Xps On Roof Decking Above Vented Roof

At an interior temp of 70f and an outdoor temp of 25f the roof deck is colder about 40 of the temperature difference above the outdoor temp or about 43f.

Xps on roof decking above vented roof.

Back in the 1960 s through the 1980 s vented metal deck was used on the majority of steel frame roof decking for commercial and industrial buildings. History on vented metal deck. Vent the roof deck. The system shown below is the elevated batten system made by boral roofing which uses treated 1 by 2s with high grade plastic pads a vented eave riser flashing and vented weather blocking at the ridge.

Enhancing roofing material life span by reducing sheathing temperature. Owens corning insulation products help improve thermal performance and control moisture in commercial institutional and. High r value unvented roof assemblies will require a proportionally larger amount of insulation above the roof deck for condensation control. The addition of vented eave riser flashing and ridge ventilation completes an energy saving asv system.

More insulation is needed above the roof deck in colder climates and where indoor relative humidity is above 35 in winter. When roofs leak the intruding water often damages the insulation below the membrane. There are traditionally four main reasons for venting a roof. Controlling ice damming by keeping the roof cold.

Xps and the white membrane installed directly to the steel roof deck combine to create a highly sustainable roofing system. In order to understand what the purpose of vented metal deck is we need to take a look back in history to when vented metal roof deck was necessary. The planned roof stackup from inside to outside. If the attic space is going to be conditioned either for living or mechanical purposes or if a home design calls for a vaulted ceiling provision r806 3 in the international residential code calls for the roof deck above the space to be vented continuously from the eave to the ridge.

Foamular xps roof insulation for commercial buildings page 5 foamular xps roof insulation for commercial buildings foamular xps insulation is a rigid foam insulation which meets the needs of today s design professionals for a truly sustainable insulation product. Unvented roofs vented roof. Generally 40 of the total assembly r value should be above the roof deck. With an outdoor temp of 25f and roof deck temp of 43f the mean temp through the foam is now about 34f 1c.

Xps roof insulation types x 15 psi iv 25 psi and v 100 psi are commonly used with mechanically attached cool white roofing membranes and a simple slip sheet. Exposed tji rafters 24 oc 1 2 plywood sheathing w h clips fully adhered wrb continuous with wall wrb 2 layers of 3 of roxul comfortboard r 24 total 2x4 purlins parallel to ridge connected to rafters via long screws these purlins. I m building an unconditioned workshop with a cathedral ceiling i e no attic under a shed roof.