The application dimension of Purlin segmentation distinguishes four primary end‑use categories: residential, commercial, industrial, and infrastructure. Residential projects, which include single‑family homes and low‑rise apartments, dominate the market due to widespread adoption of lightweight roofing systems; they account for roughly 40 % of total purlin revenue. Commercial applications—office blocks, retail centers, and mixed‑use complexes—contribute about 35 % as developers prioritize speed of construction and material efficiency. Industrial usage, encompassing factories, warehouses, and cold‑storage facilities, represents 15 % of the market, driven by the need for long‑span roofing with high load‑bearing capacity. Infrastructure projects, such as bridges, stadiums, and public shelters, occupy the remaining 10 %, reflecting specialized design requirements and lower volume. Collectively, these application segments shape the overall market size by allocating demand across construction typologies, and the proportional weights are reflected in the accompanying pie‑chart.