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Cat pee and dog toenails: Are pets always a deal-breaker for hardwood floors?

There are only two things that can ruin a hardwood floor beyond all hope: floods and urine.

pet stain for webFloods are fairly rare, but almost everybody has dog or a cat or a rabbit that will eventually leave a puddle on the hardwood floor.

If you catch the puddle and wipe it up while it’s still fresh the problem is minimal; modern polyurethanes are designed to resist accidents like this. 

But as urine sits and decomposes, it becomes more alkaline and more corrosive and eventually you have the equivalent of undiluted ammonia burning through your finish and into your wood. This tends to happen when there is carpet or a rug over the hardwood floors because it keeps the liquid from drying and allows it to sit in contact with the floor below as it breaks down.

The problem is compounded by the fact that pets, once they've marked a spot, continue to use it which practically guarantees that there will always be fresh ammonia forming at that site. Unfortunately, neither the wood finish nor the finish itself can resist this onslaught. 


For some reason, there is a persistent belief that stains like these can be removed easily by sanding or bleach.

Unfortunately, this simply isn’t true.

The vast majority of pet stains have to be patched out; that is, the damaged wood must be removed and replaced with new wood.

By the time a pet stain is as dark or extensive as the ones shown here, the ammonia burn has penetrated deeply into the hardwood, probably far deeper than you would want to sand. So don't waste your money on anything "guaranteed" to remove pet damage.  

Try sanding

You can at least try to sand the damage out, just to make absolutely sure you don't have to tear the boards out - use an agressive sander at least 36grit so you can grind through the damaged wood fiber. Keep the sander moving; you don't want to leave sander-shaped depressions in the wood!

The smell is llikely to be bad as you sand, but if you see the stain lighten, there might be hope! The photo at right is a cat accident that will probably sand out, or at the very least lighten considerably after sanding.  

If you discover a pet stain on a finished hardwood floor and you suspect it's been there for more than 4 hours, douse the spot with a mild acid like vinegar, which will at the very least neutralize any ammonia (which is an alkali) that may have formed and will arrest its corrosive ability. Let the stained area dry completely, which could take two weeks, before you attempt any corrective measures.

Pet toenail-scratches...

Dogscratches webare very unlikely to cause permanent damage to a hardwood floor.

Even when the damage goes through the finish and into the wood, it can usually be sanded out. But the bad news is that they have to be sanded out, which costs money or time.

So, your first job as an owner of a heavy animal with claws is to understand that your wood floor needs more protective coating or more frequent maintenance (or both) if you want to keep the appearance of scratches to a minimum.

Even the hardest finishes can eventually be worn or scratched off and your energetic mastiff can do that just as well as a sander can.

Here's how you can avoid having to resand your floors constantly:

Use more coats of finish. If you have enough finish on the floor, the scratches will be in the plastic of the finish, not the wood. Finish scratches can be easily fixed with a fresh topcoat of more polyurethane.

Scratches in the wood have to be sanded out and, since polyurethane floors can be easily spot-sanded, you'll have to sand the entire room. And if that room runs into other rooms, you'll find it hard to find an unobtrusive place to stop the sanding madness. Better to simply prevent the sanding madness with more polyurethane.  

Use a tougher finish. There are a few brands of waterborne finish (Traffic is the product that we carry) that are catalyzed with cross-linkers that do provide a better bonded, tougher finish that is harder to scratch and harder to wear through. It tends to be more expensive, but it is still a fraction of the cost of resanding a floor.

You can recoat an existing finish, even if you're not sure if it was initially an oil-based or a waterbased polyurethane, with one of these commercial, catalyzed finishes. And you can do it yourself if you read this. Do it sooner rather than later.

What if I don't like that extra-plastic look of many coats of polyurethane? You can absolutely use a penetrating oil (like Rubio Monocoat) for a more natural, low sheen look but pets will increase the frequency of your maintenance. Those penetrating finishes allow the wood grain itself to take the brunt of the wear and friction of living. Dogs and cats increase that friction, so you'll perform your touch-ups at least quarterly.

The advantage of the penetrating finishes is that the maintenance can be done selectively, exactly where the damage has occurred - you don't even have to move furniture if the damage doesn't extend there.

Keep your puppy's toenails clipped and wipe the sand and grit off their feet when they come in from outside.

Use rugs in the traffic lanes that your pets use most frequently or aggressively. If your dachsund herd makes a high-speed beeline for the door when the postman rings, use a runner along the path they use.   

Want to know what else causes damage to your floors? Read our blog to find out.