Hi - a lot of these posts seem to be slightly different but thought I would share my experience in my home that may prove helpful or be similar. My wife and I moved to our home newly built 5 years ago tomorrow! I can't say I've noticed the smell in the first year but maybe it's poor memory. After the first year, we'd notice this propane/rotten/dead animal like smell. At first I thought the builder put something in the vents - no signs of any rodents ever and ruled this out. Next I checked the line/drain from the AC/furnace and even had a tech check and clean the pump - no help. plumber says there is no issue with drainage or sewer or any back up venting - ok. what HAS helped intermittently is calling the gas company to check the gas lines inside. I've had them 7 times in the past 2 years, each time they find a small leak - nothing major, no reading except with the sniffer right at the source of the leak. {I also have multiple CO and gas detectors on the floor (heavy gas). They have never gone off}. After the gas company repairs the pipe the smell is gone for a few weeks maybe months depending on warm or cold season. It comes back, gas company is back out and repeat. I have replaced two ovens in the kitchen due to them being the source of the leak. I find that the air return on the main level of my house sucks in the smell and returns it to the furnace. When the furnace kicks on we smell it out of the vents. Occasionally I can smell it in the room where the furnace is also. Gas company has done line checks, pressure checks, fixed leaks - I've paid them thousands to come out and fix this over and over then the smell returns - I've returned two "new" ovens due to leaks after minimal use. I have a 2 yr old son and new baby due in a month and NEED this resolved. Please let me know if you have any suggestions or have been through something similar.

All kinds of good info right here. Thanks so much. We will def. get sewer protection although I don't think it's a factor at play here (we have no problem flushing i.e.). We will probably look at replacing the gaskets on the toilet (specially the downstairs one where it smells more). The vents in the attic/roof were checked by (a good) inspector - and they were fine. I'd be surprised if they suddenly got clogged (I'll check in the attic just to be sure, of course). But the riser pipes disconnect behind the walls somewhere is intriguing and probably the best bet right now. If I'm understanding this right - a bad sewer riser pipe would manifest itself as we observe it - a smell ONLY in the bathrooms (strongest in the downstairs' bathroom). Does that make sense? Short of breaking the wall any other way to convince ourselves that that is a likely cause? Thanks so much for this great advice!

I grew up on a dairy farm in N.E.Ohio. We had a huge old farmhouse with 7BR and a #2 galvanized tub and chamber pots for a bathroom, + the little house out back...LOL The basement had a dirt floor and stone walls. There was two 4'x4'x25' bins, one along the east wall and the second running parallel with a 3' walkway where we stored 10tons of potatoes + pumpkins, squash, and apples. A row of 18 fifty gallon barrels filled with apple cider, which provided sweet cider for about 4 to 6 weeks, then hard cider for the men all winter & spring and apple vinegar for the canning season the next year. The south wall had shelves where we stored 2000 mason canning jars filled with every fruit and veggie imaginable + about 10 varieties of pickles and home canned pork sausage balls. Huge smoked hams (35-40lbs) hung on hooks from the ceiling along with sides of bacon and smoked sausages. Every morning when we finished milking the cows we would bring a 5gallon pail of fresh whole milk to the house (6-8% butterfat). AT the barn we had a small masonary building called the Milk house. In the milk house there was a pit 4' wide, 3'deep and 14' long with a pipe coming in from the spring on one end and a drain pipe on the opposite end. We stored up to 18 milk cans of milk in that pit overnite, then after the milking in the morning we hauled all the milk cans to a local dairy. We didn't have need of a butter churn because the dairy gave us 4lbs of butter every day free. (I used to love riding the truck to the dairy because we could sneak in the freezers and grab an ice cream bar..LOL) Twenty loaves of bread were baked every Thursday along with a couple pies and yeast dinner rolls. Until I was 13 years old we didn't even have a refrigerator and didn't see any need of getting one. Now the doomsday profits would tell you that all that fresh milk, smoked meats and non-refrigerated food will kill you, but I am 60yrs old and never even saw a doctor from the time i discharged out of the Air Force in 1972 until two months ago. My Grandfather was 68 when he passed away, worked the farm with horses every day, and he had never been to a doctor in his life. go figure!

I thought the same thing about the condenser unit. An air conditioner makes the air cold by running it over refrigerated coils and the result is that humidity in the air comes out and has to be drained away. Air conditioners have a hose that should lead to a drain. Your hose or drain may be plugged. You are going to need a contractor to take out the drywall in this room, possibly finding molding or rotting ceiling rafters underneath the ceiling once it is removed. I do not know what qualifies something to need mold remediation, but this may need to be removed carefully in accordance with mold remediation rules so that the spores are contained and are not blown all over your house and the workers are going to need respirators and disposable overalls, I would think. You are going down to the house framing, possibly reframing bad wood, and building up from there. We had a house with a previous leak in one room. I knew about it because a man who previously rented the home saw me raking the leaves and stopped to talk to me about it. He said that they had garbage cans in that room to catch the leaks. I do not know if the seller had re-drywalled the room before I bought it. Our drywall was in good condition from inside the room. We had developed some mold at the floor level on the outer walls, though, following some ice dams that caused big leaks. I had the builder remove the drywall on those walls. I told him to take off the drywall until it was clean and had no mold. I came home to a room open to the roof. With rotting rafters. Some were almost eaten away and my builder had to sister about six of them. He also tore off the roof and put ice and water shield over the entire room (it was a former porch with a shed roof coming off the main roof) and re-roofed it. I am wondering if your air conditioning unit is going to come through your ceiling due to rotten rafters. There is a product that I did not know about then that contractors on this forum have recommended as the proper thing to use for mold. Concrobium is what you use, not bleach. Bleach is not able to kill the mold as well. Once you rebuild the room, you need a bathroom vent fan that vents out through the roof. Get one that operates on a humidistat or a motion sensor and you will not need everyone to remember to turn it on before they start to shower.