[Greenbuilding] Cathedral Ceiling & Icynene Insulation

[Alan Abrams]

   Ron--we got approval to do this in Montgomery County, MD back in 2003, and
   it  has  become  our  standard  for stick construction since then, for
   "cathedral" ceilings, fully insulated attics, and flat roofs as well.  I
   believe it is approved by the ICC, too, but i'm at home without a code
   book...

   See:

   http://www.icynene.com/assets/documents/PDFs/Vol12_04_EarthCraft.pdf


    "By its nature, Icynene® requires no ventilation space from
   soffit to ridge, which increases design freedom for both the exterior and
   interior of the house. Icynene® is intended to fill all of the gaps and
   crevices, thus eliminating the need to leave a path for air ventilation
   within the rafters."


   and

   http://www.icynene.com/assets/documents/PDFs/RLS-ICC%20Approves%20Unvented%2
   0Attics.pdf

   Shingle manufacturers will reduce their warranties in some cases without a
   ventilated roof deck, but i suspect this is substantially a canard.

   It's  also advisable to make sure there are no paths from the basement
   through wall cavities into any transitions from wall to ceiling.  to be on
   the  safe  side,  develop  strategies  to prevent the house from being
   depressurized, by bath or kitchen vents, for example.  avoid recessed lights
   in the ceilings like the plague.
   Alan Abrams AIBD
   Abrams Design Build LLC
   202-726-5894 o
   202-291-0626 f
   www.abramsdesignbuild.com
   On Sat May 19 23:40 , "Ron Hays" sent:
   
     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