Wayne Dalton’s Model C-24 provides high strength at an excellent value and features 24-gauge ribbed steel sections available in a variety of sizes and configurations. Unique 2” x 3” box-stile design, plus tongue-and-groove construction, adds vertical stability and strength. Stiles are continuously-bonded to the skin surface with high-strength adhesive, resulting in the strongest possible unit. The surface is ribbed for even more strength. Independent tests show that Model C-24 sectional doors are significantly stronger compared to leading competitors. Optional insulation consists of 1-5/16″ expanded polystyrene which provides an R-value* of up to 7.64 and a U-value as low as 0.13.