DETAILS, FICTION AND ท่อน้ำฝน

Use wooden stakes and Mason’s line or chalk line to create a square or rectangular shape round the marked space. Ensure the formwork is amount and secure. Even though building the formwork, make allowance to the slope toward the center on the drain.อ้างอิง-ภาพ : สำนักงานทรัพยากรน้ำแห�