The strangest projects tend to be the most fun. Jas salvaged a cat door from another project and asked me to install it in an existing basement window opening. His criteria were a tight fit and easy removal.

My basic frame for the cat door.

I measured the opening within 1/16 inch, then used 1×2 lumber to frame the world’s smallest stud wall. I added an extra stud to the left side to space out the door from an existing window latch. The cat door is shorter than the opening, so I installed it at the bottom of my frame, then closed the gap with a couple more pieces of 1×2. I had to pre-drill all my nail holes to avoid splitting the wood.

In progress. (I wrote the cat’s name above the door for fun.)

A couple finishing touches help the cat door fit snugly in the opening. I used a chisel to carve out a space for that window latch on the left side. Then I ran the right side of the frame through a table saw several times to create a quarter-inch groove that accepts the tongue of the sliding glass window. Installation is easy – just slide the frame into the opening and pull the window tight against it. Sebastian should be pleased.

Cat door installed in the sliding window.