Replies

1. 
   Piffin | Jan 16, 2005 08:55pm | #1

   A lot of people folow a theory that blowing dens packed cells into older walls especially is fine without a VB, because the vapour transmission is slowed in such a dense medium.

   I'm not so sure that I agree, because of having worked on older homes where the cellulose held moisture and rot increased, though this may be more from exterior leaks than from interior moiisture.

   Do you have a VB on the exterior too? having one threre and not on the inside is probably worse than not having one at all because it will trap moisture, not allowing it to pass all the way through.

    

    

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1. 
   stevebell151 | Jan 16, 2005 10:51pm | #2

   I do have tyvek house wrap on the outside of my house! I would think that with plastic behind the sheetrock that the wall could'nt breathe , trapping the moisture in the insulation. Where does the water come from ? Does it come from the hot air hitting the cold air , or from moisture in the house going through the paint and the sheetrock? If it actually comes from the hot and cold air hitting it does'nt make sense that plastic would prevent it.

1. 
   brownbagg | Jan 16, 2005 10:56pm | #3

   just paint with a vapor barrier type paint and fotget about it

2. 
   Piffin | Jan 16, 2005 11:49pm | #4

   Tyvek is not a VB. It will allow moisture to migrate through it.Moisture in the interior air space comes from normal life.
   In abny new house, the concrete, lumber, and paint are still drying out for a couple of years.
   Then, each person living there will perspire and expire ( breathe on a piece of glass or mirror to see the moisture you expire each and every time you exhale) a half gallon of water a day. And doon't forget that cooking and showers make a lot of moisture into the air too.But BB is probably right, an oil based or specially formulated VB paint will help and any other moisturte making it into the cells will dry again since you have no materials to trap it. Just make sure the windows etc are properly flashed and caulked to keep water out from wind driven rain and you should be able to sleep well at night. 

    

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2. 
   DanH | Jan 17, 2005 12:29am | #5

   You should have a vapor barrier. If it's too late to install one, paint with a vapor barrier paint.