Insulation, Radiant and Vapor Barriers - Paper or plastic?
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BrianNH
03-07-09, 12:46 PM
One of my 1st jobs when I was younger was a bagger at a grocery store. However, now that question brings on a whole new meaning to me.
For the short version of the question; should I put a continuous vapor barrier (poly) over the entire wall on each floor or should I use kraft faced paper?
The detailed view:
I have a 10 year old colonial in New Hampshire. Noticed condensation build up in the attic on the gable end walls (none on the underside of the roof sheeting) which appeared to have run down the inside of the exterior walls all the way to the 1st floor. After removing the 2nd floor walls (drywall and inslulation) I noticed the vapor barrier was not installed all the way down to the floor. There was about 10-12 inches of it missing.
Walls were wet only on the inside of the OSB. Insulation was not soaked, rather it had some damp spots where it stuck to the OSB sheeting, but mostly dry.
I have vinyl siding, owens corning housewrap, osb sheeting, fiberglass R19 unfaced insulation, with 2X6 - 24" OC exterior walls. On the 1st floor there was NO vapor barrier at all. Just insulation. Forced hot air heat and central air in the summer. Humidity levels between 20-30% in the winter. We did run a hunmifier in my sons bedroom at night but I don't think the levels got to much more then 35%. We did avoid turning on the bathroom vent fan to try to keep some moisture in the air. So dry though that I have more static than humidity in the winter.
Replaced some plywood and washed / cleaned the rest drying it down below 14% moisture levels. Plan is to put new unfaced insulation in and put a complete poly vapor barrier. I have not ruled out kraft faced paper w/o poly but seems if this was a condensation issue from inside the house the poly would be better.
I am however still trying to make sense of all of this as to the cause and prevent it from happening again. And more over, not make it worst if I try to solve it another way by varying from the sloppy design that was there. Still not sure why they would have skipped not putting a vapor barrier on the 1st floor other than being cheap.
I suspect that the attic ridge vent was covered for a long time with snow and the sofit and proper vents were not drawing any fresh air through. However, it could be anything.
If anyone has any ideas or suggestions, I am close to putting the walls back up. I have been to many web sites and read many reports on vapor diffusion, the stack effect, and all that fun stuff. Still kind of baffled at the cause of this and that I'm solving it 100% correctly.
For the short version of the question; should I put a continuous vapor barrier (poly) over the entire wall on each floor or should I use kraft faced paper?
The detailed view:
I have a 10 year old colonial in New Hampshire. Noticed condensation build up in the attic on the gable end walls (none on the underside of the roof sheeting) which appeared to have run down the inside of the exterior walls all the way to the 1st floor. After removing the 2nd floor walls (drywall and inslulation) I noticed the vapor barrier was not installed all the way down to the floor. There was about 10-12 inches of it missing.
Walls were wet only on the inside of the OSB. Insulation was not soaked, rather it had some damp spots where it stuck to the OSB sheeting, but mostly dry.
I have vinyl siding, owens corning housewrap, osb sheeting, fiberglass R19 unfaced insulation, with 2X6 - 24" OC exterior walls. On the 1st floor there was NO vapor barrier at all. Just insulation. Forced hot air heat and central air in the summer. Humidity levels between 20-30% in the winter. We did run a hunmifier in my sons bedroom at night but I don't think the levels got to much more then 35%. We did avoid turning on the bathroom vent fan to try to keep some moisture in the air. So dry though that I have more static than humidity in the winter.
Replaced some plywood and washed / cleaned the rest drying it down below 14% moisture levels. Plan is to put new unfaced insulation in and put a complete poly vapor barrier. I have not ruled out kraft faced paper w/o poly but seems if this was a condensation issue from inside the house the poly would be better.
I am however still trying to make sense of all of this as to the cause and prevent it from happening again. And more over, not make it worst if I try to solve it another way by varying from the sloppy design that was there. Still not sure why they would have skipped not putting a vapor barrier on the 1st floor other than being cheap.
I suspect that the attic ridge vent was covered for a long time with snow and the sofit and proper vents were not drawing any fresh air through. However, it could be anything.
If anyone has any ideas or suggestions, I am close to putting the walls back up. I have been to many web sites and read many reports on vapor diffusion, the stack effect, and all that fun stuff. Still kind of baffled at the cause of this and that I'm solving it 100% correctly.
Bud9051
03-08-09, 05:49 AM
Hi Brian, If I assume the NH is up north then you will need the VB. Your reading should have given you the info, but I will review it again. All homes breathe, stack effect, heat cycling, combustion air, exhaust fans, dryer, and general leaks. Half of the air flow is out and the other half is in. Electrical boxes, around doors and windows, and under the bottom of your sheetrock up between the rock and the framing are just a few of the leaks. Once air is inside a wall cavity, it can go just about anywhere as rock and sheathing are almost never sealed to the framing. All basic and I'm sure you have read.
So here are some problems. If they skipped the areas you found, chances are they skipped on other walls. Moisture can pass directly through sheetrock so a covering of oil based paint or vinyl wall paper can act as a VB.
Here are a couple more links for more reading. Good luck.
EERE Consumer's Guide: Vapor Barriers or Vapor Diffusion Retarders (http://apps1.eere.energy.gov/consumer/your_home/insulation_airsealing/index.cfm/mytopic=11810)
BSD-106: Understanding Vapor Barriers — (http://www.buildingscience.com/documents/digests/bsd-106-understanding-vapor-barriers/?full_view=1)
Welcome To Home Energy Magazine Online (http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/95/950309.html)
Bud
So here are some problems. If they skipped the areas you found, chances are they skipped on other walls. Moisture can pass directly through sheetrock so a covering of oil based paint or vinyl wall paper can act as a VB.
Here are a couple more links for more reading. Good luck.
EERE Consumer's Guide: Vapor Barriers or Vapor Diffusion Retarders (http://apps1.eere.energy.gov/consumer/your_home/insulation_airsealing/index.cfm/mytopic=11810)
BSD-106: Understanding Vapor Barriers — (http://www.buildingscience.com/documents/digests/bsd-106-understanding-vapor-barriers/?full_view=1)
Welcome To Home Energy Magazine Online (http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/95/950309.html)
Bud