Insulation Above Exposted Roofing

Following ten years of extensive testing isoboard thermal insulation has developed a proven solution to fixing its thermal insulation boards above rafters trusses or beams.

Insulation above exposted roofing. It s perfectly ok to put the ducts in the attic truss space if you want since these ducts are inside the home s thermal envelope. You don t have to build interior soffits. However most cathedral ceilings and low slope flat roofs are insulated roof assemblies. The insulation for exposed rafters is installed on the exterior side of the finish ceiling.

Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation. This is often a layer of tongue and groove boards nailed to the exterior side of the exposed rafters. Find your zone on the map and then use the chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces. You can prevent this by installing foam insulation board against the underside of the roof between the rafters.

High r value unvented roof assemblies will require a proportionally larger amount of insulation above the roof deck for condensation control. If all of your insulation is above the roof sheathing and if you have a roofing membrane above the insulation then you already have an airtight insulated roof assembly. Insulated roof assemblies can be vented or unvented. Generally 40 of the total assembly r value should be above the roof deck.

The exposed edges of the 3 layers of rigid insulation are to be sealed with another layer of membrane. Additionally insulation serves as a way to enhance sound proofing on the uppermost envelop of your house. Box beam gable framing new gable overhang is framed in the form of a box beam hanging off of a new layer of roof plywood roof sheathing cantilevered over the top of the 3 layers of rigid insulation. With this kind of roof the insulation follows the slope of the roof.

Video of the day volume 0. Isoboard thermal insulation fitted as a ceiling following the roofline allowing the opportunity to create additional space or a liveable loft conversion. A roof over a vented unconditioned attic does not need to include any insulation. More insulation is needed above the roof deck in colder climates and where indoor relative humidity is above 35 in winter.