Do I need an air barrier


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Old 11-06-18, 01:39 PM
J
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Do I need an air barrier

Iíve just moved into a home one mile from the ocean on the NC/SC border. It has a covered porch that was glassed in by a former owner. It is under the whole house roof. I added an AC/heat pump self contained unit so it can be used all year. The windows and door are insulated glass. It was a professional job well done. It opens to the house with French doors we keep open 24/7. However they did not insulate it or intend for it to be opened to the house year around. I insulated the floor with rigid and caulked the seams. The ceiling is vinyl with slotted vents in every third section much like soffit covering. There is about 6Ē of fiberglass insulation in the attic over this partially vented ceiling. I assume I need to do something about this venting as I am likely losing my conditioned air through this venting.

I cannot easily drop or remove this vinyl ceiling to replace the vented panels. I can access them in the attic by lifting the fiberglass insulation. What is the preferred way to solve this venting issue? Do I remove the fiberglass and put 6mil plastic over these vented sections and then put the insulation back? Or, can I add another layer of insulation over the top going in a perpendicular direction and forget the vents are there? Do I use faced or unfaced fiberglass? Do I use rigid and seal the joints? Or, do I just not worry about it?

I want to do what would be most efficient to keep my energy costs down and control humidity. But I donít want to spend time and money for a minimal difference.

Suggestions please.
 
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Old 11-06-18, 02:11 PM
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I cannot easily drop or remove this vinyl ceiling
Pretty sure you can. Replacing the ceiling with something solid would be good. Otherwise sheet the top of the joists with rigid foam.
 
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Old 11-06-18, 03:53 PM
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It sounds like you have vinyl soffit. There is a special tool (a flat blade screwdriver sometimes works) that you shove into the joint between panels and you can unhook them. Then you pull the nails or remove the screws and can take the vinyl down strip by strip. This method does not damage the panels so they can be re-installed.

Once you have the panels down I would put up a house wrap like Tyvek. This will block air movement but it will let water vapor pass through which should help your heating and air conditioning. And, while you have the ceiling down it's a good time to add more insulation.
 
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Old 11-06-18, 04:24 PM
J
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I will look into removing the vinyl. Although I would rather solve this from above. It is now a nicely finished room with trim around the perimeter. I am reluctant to mess with what looks so nice. So rigid above the ceiling joists would be an acceptable fix?
 
 

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