Softwood Window Board Unsorted Redwood is used for sealing the bottom of a window and filling the gap between the window and wall it has been placed in. It allows for the extra use of a window ledge and is easy to cut and install. The unsorted redwood features a larger knot size but is less prone to splitting and cupping. The window board can be painted to any colour and leaves a smooth and even finish. It provides a weatherproof seal that can also help with the insulation.