Flat Roof With Exposed Rafters Insulation

Roof insulation configurations for unvented rafter truss assemblies.

Flat roof with exposed rafters insulation.

Safety precautions and mistakes to avoid during garage roof insulation. On top of your roll roofing add several layers of comfortboard rockwool. Warm roof fixings secure insulation above rafters. 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.

If moisture is a major concern you can also install xps rigid insulation which offers superior moisture resistance. It is top quality and the most cost effective product for your flat roof. Isoboard thermal insulation fitted as a ceiling following the roofline allowing the opportunity to create additional space or a liveable loft conversion. The insulation for exposed rafters is installed on the exterior side of the finish ceiling.

You can expect to pay about 55 100 sq ft. Resistance to compression 943 psf osb and then some more roofing. Hack n stack sealed foam board between the rafters would be better since it s at least an air impermeable insulation but even that would require a vent gap below the roof deck to meet code and you d still be under r38 on that 2x6 rafters unless you fattened it out per holladay s recommendation. Breathing roof with low resistance lr underlay with this option insulation fully fills the rafter space without an airspace between the insulation and type lr underlay.

In the case of a cold roof structure the insulation is placed between or between and under the rafters or at ceiling joist level and the roof is ventilated by leaving a 50mm gap above the insulation which vents air to the outside. I ve been toying with this idea for flat roof insulation which will be a bit more expensive but avoids foam of any kind. The levelling tool enables. For a 1 inch board equivalent of 6 r value.

This is often a layer of tongue and groove boards nailed to the exterior side of the exposed rafters. Ibc dictates acceptable placement and composition of roofing materials in chapter 15 but describes required thermal efficiency of the roof in chapter 13 which references the international energy conservation code iecc the minimum required thermal resistance varies. Images courtesy simpson gumpertz heger.