Glass mats for use in building construction are provided. The mats include chopped glass fibers and a formaldehyde-free-curable binder disposed on the glass fibers. The binder includes a binder selected from polyorganic acid-polyol, starch grafted acrylic styrene and acrylic modified polyvinyl acetate, for example, containing a sufficient amount of a hydrophobic additive to improve the hot wet retention of the mat after five minutes of exposure to 80.degree. C. water by at least about 5%.