Extending Roof Rafters For Insulation

The outer ends of a roof s rafters the sloped members that give the roof its pitch provide shade divert rain and create soffit space for attic ventilation.

Extending roof rafters for insulation.

Roof insulation configurations for unvented rafter truss assemblies. After a bit more destruction and dust it is time to look at how we increased the rafter depth in preparation for the insulation. Arguably the most popular pitched roof solution installing insulation between and under the rafters uses the depth of the structural timbers to best effect. 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.

The roof rafters are currently about 20 apart made of 2x6 s the house was built in 1915. 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. How to extend rafters. By installing high density 8 inch fiberglass batt insulation the rafters will then meet an r 30 roof insulation standard.

Its versatility is the key to its popularity whether being used to achieve. In finished attic rooms with or without dormer insulate 2a between the studs of knee walls 2b between the studs and rafters of exterior walls and roof 2c and ceilings with cold spaces above. I ve been talking with the gc about approaches to try and increase the depth of the roof rafters to get in more insulation while at the same time allowing a baffle for air flow i have a slate roof. How to install rafter insulation.

Batts between rafters in would require adding ventilation between the insulation roof deck. For instance if the roof has 2 by 6 rafters and you want r 30 insulation which is standard in many communities you can add a 2 by 4 which will give you an 9 inch rafter space. 2d extend insulation into joist space to reduce air flows. An efficient room in a roof in a new build property where over rafter insulation is not desirable.

Almost there with the old fo.