Treated C24 KD Regularised Carcassing Timber 47 x 50mm is a structural timber, used for stud walls, roof & floor joists, and structural joinery. C24 grade has fewer defects and knots than C16, so is stronger with a higher point load. It is machined to have rounded edges, smooth faces and sides, for a more uniformed piece of timber. It is also kiln dried to reduce moisture content and increase the strength and stability, and is pressure treated with preservatives to increase resistance to rotting.