We have an "on again, off again" odor problem in our home. Our house is about 40 years old. We have lived in it about 5 years. We have had this odor problem on and off since we moved in.

The house is a 2-story split level. Because it is a split level, you can enter the top level from the front of the house and you can exit the lower level from the back of the house. The furnace and condensate line for the AC are located in 1 room in the corner of the house on the lower level. The 2 rooms adjacent to the furnace room are where the odor is smelled - nowhere else in the house. The 2 rooms share a wall with the furnace room, and one room also contains a gas fireplace.

I can only describe the smell as somewhat sweet, but rancid. I go back and forth between believing it is a sewer smell and believing it is a dead mouse. We live in a heavily wooded area and mice are a problem.

I do not believe we have a sump pump - we sit high on our property and I don't think there is a need for one. We never notice the smell in the winter. It is usually in the summer months. Last summer we had the AC serviced and the condensate pan cleaned. This did not resolve the issue. 2 days ago we noticed the odor again - it seems "early" this year as we typically associate it with running the AC - although like I mentioned it is not a constant smell.

I have had pest control people out and they insist it is a sewer problem. Plumbers say it is a pest problem. Sigh.

We did get a very heavy rain the day before the smell started again. I am starting to wonder if that is related. I will start to pay attention to the correlation between weather and the smell. I also wonder if this could be related to rotting wood? Is moisture causing the problem? There are no signs of mold anywhere and I am sensitive to moisture issues and do not believe we have a problem that would warrant a dehumidifier, etc.

Please help!

You are correct about the rain causing your problem. You just might have to invest in some kind of sump pump to really get rid of the smell forever. There is something in the soil under the house that is affected by the rainwater. Problem is you have to figure out just where it is. Don't know about a dehumidifier helping, but you may want to try that. They do draw a lot of current though and can run up your electric bill. I think sump pumps draw a lot less current.

Have you checked the floor drain trap to be sure it has liquid in it? Smells always get worse in rainy weather. The air's heavier and brings the smells closed to the ground. What fixtures are in the rooms affected? Back to you. Tom

Does sound like a moisture problem. You may check around the house to make sure your down spouts are discharging water away from the house and make sue the grades are sloping away from the hose. This may help keep any moisture from getting under if that is what is causing the smell.

Have you checked the floor drain trap to be sure it has liquid in it? Smells always get worse in rainy weather. The air's heavier and brings the smells closed to the ground. What fixtures are in the rooms affected? Back to you. Tom


Hi Tom - thanks for your thoughts - and all the other posts.

We have a very strange floor drain - it is enclosed in the foundation. The AC condensate runs into this drain, but essentially the piping from the AC runs directly into the cement floor and I can't access the drain. I would describe it as more like a drainage line than a drain. I have flushed it before - it didn't help - do I need to regularly add water to it? If so, plain water or bleach and water?

Regarding the fixtures in the rooms affected, I'm not sure what you mean. The 2 rooms have standard air vents and returns for HVAC. One room has a gas fireplace.

I guess I will try adding water to this drainage line and I call someone about installing a sump pump and see what they say. All the discharge lines from the house are clear and the landscaping is sloped away from the house


Thanks!

Sweet and rancid don't describe sewer gas but can match with a dead mouse. The on again off again isue, does the smell last for about 7-10 days and then disappears slowly? That would be a mouse. Sewer gas smells just like you think, a bit like a gaseous emission as my kids would say, I had a different word in mind but we'll accept their wording.

Sweet and rancid don't discribe sewer gas but can match with a dead mouse. The on again off again isue, does the smell last for about 7-10 days and then disappears slowly?? That would be a mouse. Sewer gas smells just like you think, a bit like a gaseous emission as my kids would say, I had a different word in mind but we'll accept their wording.


I have a very difficult time describing the smell. Maybe rancid isn't right. It does have a sweet undertone, but it doesn't smell as pungent as I would expect sewer gas to smell. But it doesn't smell good.

It doesn't usually last as long as you suggest - about 4-5 days and then it fades slowly. The reason I have suspect water/sewer over mouse is that it smells the same every time. Exactly the same. I would think mice might not be so consistent :) It also seems unlikely that mice are coming into the house mid-summer, right? I have a pest service - I will pay more attention to activity levels by season...


How can I know whether it is mouse or sewer if the 'experts' I've had in my home disagree about the cause/source?


Thanks!

We live in a heavily wooded area and mice are a problem.

Have you ever noticed this odor on the outside of the house in this area?
What's the landscaping around the area outside the two rooms?

Have you ever noticed this odor on the outside of the house in this area?
What's the landscaping around the area outside the two rooms?



No odor outside the house. One room has a brick patio off 1 exterior wall; the other exterior wall has sloping mulching with a few plants and pachysandra ground cover - this is also what is behind the 'furnace room.' The 2nd room is partially underground (its a split) so the ground is about 2/3 up that exterior wall - again sloping mulching with some bushes. I verified the drain pipes are all clear and they run about 20 feet away from the house before discharging. Next rain I'll ensure no leaks... If I survive until then :D


I filled the drain trap yesterday - to no avail. Is it possible I didn't add enough water?


Thanks!

We have a very strange floor drain - it is enclosed in the foundation. The AC condensate runs into this drain, but essentially the piping from the AC runs directly into the cement floor and I can't access the drain. I would describe it as more like a drainage line than a drain. Are you saying you can't look down to see if it's trapped or not?
It's possible that you're 100% correct. That you, indeed, have a drainage line instead of a floor drain with a trap. If that's the case you have located the source of your bad smell.
I filled the drain trap yesterday What trap? The floor drain buried in the foundation? Lets have more details. Let me know. Tom

OK, everybody can give me the horse laugh but I'm going to say this anyway.
I discount mice. It's been going on to long, you said 4 or 5 years. Also to intermittent to be sewer gas if you have done nothing to correct it when it occurs. I don't know why, maybe it's the way you describe the odor and a wooded home site but a skunk comes to mind. Could you have one of these furry friends coming to visit at night occasionally. Don't know much about them but I do know that the odor will linger where they habitually travel. Kind of explains the seasonal aspects. Either around the house or the area where the pipes drain to if the drains are not trapped. Maybe your "experts" were both right.

I know I'm weird.

Are you saying you can't look down to see if it's trapped or not?
It's possible that you're 100% correct. That you, indeed, have a drainage line instead of a floor drain with a trap. If that's the case you have located the source of your bad smell. What trap? The floor drain burried in the foundation? Lets have more details. Let me know. Tom


Hi Tom,


I can't see anything other than a PVC line running from my AC into my cement floor. It is vented, so I can easily add water, which is what I have been doing to make sure that if there is a trap under ground (is that possible? ) that it is full of water. (incendentally, it doesn't smell IN the furnace room where this line is vented... ) I would describe it as a drainage line, not a drain, as I cannot access any drain without cracking open the cement. Do I need to have that dug up and replaced with a drain? Flush it with bleach? Both?



There are no other open drains in the lower level. There must be a drain somewhere near/under my washing machine, but that is in the other corner of the house (same level), adjacent to a bathroom and a slop sink. The odor isn't present there, so I have ruled out any issues with those drains. They are used frequently and we've never had any backups, etc. in those drains.

What do you think now?


Thanks
Erin