Key Takeaways
- Small isolated spots: Repairable with padding replacement and enzyme treatment—$150–$300
- Multiple spots or large areas: Usually requires replacement—$800–$2,000 per room
- Odor removal limits: Enzymes work on fresh urine; old urine soaked into subfloor is permanent
- Padding replacement: Essential for any urine repair—$1–$2 per square foot
- Subfloor sealing: Required if urine reached wood or concrete—$50–$150
- When repair works: Fresh damage, small area, padding is the deepest penetration
- When replacement needed: Old stains, multiple accidents, subfloor saturation, visible carpet damage
How Pet Urine Actually Damages Carpet
Urine soaks through the carpet into the padding within seconds. The padding absorbs it like a sponge. From there, it spreads outward—sometimes six inches or more beyond the visible stain.
The carpet fibers show the stain, but the padding holds the smell. This is why scrubbing the carpet surface doesn’t eliminate odor. The source is underneath.
If the urine sits for more than a few hours, it soaks through the padding to the subfloor. Wood subfloors absorb urine. Concrete subfloors don’t absorb it, but the urine pools on the surface and crystallizes.
Uric acid crystals form as the urine dries. These crystals reactivate when they get wet—humidity, spills, cleaning. This is why old pet stains smell worse on humid days.
Repeated accidents in the same spot saturate the subfloor. Wood subfloors can rot. Concrete subfloors develop a permanent smell.
The carpet backing can delaminate—the backing separates from the pile. Once this happens, the carpet won’t hold tacks or seams. Repair is pointless.
For general carpet damage, see our guide to carpet repair options.
When Urine Damage Can Be Repaired
Small, fresh accidents—less than a week old—can often be repaired. If the urine only reached the padding, you can replace the padding and treat the subfloor.
The process: the installer pulls back the carpet, cuts out the soaked padding, treats the subfloor with an enzyme cleaner or primer, installs new padding, and re-stretches the carpet.
This works if the carpet fibers aren’t visibly stained or damaged. If the stain is light and the smell is recent, repair is worth trying.
Isolated accidents—one spot in a bedroom, one spot in the hallway—can be repaired. Multiple spots in one room make repair impractical. You’ll spend $500 repairing four spots when replacement costs $1,200.
If the accident happened on carpet over concrete, repair is easier. Concrete doesn’t absorb urine the way wood does. A thorough cleaning and enzyme treatment usually eliminate the smell.
If the accident happened on carpet over wood and you caught it within 24 hours, repair is possible. Beyond that, the wood has absorbed the urine. Sealing the wood with a shellac-based primer traps the smell, but it doesn’t eliminate it.
When Replacement Is the Only Option
Old stains—months or years old—rarely repair successfully. The urine has crystallized in the padding and subfloor. Enzymes can’t break down old crystals reliably.
Visible carpet damage—bleached fibers, backing separation, holes from chewing—can’t be repaired. You can replace the padding and treat the subfloor, but the carpet still looks ruined.
Multiple accidents in one room mean the entire room needs replacement. You can’t patch eight spots and expect the carpet to look or smell acceptable.
If the subfloor is rotted, replacement includes subfloor repair. Rotted wood has to be cut out and replaced before new carpet goes down. This adds $500 to $1,500 to the job depending on the extent of damage.
If the smell has spread to baseboards or walls, the problem is bigger than the carpet. Baseboards may need replacing. Drywall may need sealing or replacing. At that point, you’re looking at a full room renovation, not just carpet replacement.
For full room replacement costs, check our carpet replacement guide.
Enzyme Treatments and Their Limits
Enzyme cleaners break down uric acid crystals. They work by digesting organic material—urine, feces, vomit. This eliminates the source of the smell instead of masking it.
Enzymes only work on material they can reach. If the urine is in the padding, spraying the carpet surface does nothing. The enzyme has to contact the padding directly.
Enzymes need time. You spray the area, let it sit for 10 to 15 minutes, then blot it. Some products require overnight contact for deep stains.
Enzymes don’t work on old, crystallized urine as well as fresh urine. The crystals resist breakdown. Multiple treatments may be needed.
Enzymes work best on padding and carpet backing. They work poorly on wood subfloors because wood absorbs the urine deep into the grain. Once it’s in the wood, enzymes can’t reach it.
For wood subfloors, sealing with a shellac-based primer—like BIN or Kilz—traps the odor. The primer creates a barrier so the smell doesn’t rise through new carpet. This isn’t a perfect solution, but it’s the best option short of replacing the subfloor.
Padding Replacement Process
The installer pulls back the carpet from the tack strips in the affected area. For a small spot, they only pull back a section. For widespread damage, they pull back the entire room.
They cut out the soaked padding with a utility knife. Padding is cheap—$1 to $2 per square foot—so they remove a generous area around the stain. Urine spreads farther than you think.
They inspect the subfloor. If it’s wood, they look for discoloration, softness, or rot. If it’s concrete, they check for pooled urine or staining.
They clean the subfloor with an enzyme cleaner. For wood, they may also apply a shellac-based primer to seal the odor. For concrete, enzyme cleaner is usually enough.
They cut new padding to fit the removed section. The new padding should match the existing padding thickness. Mismatched padding creates lumps and uneven wear.
They tape the padding seams to prevent shifting. Then they pull the carpet back over the new padding and re-stretch it to the tack strips.
If the carpet was badly soaked, the backing may have water stains or weak spots. The installer checks this before re-stretching. Weak backing won’t hold tacks.
Subfloor Issues and Odor Persistence
Wood subfloors are the worst for odor retention. Plywood and OSB absorb urine deeply. If the wood is saturated, no amount of cleaning eliminates the smell entirely.
The best approach: clean the wood with an enzyme cleaner, let it dry completely, then seal it with a shellac-based primer. The primer traps the odor molecules in the wood. New padding and carpet go over the sealed wood.
This works for mild to moderate urine damage. For severe saturation, the wood may need replacement. You’ll see dark stains that go deep into the grain. This wood is compromised and should be cut out.
Concrete subfloors don’t absorb urine, but the surface can hold odor. Enzyme cleaners work well on concrete. Let the cleaner sit for 15 to 30 minutes, then scrub and rinse.
For stubborn concrete odors, use an acid wash—muriatic acid diluted with water. This etches the surface and removes the top layer where the urine sits. Rinse thoroughly before laying new padding.
Radiant heating under the carpet complicates things. Heat reactivates uric acid crystals. You’ll smell the urine every time the heat kicks on. In these cases, odor-blocking primers are essential.
Deodorizing vs Actual Odor Removal
Deodorizers mask the smell. They don’t remove the source. Spraying Febreze on a urine stain makes it smell like flowers for a day, then the urine smell returns.
Odor removal requires eliminating the uric acid crystals. Enzymes do this. So does replacing the padding and sealing the subfloor.
Charcoal bags, baking soda, and air fresheners are useless for pet urine. They don’t interact with uric acid. They just add competing smells.
Ozone generators can break down odor molecules, but they don’t work on urine soaked into padding or subfloors. The ozone can’t penetrate deep enough.
Steam cleaning pushes urine deeper into the padding and subfloor. It makes the problem worse. Never steam clean pet urine stains.
If you’ve tried multiple deodorizers and the smell persists, the urine is in the padding or subfloor. Surface treatments won’t help. You need padding replacement and subfloor sealing.
Preventing Future Urine Damage
Train pets to use designated areas. Cats need clean litter boxes. Dogs need regular outdoor breaks.
Clean accidents immediately. Blot—don’t rub—with paper towels. Soak up as much urine as possible before it reaches the padding.
Use an enzyme cleaner designed for pet urine. Apply it generously to the affected area and let it sit for the recommended time.
For repeat offenders, restrict access to carpeted areas. Gate off bedrooms or hallways. Use washable rugs in areas the pet frequents.
Consider hard flooring in high-risk areas. Tile, vinyl, or laminate in the kitchen, entryway, and bathroom prevent urine from soaking into padding.
If the pet has a medical issue—incontinence, urinary tract infection—address it with a vet. Chronic accidents destroy carpet no matter how fast you clean.
For basements, use carpet tiles instead of wall-to-wall carpet. If a tile gets soaked, you replace one tile instead of the entire room. Learn more about basement carpet options.
FAQ
Can pet urine damage in carpet be repaired? Sometimes. Small, fresh accidents can be repaired with padding replacement and enzyme treatment. Old stains, multiple accidents, or subfloor saturation usually require carpet replacement.
How much does it cost to repair pet urine damage in carpet? $150 to $300 for small isolated spots including padding replacement and subfloor treatment. Full room replacement costs $800 to $2,000.
Will enzyme cleaners remove old pet urine smell? They work better on fresh urine. Old urine crystallizes and resists enzyme breakdown. Multiple treatments may help, but old stains often require padding and subfloor replacement.
How do you get rid of pet urine smell in carpet permanently? Replace the soaked padding, clean and seal the subfloor with enzyme cleaner and primer, then re-stretch the carpet. If the carpet backing is damaged, replace the carpet.
Can you patch carpet damaged by pet urine? Yes, if the damage is small and isolated. The installer cuts out the damaged section and seams in a donor piece from a closet. This costs $100 to $250 depending on size.
Does steam cleaning remove pet urine from carpet? No. Steam cleaning pushes urine deeper into the padding and subfloor. It makes the smell worse. Use enzyme cleaners instead.
How far does pet urine spread in carpet padding? Six inches or more beyond the visible stain. Urine spreads outward in the padding, so the affected area is always larger than it looks.
What is the best enzyme cleaner for pet urine? Products with live bacteria cultures work best—Nature’s Miracle, Rocco & Roxie, or Simple Solution. Apply generously and let it sit for the recommended time.
Can you seal pet urine smell in the subfloor? Yes. Shellac-based primers like BIN or Kilz trap odor molecules in wood subfloors. This doesn’t remove the odor, but it prevents it from rising through new carpet.
When should you replace carpet instead of repairing pet urine damage? When the damage is widespread, old, or involves multiple accidents. Also replace if the subfloor is rotted, the carpet backing is delaminated, or the smell persists after padding replacement.