and product information for manufacturers and suppliers listed in the roof and deck insulation section of sweets. 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.

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