A wall-to-wall carpeted floor has four layers, and a pet accident can reach all of them. Most people only ever clean the top one.
That gap explains almost every "we cleaned it and it still smells" call we get. The carpet looks fine. The problem is an inch below it.
Where the urine actually goes
Top to bottom, the layers are:
- The carpet fibers, the part you see and vacuum
- The backing, a woven layer that holds the fibers in place
- The pad, usually foam or bonded scrap foam, there for cushion
- The subfloor, which in most Katy homes is a concrete slab
Urine lands on the fibers, and if nobody blots it fast, gravity takes it through the backing within minutes. Once it hits the pad, it spreads sideways, which surprises most people. Foam is full of tiny air pockets that wick liquid outward, so a puddle the size of a saucer on top can turn into a contaminated patch the size of a dinner plate underneath.
That's also why spraying the visible spot rarely works. You're treating the saucer. The plate is still there.
Why the pad holds on to it
Pad is basically a sponge that nobody ever wrings out. It holds moisture far longer than the carpet above it, so the surface can feel completely dry while the pad is still damp.
In that damp, dark layer, bacteria break down the urine and keep producing that ammonia smell for weeks or months. Dried urine salts left behind pull water back out of the air, so the smell comes and goes with the weather, and in a Gulf Coast summer the weather is mostly humid. Your pet can also smell what you can't, which is why dogs and cats keep going back to the same spot. The pad is advertising it.
Over time the acids in old urine weaken the backing, and in bad cases the moisture reaches the slab, where it can sit and leave a stain on the concrete itself. Rental carpet machines tend to make all of this worse. They put down a lot of water and don't have the suction to pull it back out, so they rinse the urine further into the pad and then leave it wet.
Signs it has reached the pad
You won't see the pad without pulling the carpet up, but it usually gives itself away:
- The smell returns a few days after every cleaning
- A spot you cleaned shows up again as the carpet dries (that's wicking, contamination climbing back up the fibers)
- Your pet sniffs, circles, or reuses the same area
- A faint discolored patch slowly gets larger
- The odor gets stronger on rainy or muggy days
One of these by itself might be nothing. Two or more, and the pad is very likely involved.
What it takes to fix
Fresh accidents
If the accident is fresh, blot hard, dilute lightly with cool water, and dry it with a fan. Our guide to handling a fresh accident covers that routine step by step, along with the things not to put on it.
Pad that has been soaked for a while
Once urine is in the pad, it needs a treatment that goes where the urine went. Ours is a live enzyme treatment applied in enough volume to reach the pad, then given time to break down the residue there before the carpet is cleaned and dried. It's a very different job from a surface clean, and it's the reason a pet spot can be fixed without tearing anything out. Here is how our pet treatment service works if you want the details.
Here's the honest part. When a pet has used the same corner for a year, the pad there can be too far gone for any treatment, and the right answer is cutting out that section of pad and replacing it. That's not a job we pretend to fix with chemistry. Your technician will tell you plainly if that's where you are, before you pay for anything.
Most spots aren't that bad, though. If yours keeps coming back, call 281-789-8998 and we'll come look at it. Pet treatment is $25 off with our current coupon, and we cover Katy plus Brookshire and the I-10 corridor west of town.