Is it possible you have racoons in your attic? I know a guy who is in animal removal who once told me sometime they urinate in the attic so much people think they have a roof leak.

My husband went up into the attic and didn't see anything in the area above the house. Although we have considered a couple of fox squirrels that run around out in front of the house...we just haven't seen any evidence of a nest or anything. It is so frustrating because at times, unless we keep our son's bedroom door shut (it is right at the top of the stairs) the smell wafts downstairs...it is gross.

Thanks for your input though - I REALLY appreciate any and all help!

We have the EXACT same problem!
We've contacted pest control people because we thought we had rats. We've had contracters and plumbers here, but no one can find the problem! We've had it for over a year.
Please let us know if you've solved the problem!

Thanks k2 for your response. It was helpful to read the posts you mentioned. I posted a more detailed account of our problem.
I emailed the originator of this post, as her problem she described sounds most like ours, but I have not heard from her.
If our problem is pest-related, how come we can't see where they are coming in? Or hear them? Or see evidence? Unless it is in the vent?
I'm thinking we'll just get the heating vents cleaned out anyway, just to see if that helps before we tear into walls.
Thanks again for checking in on this post!

have you recently did any additions to this room Iwould take a sample of the insualtion in the attic, also, I would suggest that you check the drain pan on the a/c system to see if may be stopped and staginated water accumalated.have you checked your sons closet for possible spray cans of either,starting fluids or cleaning fluids of any type. Have you recently installed a new carpet araea near the return vent area using chipcore board as an underlay or any new plywoods which contain formalhyde glues. also, check the vent on the furnace and make sure free and not stopped up; also, does this room have flexible ductwork or does your complete house haave same. some old types of refrigeraton systems contain ammonia and could have a possible leak. are you positive it is not sewer gas. is your water heater gas, and if so,are you sure your dont have a vent stopped or came loose. have you installed a new roof over this area using underlays with formahided glues.

i have the same problem in my sons room. the attic door is in his room and there is an animal up there because i can here him moving around :( the smell of ammonia is so strong its hard to breathe at times. It started today. Yesterday it was fine, and its already horrible. we keep the door closed and you cant smell it anywhere except in that room. Its definately bigger than a mouse, does it sound like a racoon with that much pee smell that fast?

Hi
We just moved into a house and are experiencing the same smell on the top floor only. It was only in the master Bathroom but now it is all over sometimes. it disappears for a week and then come back for 1 or 2 days.
the smell is so strong that we cannot sleep well.

I sprayed Arm and Hammer Stain & odor Eliminator in the AC intakes and it seemed it improved the situation all over but now in the Master Bathroom the smell is strong only.
I have request pest control to come in tomorrow to check all including the attic.
If anybody has new ideas let us know please.

With a simular problem I had I took off a vent cover and found a very
old deoderizer in there when I removed it the smell also left

We have the same problem going on. We had a new furnace installed this summer and it seems to prevail only since I turned the heat on this fall...what's odd is that it's only one room in the house.

Same problem with our house. We had new furnace installed also this past summer and now terrible smell in one the bedrooms upstairs and now it's almost in every room of the 2 nd floor coming from the vent.

Bed bugs can leave a musty odor

Fee are experiencing the same thing. It started three days ago. At first I thought my dog had an accident so I scrubbed the floors and steam cleaned the area rugs. It has happened again the last two nights.
The smell is just in our kitchen and dining room area and comes at night then disappears throughout the day.
I have no idea where to look or what it could be.

We are experiencing the same thing. It started three days ago. At first I thought my dog had an accident so I scrubbed the floors and steam cleaned the area rugs. It has happened again the last two nights.
The smell is just in our kitchen and dining room area and comes at night then disappears throughout the day.
I have no idea where to look or what it could be.

I knew I wasn't going crazy!! I have a smell that I thought may have been a decomposing animal in my attic closet. The smell was so horrible, but we waited over 6 weeks for the decomposition to be over... the smell went away then came back! it was on and off for months when I finally smelled it really strong one morning and called our landlord. He was there within an hour and wouldn't you know... there was no smell at al while he was therel.... it came back 2 days later, but I didn't tell the landlord for risking sounding crazy.call Holanda Since it is summertime now, windows are always open, so its hard to tell if its still there.
Has anyone who experienced this ever gotten an explanation?

Have same problem, Just wondering if it could be due to fungus or mould ... but I'm in Malaysia, damp n humid here ...

Hello. Has anyone on this blog been able to solve their problems? I am now just dealing with similar problems. And I’m about to loss it. No one can give us any answers. Any answers would be greatly appreciated!!!

Yep. That mildewy urine odor appears on my porch coming from outside, from late evening until the break of dawn. It's just nauseating. There is no crawlsspace on my porch. It is flat cement slab.
I shut my porch door at night, because if I don't, half of my home reeks of it.
I have seen some raccoons in the area, but I do not think they have a nest near my home, and do not here activity inside.
I guess no one can answer what the heck it is from the looks of things.
I am guessing fungus, or a bum is pissing on the trees every evening.

Has anyone ever come to any conclusions on this smell issue? We are having the SAME problem & can not find the source! Its frustrating & nauseating! Ughhh!!!

I also have the horrible cat urine smell. Just moved into house and it was here from the first day. Asked previous owner if they kept a cat in that room - no animals ever. On cool days no smell but when the attic gets hot the one bedroom has the smell. Sniffed the walls, the floor, outlets, ac vents, no moldy window sills and it's mostly in the doorway. Nights when the attic cools down, the smell is mostly gone. Could it be mold on attic insulation from a leak in the roof?

I live in AZ and noticed in summer time the ammonia smell, especially when temp raise up to the 113. I think it comes from plastic materials in my bedroom ( a vynil massage table, plastic window decoration, a vynil decoration wall sheet) in winter time smell disappeares.

I experienced the same horrible strong urine smell in my spare bedroom about a year ago, it lasted just over two weeks then disappeared... Last night that smell came back in the same room. I steam cleaned my carpets hoping it was my dog that had an accident- but no, the smell is steadily getting stronger. Just strange that it happened about the same time last year. Any ideas? Suggestions?

We have the exact same problem!! We thought our dog had an accident, but she didn’t. It’s in about 4 rooms in our house and we’ve cleaned the AC pan, have hardware floods, and our heat pump was replaced last year. We don’t know what’s going on, but if you all find out then please let me know!!

I have the same problem in my house in New South Wales. One bedroom only has the smell. I can't find the source. It is hardly noticeable in winter but on hot days it is bad. I installed a solatube in that room to provide more light. I am wondering if it is the material of the solatube that is causing the problem. I hadn't noticed it before that.

Same problem. Strong urine smell. I just renovated my house. New roof, new walls. New concrete fiber board siding. New hardwood floors and carpet. I cant find the source of the smell.

I faced the Same problem at my house. This article helped me to get rid of the lingering odor. This is the link http://brightstuffs.com/diy-ideas-to-deodorize-home/ which you can also check out if you also are facing the same issue.

I’m having an issue too. Feel like I’m going crazy. Scrubbed carpet on hands and knees with deodorizer and nutrilizer and still it persists. My son can’t smell it but it burns my nose, makes me cough etc.... wth am I supposed to do?

We have the same problem that started a couple nights ago. Its in my daughter's room. There is no carpet, her floor is laminate. We checked everywhere in the room and nothing. My husband checked the attic and there is nothing up there and it doesn't smell up there. My daughter's room smells like something is rotting. It seems to come and go and in some areas it seems stronger, but the smell appears in different areas of the room. This is so bizarre and I feel like I'm going crazy!
Are we supposed to contact an exterminator??!!

After reading everybody's comments in this blog, I feel so much relief, I thought I was the only person in the world who was dealing with this mysterious odor. After much research crawling under the house and looking at the centralized area below the room that had the foul odor, we have found out that insulation is an animal attractant especially in extreme climate, whether it be hot or cold. So most likely what all of us are suffering from is in fact animals. For the longest time we saw no evidence of any kind of Critters. And then we began to hear the sound of a rather large animal scratching, and squeaking or whimpering. What was discovered was the animal was between the insulation and the bottom of the house. It was not in our ductwork as we originally thought. But after harboring for such a long time and having babies or inviting other family members in it's cozy little Hideaway, the smell of feces and urine and ammonia begins to permeate your subfloor and seep into your house. Once the animal feces covers a large portion of your insulation it compounds the problem . Cellulose insulation is paper based, but it is also treated with chemicals (borates) that suppress mold growth. Fiberglass does not support mold growth, but it gets dirty, and the dirt grows mold, and it is often paper faced and this paper grows mold. So this being said, can the chemicals in our insulation mixed with pet urine create an even stronger ammonia smell and grow mold? The answer is yes!
So what is the solution? We are still dealing with this, we have found the culprit and now we have to come up with an answer. Our thoughts are to get industrial strength aerosol bombs and place under the house between the insulation and subfloor. We have the ability to do that, not all houses will. Homes that cannot, perhaps just put the bombs under the house. But just as the pest smells permeated the house, I can only imagine the smell of the bomb will too. Then health issues are always a concern with smelling either. However, we are willing to try this & hopefully run this creature out and then begin the deodorizing process. It will be necessary to run an air filter in the house for several days possibly even weeks until we feel the air in the house is once again pure.
Best of luck to everyone out there getting rid of their pest problem. We have been dealing with this for almost a year and it is getting worse as the feces continue to grow bigger from more pest coming in to join its family member. But we say good riddance to them all. I hope this helps.

We have this same problem in our house, and did so when we even lived in a hotel for a while. Not sure if this helps, but I'm almost positive our neighbor in both different situations was cooking or smoking crystal meth. I have two small children and we had to isolate them in there rooms. If anyone thinks this could be it, or have similar experiences please let me know.

Call ghost busters.

Yeah, this is the site I came to when I was searching for an answer on the ammonia smell, I ripped the carpet up and tiled the floor, because I was sure it was the carpet but still had the smell, I cut the section of drywall in the area where the I thought the smell was coming from and I noticed that while I was cutting the drywall I could smell the ammonia from the drywall, so I removed the whole section of wall only to find there was mice living and urinating in the ceiling!

we have resently had our central air system replaced and we’ve also been having an awful urine smell ever since. it’s coming from our bathroom and we thought it was our septic. It’s hard to tell whether it’s coming from the attic or crawl space. First thought is the contractors did something and caused it but then how would I prove such a thing.
I really need your input if you have found the problem. Thanks in advance.

i live in apartment, last saturday my shower in my master bath flooded , they finally came to fix it, they couldn't they had to come back the next day. well they didn't get the water out of the carpet. i steamed clean my carpet 2 , the smell is really bad. i can't figure it out, when maintance comes to fix the problem they said it was someone putting drano or something down the drain. that didn't happen, maintance also checked the apartment above me and next to me. nothing, they said to call back to if the smell was still there. it's so strong , and i have heart issues, so this is not good for me to be in . I've read where they said that there is a p-trap on the sewer pipes, they won't check it out, supposely it's on the roof? i've burned candles, air fresheners, i'm at a total loss on how to get this smell out. i need all the help i can get