attic/wall insulation question

jasonr26

All,

I have some questions about insulation if anyone would be gracious enough to offer some assistance. Just a little background, I will be assiting with the new contruction of my home, which is in Alabama. We have mild winters and hot summers and it is usually very humid most of the year. I hope to do mych of the insulating and wanted to know how the vapor barrier needed to be installed? In the walls, I will probably be using an r-13. Will the paper side need to face toward the inside of the house? Also, in the attic (I will be blowing in the recycled newpaper/phonebook insulation), is it best to install some type of plastic sheeting under the ceiling joist before the sheetrock below is installed? it a vapor barrier even needed?

Thanks,
Jason

redline

The paper side (vapor barrier) of the insulation needs to face the "heated" space.
It would save time to install the vapor barrier before the drywall is installed for the attic.

manhattan42

According to Energy Codes, warm, humid locations like Alabama require no vapor retarders in walls or ceilings, or when they are used, will be placed on the unheated side of wall and ceiling assemblies.

Vented attics also require no vapor retarders.

Vapor retarders are also usually not required when using blown cellulose. Check your manufacturer's installation instructions.

For the right answer for your location, contact your building code officials.