Basement Odor

My mother’s house has had an odor in the basement for the last 2 summers.  It is NOT sewer gas – which is everyone’s first suggestion.  It smells like cat urine, but there is no cat.  The odor is not there in the winter – whether the smell is gone or the furnace removes it, I can’t say.  The smell is worse during/after a rain.  We have had the plumber, who cleaned out the sewer pipes, etc, and found nothing else wrong.  I had the borough engineer out, who was unable to offer any ideas.  It seems to come from one corner of the basement floor, and sometimes the bare concrete is dark, as if water is leeching up from the ground.  There is never a puddle.  We have already tried the enzyme odor removers – to no avail. We are having the tile floor removed and will have the concrete painted with an epoxy paint, but don’t want to do the work if the smell will still be able to get through the paint.  Anyone have any ideas?  Thanks!

The Money Pit Answer

It is rare but sometimes fiberglass insulation develops a urine-like odor from amines that are used in the adhesive manufacture. Moisture exacerbates the emission.

Pull some of the fiberglass out and put it in vegetable steamer and see if it smells after you heat it up in a humid, hot environment.

Don't spend any more money on "remediation" until you are sure of the problem.

And let us know if it's the fiberglass.

Jeffrey May

May Indoor Air Investigations

Author: Jeff May's Healthy Home Tips

3 Answers
sueb409 answered 5 years ago

My brother bought a farm, and you could still smell the cows in the barn on a humid day years after the last cow was there.  There may have been a cat in the basement once upon a time.


My husband and I were moving to a new apartment, but the main bedroom was full of dog urine from the previous occupant's dog.  After trying many things to get the smell out, I finally tried vinegar.  I put newspapers on the floor, poured a gallon of vinegar on them, and left.  The next day the vinegar had dried, leaving the newspapers looking like a dog had peed all over them.  Later we found one spot that needed to be done again, but it worked really well.  The floor was wood, but if the urine soaked in whatever your flooring is, it might just come back out.


Good luck!



Sunzyme answered 5 years ago

Sounds like cat urine to me! "the odors are not there in the winter" " the smell is worse during after rain".  Humidity  and heat cause the salts in urine to release thus creating the malodor. I would recommed a enzyme concentrate like   

Note: the enzyme must make contact with the odor causing urine. Concrete can soak up urine up to 4-5 inches deep so you must saturate the area and let dry. Also since its been there a while it will take 2-3 applications. Hope this helps. Good luck!  Mark

exring answered 4 years ago

If you really want to get rid of the urine smell in the concrete, there is a product on the web that really does work if you follow the instructions. Concrete can be on of the toughest materials to fix, but it is really pretty easy with this product. Check out for the full story