a low - e housewrap having improved energy efficiency protection against air infiltration and moisture build - up in buildings . the aforementioned low - e housewrap material utilizing existing framing openings or without increasing the wall profile of a building . the present invention provides a low - e housewrap material which may be implemented on traditional 2 × 4 framing having r - 15 mass insulation material within existing or newly constructed framing cavities . the material of the present invention also meets requirements for serving as a water resistive barrier as defined by icc ac38 .