If you have ever come home to shredded upholstery, it is tempting to read it as spite. It isn't. Scratching is one of the few behaviours a cat will perform whether or not anyone is watching, whether or not they are happy, and whether or not you have provided somewhere appropriate to do it.
Understanding why makes the problem solvable, because the goal is not to stop the behaviour. The goal is to move it.
What scratching actually does
Claw maintenance. Cat claws grow in layers. The outer sheath wears out and needs to come off, revealing the sharper claw underneath. Scratching against a rough surface is how that sheath gets stripped. You will sometimes find what look like whole shed claws near a scratching post, those are the empty husks, not broken nails.
Stretching. Watch a cat use a tall post and you will see the whole body extend: front legs up, spine long, shoulders and back engaged. It is closer to a full-body stretch than a hand exercise. This is why post height matters so much.
Scent marking. Cats have scent glands in their paw pads. Scratching leaves a chemical signature that other cats can read, layered on top of the visible marks.
Visual marking. The shredded surface itself is the message. It says a cat lives here and uses this space.
The last two explain something that frustrates people: cats often scratch most enthusiastically in the busiest part of the house, on the most prominent piece of furniture. That is not bad luck. A marker only works where it will be seen.
Why punishment fails
None of the four drives above go away when you shout. The cat learns not to scratch while you are in the room, which is not the same thing, and it does not learn where else to go.
Deterrent sprays and tape have the same limitation. They make one surface unpleasant without offering an alternative, so the behaviour usually just relocates to the next-best piece of furniture.
The only approach that reliably works is giving the cat somewhere better and making that option easy to choose.
What makes a scratching surface actually appealing
Material. Sisal rope and sisal fabric are the most widely preferred. They shred satisfyingly and give good resistance. Corrugated cardboard is the other favourite, especially for cats that scratch horizontally. Carpet is the weakest option, partly because it teaches the cat that carpet is a legitimate scratching surface, which is not the lesson you want.
Orientation. Some cats scratch vertically, some horizontally, some both. Watch what your cat currently does to the furniture. If they are working on the side of the sofa, they want vertical. If it's the rug or the arm of a chair, horizontal. Buying the wrong orientation is the single most common reason a new post gets ignored.
Height. A vertical post has to be tall enough for a full stretch with the front legs extended above the head. A post that is too short gets one confused attempt and then abandoned. Measure your cat stretched out along a wall if you want to be precise about it.
Stability. This is the one people underestimate. If a post wobbles or tips even slightly on the first use, most cats will not go back to it. A cat leaning their full weight into a scratch needs the surface to hold. A heavy base, a wall-mounted panel, or a wide footprint all solve this.
Placement decides everything
A perfect post in the wrong room is furniture. Three rules:
Put it where the problem is. If the cat is scratching the corner of the sofa, the post goes directly next to that corner. Not across the room. Right next to it. You can move it gradually later, a few centimetres at a time, once the habit transfers.
Put one near where they sleep. Cats scratch immediately on waking, as part of the stretch. A post within a couple of steps of a favourite nap spot gets used every single day without any encouragement.
Put them where people are. Because of the marking function, a post tucked away in a spare room competes badly with the sofa in the living room. If you want the post to win, it has to be in the same social space.
Making the switch
Set the new post up right beside the target furniture. Do not remove access to the old spot yet. You want the choice to be easy, not forced.
When the cat uses the post, that is the moment for a treat or attention. Immediately, not thirty seconds later. A few repetitions is usually enough.
Making the furniture temporarily less attractive helps, but only as a supporting move. Double-sided tape or a loose throw over the arm of the sofa changes the texture enough to tip the decision toward the post that is now sitting right next to it.
Give it a couple of weeks before you start moving the post to where you actually want it, and move it slowly.
More than one cat means more than one post
Scratching is territorial communication. In a multi-cat household, a single post becomes a contested resource, and the cat that loses the contest will find its own surface elsewhere. One per cat, in different rooms, is the safe baseline.
When it changes suddenly
A cat that has been fine for years and suddenly starts scratching heavily in new places is telling you something has changed. A new pet, a house move, a new person, building work next door. Increased marking is a normal response to feeling less secure about territory.
If the change is sudden and comes with other differences in behaviour, eating, or litter box use, that is worth a conversation with your vet rather than a new post.