Stop your cat from opening doors by kitty-proofing your latches, making doorways unappealing and using non-harmful repellents.
Cats and Door Training
Training your cat away from pushing open doors can serve several useful purposes. Stopping access to the outdoors can help keep your cat safe from predators and cars; keeping your cat from bedrooms can help reduce human allergies and ensure a good night's rest; and keeping your kitty out of pantries, basements and garages can prevent injury or accidental ingestion of harmful substances.
Check Your Latches
Make it impossible for your cat to push open doors by inspecting door handles and latches. Changes in the weather can cause wooden doors to expand or contract throughout the year, sometimes to the point that latches don't catch the way they should. Older doors or faulty doorknobs can also become worn with age and the closing mechanisms can slip, making it easy for your cat to bump or push the door open. Combat these problems by replacing malfunctioning handles or by adding latch hooks to doors.
Steer your cat clear of off-limit doors by placing double-sided sticky tape on the floor in front of the door, or laying down plastic floor matting with the nubby side up. Your cat won't like the feel of these surfaces and will learn to stay away. Another option is to spray doorways with a citrus cat-repelling spray. Vinegar and coffee grounds will also keep your kitty clear of doorways, but the mess and smell makes it a last-resort option.
Squirt Guns and Penny Cans
Fill a can or water bottle with pennies or load a spray bottle or squirt gun with water. When you catch your cat in the act of trying to open a door, gently spray her or toss the can or bottle in her direction. The sound and feel will irritate but not hurt her. Try to stay out of sight when using these methods so your cat doesn't associate you with the ruckus.