Can Roxul Comfortboard 80 be installed on roof deck in non-vented assembly 70psf load requirement?
forrestj
| Posted in Green Building Techniques on
Passive house build in Northern California
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Forrest,
Are you planning to install the mineral wool insulation on the exterior side of the roof sheathing or the interior side of the roof sheathing?
1. If you are planning to install mineral wool insulation on the exterior side of the roof sheathing, you should know that (a) This approach is rarely done except on flat (low-slope) roofs, so you will meet resistance from contractors and code officials; and (b) You'll need to talk to an engineer to work out the fastening details and load details.
2. If you are planning to install mineral wool insulation on the interior side of the roof sheathing, you will need to include a ventilation channel between the top of the insulation and the underside of the roof sheathing. An air-permeable insulation like mineral wool cannot be installed between rafters if the assembly is unvented.