The complete guide
Choosing a cat proof window screen
Which size covers your window?
This screen covers an opening up to 100 cm wide and 100 cm tall, which suits a standard single window or a casement sash. You cut it down, so order above your opening rather than below it and trim the rest away.
Measure the frame recess rather than the glass, because the tape goes on the flat face of the frame around the opening.
What makes a cat screen different
The name is doing a lot of work. A cat screen is a protective screen for cats, and the difference from an ordinary insect screen is entirely in the mesh.
Standard insect screen is thin fibreglass. It's made to stop mosquitoes, and it does that well. Put a cat against it and you have days, not seasons. Pet mesh is woven 10 x 16 from heavy-duty vinyl-coated polyester yarn. It is thicker, it is tougher, and claws do not pierce it or drag it apart.
That buys you two things at once: the cat stays in, and the insects stay out.
Why it matters
Cats are curious and, for all their balance, clumsy. They nap in odd places, they love height, and an open window is an open invitation onto the ledge. They do fall, and landing on their feet is not the same as landing unhurt.
Without a screen the choice is a shut window and an overheated room, or an open one and a risk you think about all day. This removes the choice.
Fitting it
Wipe the frame face clean and dry it, because the adhesive gets one go. Run the hook-and-loop tape around the opening, lay the screen over it, cut it to size with a blade or strong scissors, and press the velcro edge down firmly all the way round.
Press it properly. The tape grips along the whole edge rather than at a few points, and that even grip is what takes the load when a cat leans on it.
Fifteen minutes covers the first window. Nothing is drilled, so a rental is fine and the frame is untouched when it comes off.
Looking after it
Take the screen down and wash it in warm soapy water when it needs it, then let it dry fully before it goes back up. Keep hair and dust off the tape so it keeps its grip.
Most cat owners leave these up all year rather than running them seasonally, which is the sensible approach: the window gets used more, and there is never a week where the screen is in a cupboard and the window is open.