vapor retarder การใช้

Cover the ground with a vapor retarder of six millimeter polyethylene film.
So, for example, when insulating an attic floor, the vapor-retarder faces down . ( A vapor retarder prevents water vapor from condensing inside the insulation .)
In areas below foundation level ( or, subgrade areas ), particularly those formed in concrete, vapor retarder placement can be problematic, as moisture infiltration from capillary action can exceed water vapor movement outward through framed and insulated walls.
Another approach is to use the 1 / 3 to 2 / 3 method mentioned above that is, to install a vapor retarder on the inside of the existing wall ( if there isn't one there already ) and add insulation and support structure to the inside.