Replies

1. 
   BillHartmann | May 25, 2006 08:17pm | #1

   Tyvek is not a vapor barrier. In fact it is designed to allow water vapor to pass through.

   What is your climate? What is the total cross section of the wall including insulation and the type of insulation?

1. 
   Michael1955 | May 25, 2006 09:06pm | #2

   Thank you for your correction.

   Tyvek weather-resisitant barrier would have been more accurate.

   The climate is central texas, The walls are 2x4 construction with Fiberglass kraft faced insulation.

   My question is; Since the foil board is already faced to prevent thermal drift of the gases trapped during the manufacturing process, is there a need for an additional weather / vapor / air barrier.

   Thanks

   Michael

1. 
   DanH | May 25, 2006 10:42pm | #3

   Is this foil-faced foam sheathing, or the foil-faced 1/4" thick stuff used under vinyl siding? The latter is perfed to allow moisture/air to get through and won't provide a reliable weather barrier.I would guess that the foil-faced foam sheathing would be reasonably reliable as a weather (and vapor) barrier if the joints are carefully taped, and flashing is properly applied.In your climate cold-weather condensation isn't a major concern, and the foil-faced foam would probably provide a desireable cooling-season outer vapor barrier.

   If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison

2. 
   Piffin | May 26, 2006 01:46am | #4

   tape the seams and foam any gaps and you won't need an added layer 

    

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