Why Does My Attic Smell Like Urine?

Why does my attic smell like urine?

why does my attic smell like urine

There are plenty of things that could cause your attic to smell like urine. The first reason that comes to mind is a rodent infestation or perhaps some other animal infestation. Before you call pest control, it’s a good idea to check the attic and look for any signs of animal infestation, water leaks or dampness, or unusual things that stand out.

Common attic odors

common attic odors

Besides a rat infestation or other animal invasion, there’s a good chance the urine smell from your attic could be due to a mold problem or even a decomposing animal.


If you pop up to your attic and you’re instantly assaulted by a heavy musty smell, that could be due to mold. You’ll usually smell the mold before you see it, but in extreme cases, you’ll be able to see the mold on the walls or ceiling.

Attic mold is often white, gray, or black. White attic mold is typically fuzzy and furry in appearance. Typically, the cause of mold in your attic is leaks in the roof.

One sign that your attic may have mold growth before you even see or smell it is that you and your family have been experiencing respiratory issues. If you find that you have been having trouble breathing or you’ve been coughing a lot it’s a clue that you may have mold somewhere in your home.

If you have mold elsewhere in your home, it most likely originated from mold spores in your attic which can affect the air quality of your home if it hasn’t already, potentially making you sick.. It’s best to have your attic cleaned yearly to avoid mold growth and mold smell as well as treat water leaks and make sure you’ve got good ventilation up there.

Rodent droppings/rat urine

How can you tell that your attic has rodent urine in it? Rat urine, like most animal urine, has large amounts of nitrogen inside it that breaks down quickly and produces ammonia. Ammonia is that strong, sickly sweet urine smell you’re probably already familiar with.

You can tell that the foul odor you’re smelling is rat urine because it smells powerful, musty, and sharp. You probably won’t be able to see the urine itself which is why it’s best to check for rodent droppings to know what you’re dealing with.

Checking for rodent droppings

Before checking the attic, if you suspect a rodent infestation or you smell rodent urine you need to wear a face mask and gloves. Rodent droppings can transmit diseases like hantavirus or leptospirosis.

Fresh droppings are brown and they look soft and moist. Old droppings are dried out and typically gray. If you see a mixture of these droppings, you’ve had a rat infestation for quite some time.

You may have other rodents living in your attic (for example, squirrels). Squirrel feces are typically clumped together rather than in single specks like rat feces. You probably won’t see any urine stains from squirrels either; unless you use a black light, the smell of rodent urine and the discovery of feces will be your only clues.

Dead animal smell

This is potentially one of the worst smells you can encounter in your attic. Rat, rodent, and other pest infestations like birds not only mean that the animals are living in your attic — but they’re also dying there.

The smell of decomposing flesh is a stench unlike any other, especially in the summertime. It’s a smell you can taste even if you try not to breathe.

A dead animal in your attic doesn’t pose as serious a risk to your health as rodent urine or feces, but if your pet comes into contact with the dead animal it can make them sick. And be honest — do you want to be the one to dig around in your attic and remove a decomposing carcass?

How can you recognize the smell in your attic as a dead animal carcass? The smell may take up to a week to be noticeable in your house if the animal (or animals) died in the attic. It’ll be one of the worst smells you can ever remember crossing your nostrils. It isn’t musty like urine or mildewy like mold; it’s more offensive, more visceral, and more intense.

Unfortunately, if this is what’s making your attic stink, you have to wait it out. There’s nothing you can do to make the smell go away, no quick fix. Sanitize, then wait. You may be able to get a pest control professional to help, however.

Can a gas leak smell like cat urine?

can a gas leak smell like cat urine

No, a natural gas leak doesn’t smell like cat urine. In fact, natural gas alone is odorless. An additive gives it a somewhat pungent scent that’s more like sulfur in some ways so people can detect a gas leak by the scent.

Freon odors

There is another possibility, however: Freon refrigerant. Many people have reported that the gas Freon smells like cat pee to them among other things like paint stripper, nail polish remover, or classic ammonia.

The variation in smells depends on the person and the chemical makeup of the Freon gas and what was mixed with it as Freon is often mixed with a lubricant and also a leak detection chemical in some cases.

Freon can leak from heat pumps and air conditioners so if you do smell something resembling cat urine in your attic or anywhere in your house, it’s best to call an HVAC specialist to check for leaks in your duct system.

Mold scent

Toxic black mold in a damp, musty area can also smell like cat urine so make sure to cover all potentialities. Dampness and high humidity encourage the growth of mildew or mold which has a tendency to have a musky, funky scent that may seem like a cat urine smell to some.

Why does my house smell bad after a vacation?

why does my house smell bad after a vacation

If you’re only gone for a weekend the chances are your house will smell a bit closed up but it won’t smell bad. However, if you’re gone for a few weeks or a month or so you may wonder why on earth your entire house smells weird after you come back.

  • If your house smells musty and stale the main reason is due to lack of air circulation. It shouldn’t be a terrible smell, but it’s not pleasant. Don’t worry if your home has a musty odor when you get back after an absence; it should disappear within a few hours or a day. If the smell is more than just a musty, stale absence of fresh air, you may have another problem.
  • Because of the lack of airflow during your absence, moisture-rich environments like bathrooms, laundry rooms, or kitchens could potentially grow mold during a long absence so the musty odor you’re smelling could be mold.
  • Old foods or garbage that weren’t disposed of are sources of odors over time.

To see whether it’s a mold issue, a gas leak, or just normal staleness from lack of airflow, you can turn the air conditioning up, open doors and windows, and see whether anything changes or goes away the first few hours you’re back home.

A gas leak is a potentially hazardous problem so you may want to check on that first before airing out the house.

James Marshall

About the author

James is a business management professional and consultant with a former background in maintenance, repair, and hands-on projects. He enjoys DIY tasks and maintenance around the home as well as part-time writing. Read more »