Roof Deck Insulation Foam

Gaco is a best in class provider of silicone roof coating systems waterproofing and insulation solutions for commercial and residential buildings.
Roof deck insulation foam. As air impermeable insulation spray foam insulation can be used in such applications. It typically has 3 variations. High efficiency attic insulation helps provide added thermal protection lessens wasted energy and increases enhanced comfort and quiet. Shown to withstand delamination deterioration warping and jobsite damage more effectively than other roofing membrane substrates such as paper faced gypsum board fiber board and perlite insulation.
The ratio of insulation above the roof deck or air permeable insulation below the roof deck is a matter of climate and interior conditions. Bare foam board one sided sheathing board or double sided which is also reference as structural insulated panels. A sealed and insulated roof deck can t dry inward to the attic if the roofing happens to let water. Spray foam insulation applied on the underside of the roof deck in cold climate commercial buildings allows for a significant reduction in condensation potential particularly compared to interior air permeable batt systems.
And vented or unvented attics that are insulated above the roof deck with rigid foam. Lstiburek takes blame for bad language. Applying closed cell spray insulation to the underside of a roof deck at the sheathing to truss connection can double or triple the strength of the assembly boosting the roof sheathing s resistance to wind uplift in a hurricane. Unvented attics that are insulated on the underside of the roof deck with blown spray foam.
But foam also traps moisture in the roof in case of a leak. The later is used in new construction as the interior board serves as an inner wall. Rigid foam board is just above the roof deck or an exterior insulation option. 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 amount of closed cell spray foam or rigid insulation is somewhere between 20 to 50 of the r value of the overall cavity insulation depending on your climate zone. Most unvented attics incorporate spray polyurethane foam spf on the underside of the roof deck and attic walls. Also the higher the indoor humidity the more insulation is needed to avoid condensation. Generally more insulation is needed for condensation control in colder climates.
Moisture generated indoors or that infiltrates into the home is responsible for the bulk of the moisture in an attic insulated with spray foam on the underside of the roof sheathing.