Green Building Q&A: Heat Bridge or 3-Dimensional Pressure Boundary
I stumbled on this interesting image a while back. I noticed that the caption refers to "heat bridges from structure and roof fasteners".... The fastener locations are obvious.... But the linear pattern does not look like a structural pattern(series of wood or steel rafters or joists). It looks more like a pattern of rigid insulation and the voids between the insulation. I think the pattern is more likely related to 3-dimensional Air flow as mentioned in this Insight http://www.buildingscience.com/documents/insights/bsi-036-complex-three-... I think what is missing in the photo is an air barrier on the warm side of the insulation.