Abstract: The present invention is directed to a corner trim assembly for walls including first and second polymer pieces which are welded together to form an angled joint for slidably receiving trim pieces at the corners of walls without the use of nails, adhesives or other fasteners.

Abstract: A method for positioning a vapor retarder within an insulation system to reduce condensation within the insulation system is provided. The incremental change in temperature per R-value of insulation is calculated by determining the temperature differential between the exterior temperature and the interior temperature and dividing this temperature differential by the R-value of insulation. Various possible temperatures for the vapor retarder within the insulation may be determined using the incremental change in temperature. The R-values of the insulation layers on either side of the vapor retarder may be determined by a condensation potential analysis. Preferably, the vapor retarder is positioned within the insulation system at a location where its temperature remains above the interior dew point temperature in the summer and above the exterior dew point temperature in the winter. An insulation system including a variably positioned vapor retarder is also provided.