The article presents the results of an investigation of composites based on manufactured samples of fiberglass metalized with a submicron film made of brass, neusilber and non-magnetic SS304 stainless steel. It was found that, due to their characteristics, the samples of metallized fiberglass are an effective electromagnetic wave-absorbing filler for various building and construction materials; The developed metallized fiberglass samples are also useful for the creation of EMI-shielding building materials for protection from microwave radiation. With an increase in the proportion of metalized glass fiber, the electromagnetic shielding of the studied composites increases systematically. It is determined that at a concentration of 5 wt.% brass-metallized glass fiber, a test composite material with a thickness of 250 mm is able to shield up to 13.7 and 21.2 dB in the 4G and 5G ranges of cellular communication electromagnetic waves, respectively.