Cat Door for Sliding Window

As part of a project to build a window box catio (Cat Patio), I needed a cat door that could be installed in a sliding window. I was concerned about cost, durability, appearance, and the long-term availability of replacement parts. Unfortunately, the selection was limited. I therefore decided that a better option would be to adapt a cat door intended for installation in a door or wall.

I selected the PetSafe Large Plastic Cat Door, although their Medium Plastic Cat Door would have been large enough for our current cats. PetSafe is an established pet product supplier, and they offer replacement parts, including PetSafe Replacement Flap for Large Plastic Cat Door.

I decided to mount the cat door in clear acrylic. Clear acrylic is well suited for use in a sliding window, since it is resistant to cold, heat, water, and UV light. Clear acrylic is readily available from TAP Plastics, and they will cut the acrylic to size.

I removed the sliding window and measured its height and thickness. My window was ½ inch thick and 34 inches tall. Here is the diagram that I provided to TAP Plastics. You will need to adjust this diagram based upon the height of your window, and the size of the cutout required for your cat door. I recommend a minimum of 2 inches on each side and on the top and bottom of the cutout for durability. My local TAP Plastics store charged me $90.45 for the acrylic, plus a labor charge of $15 for the cutout, for a total of $105.45. Since I paid $59.95 for the PetSafe Door, my total cost was only $165.40.