How to Build a Cat Shelf That Fits Over a Windowsill

If your cat likes windows and you're handy with a screwdriver, this window shelf should make you both happy. Not only does it give your cat a place to view the outdoors, but it does so without the necessity of drilling into your home.

Things You'll Need

  • Board, 12 by 18 by 3/4 inch Two 1- to 1 1/2-inch L-brackets (See "Preparation" section to figure exact size.) Two L-brackets with a short side (4 to 6 inches) and a long side (6 to 8 inches) Two small nuts and bolts to fit the larger brackets Four 3/4-inch wood screws
Show More

Instructions

  1. Preparation

    • 1

      Choose the right window: A double-hung window (one that slides up and down) that provides access to the windowsill can accommodate a large shelf that needs no screws or nails to be secure. Older windows work best, as newer ones close too tight to allow brackets to slide between the window sash and the sill.

    • 2

      Measure the distance from the window ledge inside the window to the top of the window sill and add three-quarters of an inch. This is the length of the small L-brackets you will need.

    • 3

      Small brackets are usually less than one-sixteenth-inch wide, but some modern windows offer no space between the sash and the sill. Before continuing, lay the chosen brackets in the window against the sill, and lower the window onto the brackets. If you cannot close the window, this shelf design will not work.

    • 4

      Note where the brackets lie against the end of the shelf. Lower them a sixteenth of an inch and attach them using wood screws. Place them about a a quarter of the distance from the ends of the shelf (4 1/2 inches, if using an 18-inch board).

    • 5

      Connect the long end of one of the larger brackets to the short end of the other, using nuts and bolts. You will have what amounts to a wide U-bolt with one stem shorter than the other.

    Installation

    • 6

      Set the shelf in the window, and lower the window onto the brackets. Already, with the window locked from opening, you have a sturdy shelf that will hold a lightweight animal. To make the shelf sturdier, continue reading.

    • 7

      While holding the shelf level, place the short end of the joined brackets at the midpoint of the long dimension of the shelf. Move the joined bracket until the tip of the longer stem touches the wall. On the shelf bottom, mark where the screw holes align.

    • 8

      Remove the shelf from the window and attach the joined bracket to it using 3/4-inch screws. Raise window, insert shelf, lower window. The shelf should sit securely.