Cats fall at home in predictable places: a window pushed wider than expected during a chase after a fly, a balcony rail walked once too often, a wardrobe top reached by a jump that fell short on the way down. She survives heights that would injure other animals often enough to feed a myth, but vets treat fall injuries regularly, and the myth is no protection for the individual cat. Proofing works by removing the fall, breaking the fall or shortening the fall, in that order of preference.
Windows: protection made for cats
Every window that opens needs a screen or net made for cats, including small bathroom windows and windows in rooms she rarely enters, because doors get left open and a cat's map of the house is larger than yours. Ordinary insect mesh does not hold a cat's weight: it is designed to flex against insects, and a cat leaning, pouncing or scrambling at it can push fixings out or tear straight through. Cat-rated screens use stronger mesh in a frame fixed to the window surround, and cat nets are tensioned or screwed across the opening so the whole surface resists a full-body impact.
Check the fitting, not the label. Every edge should be secured with no loose corner a paw can work at, opening windows should still close and latch without trapping the net, and tilt-and-turn windows need protection across the side gap they create when tilted, since that wedge traps and drops cats who try to climb through it. Re-check fixings after cleaning or storms, and treat any screen she has damaged as failed equipment to replace, not a warning she will respect next time.
Balconies: net the whole opening
A balcony needs netting or rigid panels across its full face, starting at floor level and rising past the top rail to the balcony above or a fitted frame where the fall continues higher. Gaps at the sides, under the rail or between rail and net are the usual failure points, because a cat tests edges, not centres. Fix the net under tension so it cannot billow into a pocket she can climb, and check that the door onto the balcony is treated like an outside door by everyone in the house: closed, latched and never propped open on a hot day while she is loose indoors.
Remove launch furniture from beside the rail. A chair or storage box next to netting invites climbing to the one height where a slip carries her over or through a weakened top edge, so keep the balcony floor plan low and give her a permitted lookout, a cushion or shelf at a height where a fall lands on the balcony itself.
High furniture and landing zones
Anchor tall bookcases, wardrobes and cat trees to the wall so a cat who falls, jumps or scrambles cannot pull the furniture down after her. Wobble is a warning sign in a cat tree: a tree that rocks during a leap trains a bad landing and can tip entirely under a running jump.
Then plan the landings. Arrange shelves, steps and furniture so routes up and down run in stages, with each descent a short hop onto a stable, soft or grippy surface rather than a long drop onto polished floor. Put rugs or mats under favourite high spots, keep the floor beneath window perches and wardrobe routes clear of hard-edged objects, and provide a deliberate staircase of furniture for an older or less agile cat instead of expecting the athletic route of her youth to serve her forever.
If prevention ever fails and she gets out or is found injured after a fall, she needs a vet promptly even when she walks away apparently unhurt, because internal injuries declare themselves late. Lost Pet Alert System, ready in KinsLe, remains the fallback after a fall or escape: owners nearby get notified, and whoever finds her can reach you by direct message.