5 Ways to Remove Dog Urine Stains from Your Deck

So convenient, Grover scratches at the patio door, you slide it open and let him out unto the deck to do his business. Saving you slipping on your shoes and taking him out to the yard. But will he stain your deck? Will dog urine stain your deck?

Yes, dog urine can stain your deck. Composite decking will not be permanently stained by dog pee, but softwood decking like cedarOpens in a new tab. or treated pine will.  The dog urine on the wood causes a chemical reaction darkening the wood, leaving the deck with unsightly splotches.

As already noted, not all decking will be stained by dog urine. Capped composite with its protective polymer coating will not soak up the dog urine. The dog urine can be easily sprayed off or washed. Not being absorbed, it will not stain the decking.

Wood decking is a different story. Wood, by nature, is absorbent. At one time, your decking was part of tree wicking water 30 or more feet into the air. The cellar structure of wood acts like a million little sponges soaking up water, impurities and all. And there lies the problem, urine is not pure, but contains impurity.

“Urine is an aqueous solution of greater than 95% water. Other constituents include urea, chloride, sodium, potassium, creatinine and other dissolved ions, and inorganic and organic compounds.”

LumenOpens in a new tab.

It’s that other 5% that is staining your deck. If dog pee were just water, then if the sun quickly dried up the deck, we would have no problem. But it’s not, dog urine contains chemicals that react and darken the wood.

In bad cases, the urine will leave dark black marks on the decking. Black spots more likely to form on hardwood decking but can also set on other wood. This is because of tannins in the wood. Cedar and redwood are rich in tannins, which is why they are prized for decking as it makes them less susceptible to rot.  

“They (tannins) are large molecules that bind readily with proteins, cellulose, starches, and minerals.”

U.S. Forest Service 

The increased level of tannins increases staining from urine. As the large molecules bind with the compounds in the urine and turn black. Your beautiful wood deck will lose its beauty if Fido pees on it.

Worse than discoloration

Not only will dog pee stain a wood deck, but the smell emitted by urine saturated decking is worse. A dog peed stained deck will emit a pungent ammonia smell, which will destroy your enjoyment of your deck more than dark stains on the decking.

How can you relax on your deck with the smell of urine wafting over you? Smell is such a powerful sense. The fragrance of fresh bread delights us and brings a smile on our face. The smell of urine repulses us. As if it was burning our nostrils. A deck smelling like dog pee is repulsive.

This overpowering odour increasing on hot summer days. The days you want to enjoy the weather on your deck the most. Are the days it stinks the most.

The smell of dog pee is worse for a deck than discoloration.

Which decking is stained less by dog urine?

The first few milometers of your decking decide if dog urine will stain or not. If the decking soaks up the urine, it will stain your deck. If the decking repels the urine or blocks it from getting into the decking, your deck will be fine.

Cedar and treated decking will quickly soak up the pee. Entrapping it and staining the decking. Sealing your decking regularly will decrease absorption rates but not stop it. Remember, droplets of water is how you tell when your deck needs to be sealed. You can read more by clicking hereOpens in a new tab. about deck sealing.

The good news is quality composite decking is capped. The polymer cap seals and protects the decking core from staining. This means if Fido pees on your composite decking, the urine is not absorbed by the decking but remains on the surface where it can be easily washed off.

TimberTech makes composite decking that goes even further. Their Proline is capped containing Mold Guard Technology™, protecting the decking from mould and moisture. Not only is the urine not absorbed by the decking, but the cap limits mould from growing on the decking.

Just one more reason to have a composite deckOpens in a new tab..

Regardless of the decking, dog pee needs to be cleaned off. Here are a few ways to remove stains from your deck.

Cleaning dog pee off your deck

The first response is dilution. If you notice, Fido has just peed on the deck. Spray it off with a garden hose, a bucket of water or even a spray bottle. By immediately washing off the urine, it will not soak in and stain the decking. If you have a new puppy or an older dog who is having accidents more frequently, having a spray bottle handy on the deck will make this task easier. This is a good idea both for wood and synthetic decking.

For surface-level decking of dog pee stains on your deck

When you are busy with your nose in a book or stepping outside are greeted with the smell of pee on your deck. A little more cleaning is required. You have two possible options.

Using vinegar to remove surface dog pee stains from your deck

Diluted vinegar is excellent in cleaning off dog pee as it deodorizes and sanities at the same time. Eliminating the smell and contamination. You will not want to use pure vinegar but dilute it four to one with water.

Then take a stiff brush and scrub it into the decking. This is especially important with embossed composite decking as the tracking forming grooves can also trap urine. Working the solution back and forth, pulling all the urine out.

After scrubbing the decking, rinse thoroughly.

If you can still smell the pee, then reapply, let it sit on the decking for 30 minutes and rinse again.

Using Baking Soda to clean dog pee stains off your deck

With baking soda, grab your spray bottle. Wet the area and sprinkle with baking soda. Wait 30 minutes and scrub the area and rinse off.

One of the advantages of baking soda is the chemical reaction with the urine will pull some of the urine out of the wood. It’s possible to work out a pee stain on the deck, allowing the reaction to pull the urine to the surface where it can be wiped off.

Baking soda is also good in neutralizing the urine smell of the decking stain. Just like the a box of baking soda helps to remove smells from your fridge. It does the same with the deck, absorbing the smell. Making your deck better again.

Both vinegar and baking soda work well for wood and composite decking. Meaning you can clean your deck off as often as your dog has an accident.

For persistent urine stains, you will need to use something more powerful to remove the stain and smell.

Using deck bleach to remove dog pee stains

A word of caution, bleach literally bleaches the wood. Over application can result in lightening the wood. Creating the opposite effect of urine. Instead of dark spots on the deck, you will have light spots where you applied the bleach. Chlorine bleach can also break down the wood fibres damaging the decking when over-applied. Along with destroying or killing the surrounding greenery around your deck.

But if your wood deck is unusable because of the stench of dog urine and unsightly stains, bleach is your best solution. I would recommend integrating bleach cleaning with staining your deck. Power wash down the decking. Bleach the entire deck creating a clean and consistent lighten wood. Then after cleaning off the deck bleach and cleaner, let dry and seal the deck with a fresh coat of stain.

Annual bleaching your entire wood deck will not negatively impact the decking, but if you are pouring bleach on your deck every time Grover pees, it will be a problem. Use vinegar or baking soda for immediate cleaning to prevent staining. Save the bleach for cleaning off the entire deck from deeper stains. After repeated peeing on the deck.

Never use chlorine bleach on composite decking. Bleach on composite decking can cause premature chipping and cracking, damaging the structural integrity of the decking. Also, chlorine bleach can corrode metal fasteners. There are deck cleaners designed for composite decking, pay the money, buy the right cleaner. 

For really stubborn deck stains that deck whitening bleach cannot remove there are two other products available. These are powerful stain removing chemicals and should not be your first response to a deck stain. But if a stain is persistent you have options.

Removing deck stains with hydrogen peroxide

Hydrogen peroxide is a highly unstably compound of distilled water with an extra molecule of oxygen. Because of its instability, hydrogen peroxide contains stabilizers like phenol, acetanilide, sodium stannate, and tetrasodium phosphate. Food grade hydrogen peroxide is the exception, not contain any stabilizers. Take care that both you and your dog do not ingest. Its good for removing stains but not good for drinking.

“H202 destroys microorganisms 5,000 times faster than chlorine. It is effective against all of the bacteria, which chlorines can remove, and exceeds chlorine in neutralizing pathogens, viruses and cysts. Unlike chlorine, H202 is environmentally friendly because its waste by product is only oxygen and water.”

Nature SanteOpens in a new tab.

I remember as a kid my mother would use hydrogen peroxide to clean out cuts and scrapes. It would sting like a bugger but was amazing to watch the little bubbles, foaming out the cut. Removing all the impurities from my cuts. The same happens with a deck stain. The hydrogen peroxide bubbles, carrying the impurities from the stain out of the decking. Bubbling to the surface where it can be cleaned off.

To remove the stain, soak a cloth with hydrogen peroxide and dab the stain. Let it dry and watch the stain disappear. You may need to repeat a few times to fully remove the urine stain. For a darker stain, soak a towel and set it over the stain for a few hours and then remove and let dry.

Hydrogen peroxide will discolour the decking. So, it should only be used prior to re-staining the deck. As the hydrogen peroxide will not only remove the impurities of the urine but also the deck stain. The good one, the one you choose, not Grover’s accident.

Using enzymatic cleaners to remove deck stains

A word of caution, your playing with fire with enzymatic cleaners. They are effective in removing pee stains by helping bacteria to decompose the urine particles staining your deck.

“These smaller particles—organic wastes, urine, grease, stains—become “food” for bacteria to digest and break down into two basic compounds—carbon dioxide (CO2) and water (H2O).”

Nyco ProductsOpens in a new tab.

Which is good except, bacteria also cause fungi and wood rot. The very thing your wood deck is treated against and why you stain it. For the fungi doesn’t rot your deck. Again, clean your deck thoroughly after treating and re-stain to prevent the bacteria from rotting your deck.

A highly recommended enzyme stain remover for pets is Rocco & Roxie Stain and Odor Eliminator. If you are going to use enzymatic cleaner on your deck, look for it.

In conclusion, Dog urine will stain a wood deck

If your wood deck has a surface urine stain clean with baking soda or water. For more stubborn deck stains, you can bleach the wood or remove with hydrogen peroxide or an enzymatic cleaner. But whenever you use a more powerful stain remover, the decking will need to be re-stained to protect it from the elements and future urine stains.

Enjoy your deck with your dog, and if an accident happens, you know now how to clean it.

Ryan Nickel

A Red Seal carpenter, passionate about building decks to be enjoyed.

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