[Greenbuilding] Cathedral Ceiling & Icynene Insulation

[Ron Hays]

I'm building a bathroom addition for a client in Portland, OR with a
cathedral ceiling (3 on 12).  The house is a 1920's bungalow style home and
the client has had the rest of the house in the house insulated with Icynene
foam insulation sprayed between the 2x4 rafters in the attic, eve and
vaulted ceiling areas.  He wants to spray the vaulted ceiling of the shed
dormer addition with Icynene also.  However, the building inspector is
concerned that if the cavity is fully filled and no ventilation beneath the
sheathing the roof will degrade because of heat built up.  I know this is
conventional wisdom.  Is there any recent research that indicates that it is
OK to fully insulate the joist space.

 

Ron Hays

 

Eagle Creek Natural Building