Today I went down into our basement and smelled an intensely ammonia-like almost urine smell. I investigated a bit and found no obvious leaks, burst pipes, etc. and am stymied. We generally have a moisture issue in the basement, which we have not addressed in the 3 years we've lived here, but this smell is entirely different, and seems to have come out of nowhere. I didn't smell it yesterday.

We do not have pets, but we do have an infant, and we are using "gDiapers," which are flushable and have not given us any plumbing problems in the 4 months we've been using them. We live in a 100 year old rowhome and by the thickness of the dust and detritus that has accumulated on the plumbing (big, 8-inch or so diameter pipe - is this the sewer pipe?) in our unfinished, concrete floor basement, I'm guessing the plumbing is pretty old. Any ideas? This is obviously quite disgusting... thanks in advance!

Have you checked the floor drain if you have one? Regards, Tom

I am not sure if I have one - how would I know? We've got lots of stuff stored down there; it's only about 1100 sq feet but there's a lot to move around.

Look for the floor to slope to a floor drain. Regards, Tom

It doesn't look like we have a drain; any other ideas? My mom said it could be gas, but I have never known gas to smell like ammonia.

I had the same problem, I just took everything out of the basement and sprayed everything with scrubbing bubbles, then fbreeze. It smelled nice, but I could still slightly smell it. I put a dehydrater in the basement and its still there, it still very moist. I'm going to put 3 more in there to see if that solves the problem

Do you have any fixtures in your basement" A toilet or sink? Is the sewer main line below the cement floor or is it above the floor line? Tom

No fixtures at all; The sewer line I believe runs down the wall and then under the floor.

If you have no fixtures or a floor drain in the basement I fail to see where the odor could be coming from. Feel around the drainage pipes. Any moisture there? Do you have a dog or a cat? Regards, Tom

I had that problem once... then I found out why my cat didn't seem to need her litter box anymore...

We don't have any pets and the basement is closed so our neighbors' cats could not have access, as far as we know. There must be moisture someplace down there; thanks to all for responses and suggestions!

I also live in a really old home. My basement walls smell intense ammonia too, I believe it is the white paint that they put on the stone wall, interior. It is just a guess.

Knucklez

It bothers me that everyone writes this off to be cat pee or dead rats. I too have this problem and I've done it all. The smell is still there wofting up the basement stairs and my cold air returns. I'm sorry I don't have an answer for you, but know you're not alone!

I just read something on the web that said it's from mildew, not mold.