Birch plywood grade FSF is a multi-layer sheet material with increased moisture resistance, made from birch veneer bonded with phenol-formaldehyde resin. Its tensile and bending strength is higher than that of FC plywood. It does not deform upon direct contact with water. Service life exceeds 20 years. Density 660–750 kg/m³. Birch FSF plywood is approximately 20% stronger than softwood plywood. Formats: 1220×2440, 1250×2500, 1500×3000 mm. Thickness: 4–40 mm. Grades: I/II, II/III, II/IV, III/IV, IV/IV. GOST 3916.1-2018. Applications: exterior construction work, formwork systems, roofing, van cladding (automotive), wagon building, shipbuilding, advertising boards, sports grounds. Not recommended for residential interiors due to phenol content. Major Russian producers (Sveza, etc.) ensure worldwide export supplies. Production: technology similar to FC, but with phenol-formaldehyde adhesive — hot pressing at 140–150°C. Phenolic resin provides water resistance but emits formaldehyde (class E1 — ≤10 mg/100 g). Export documentation: phytosanitary certificate, certificate of origin, CE certificate. Packaging: pallets, strapping tape. Shipment: containers, railway platforms. Birch FSF is 20% stronger than softwood: tensile strength ≥40 MPa. Density 660–750 kg/m³ — heavier than softwood but stiffer.