Siberian larch decking board (terrace board) is a planed, profiled lumber for constructing open-air decks exposed to precipitation, UV radiation, and temperature fluctuations. Profiles: smooth 'deck' and ribbed 'anti-slip' with non-slip grooves. Thickness 27–35 mm, width 90–142 mm, length 2000–6000 mm. Kiln-dried to 10–12% moisture content. Underside features stress-relief grooves. Larch is the ideal species for decking: natural resistance to rot and insects (durability class 3 per EN 350), hardness, wear resistance. Does not require antiseptic impregnation. Recommended treatment with decking oil (Osmo, Tikkurila) for UV protection. Service life outdoors: 25–50 years. Installation on joists with a 5 mm gap between boards for water drainage. Applications: terraces, verandas, pool areas, piers, docks, embankments, garden paths, balconies. Competes with WPC (wood-plastic composite) and tropical hardwoods (teak, IPE). GOST 8242-88. Larch decking vs. WPC: natural wood feels warmer, does not heat up to scorching temperatures in the sun (unlike WPC), possesses natural grain beauty. WPC requires no oiling but fades and warps when heated. Installation: larch joists 45x70 mm, spacing 40–50 cm. Fasteners: hidden (Klyuch, Cobra, Gvozdyok) or open (pre-drilled screws). Gap between boards 5–7 mm for drainage. Export documentation: phytosanitary certificate, certificate of origin. Packaging: shrink wrap, cardboard corner protectors.