Making a Cat Window Sill Shelf.

Making a Cat Window Sill Shelf. The average window sill is too narrow for a cat to lay on. You want to make the window sill a few inches wider so a cat can fit on the window sill easily. To make the window sill wider for a cat, I used two 2 by 2 inch pieces or pressure- treated wood and then screwed them to the side of the window sill to make it about 3 inches wider. Then for a strong, easy to clean and waterproof cover for the window sill, I cut some stone tile to size and then glued the stone tile over the window sill to make a strong, water-proof and easy to clean place for the cats to lay-down by the window. The window sill is not about 6 inches wide and has plenty of room for the cats to lay down on. Even if you do not have a cat, making the window sill wider and using stone tile on top of it makes the window sill much more useful for plants, since it is wider and waterproof.