The present invention provides methacrylic acid polymer modified aqueous urea formaldehyde resin (UF resin) binder compositions useful in making a treated glass mat, e.g. for roofing shingles, wherein the methacrylic acid polymer comprises the reaction product of at least 50 wt. %, based on the total weight of monomers used to make the methacrylic acid polymer, of methacrylic acid or its salts, or mixtures thereof, a water-soluble phosphorous or sulfur containing compound and the remainder of a carboxylic acid group containing monomer, such as acrylic acid. The methacrylic acid polymers have at least one of a phosphite group, hypophosphite group, phosphinate group, diphosphinate group, and/or sulfonate group and enable modified UF resins to have early strength development even when the binder compositions comprise from 0.1 to less than 5 wt. % of the polymer modifier, based on total solids of the UF resin and the polymer modifier.