I'll try to be as succinct as I can but this situation has been ongoing and very strange. We moved into our new build home in September 2023. Within a week of moving, we notice mouse droppings and a LOT of them upon waking up in the morning (probably over 20 droppings throughout our first floor). My husband sets traps out that evening (at least 8 of them) and we leave for a few hours to go to a friend's house. Upon returning, none of the traps had been triggered, but the mouse (or other rodent?) licked all of the peanut butter and almonds we put on the traps. All 8 of them were licked clean. We continue to set out traps and they are untouched.

A few days pass and we don't see anymore droppings and with the traps untouched, we figure the mouse escaped. Until one day we noticed a propane smell. We immediately go outside and call our project manager who comes out and inspects. He sends over professionals to test every gas line and no leaks were found. But we all notice that the "gas smell" was coming from the first floor powder room and it was STRONG. There are no gas lines near the powder room, so we all figured it must be a decomposing rodent that escaped our traps. I Google'd to see if dead rodents can emit a propane smell and find that they can. There's an office beside the powder room that had framing set for pocket doors (but the doors had not yet arrived), so we figured the rodent got into the walls from the pocket door opening somehow. For days we leave the windows open as much as possible to rid of the smell, run air purifiers and finally after about 5 days, it seems to go away. By that time, it was fall and we stopped opening windows due to the cold.

Fast forward through winter and absolutely no propane smell AT ALL...unless we happen to open a window. On a couple of nice days or when doing heavy cleaning, we open windows and within an hour or two the propane/dead rodent smell is back with a vengeance. This even happens if we open a window on the 2nd floor. Just one window open a crack is all it takes to bring back the smell. The smell is still concentrated in the powder room, but goes up into the hallway of the 2nd and 3rd floors.

So we're at a loss here. We purchased a gas leak detector of our own and we've never had any high readings. Can a dead rodent really take this long to decompose? Do we need to rip out the powder room walls at this point? And why in the world can we only smell this when the windows are open? Any insight would be greatly appreciated! I feel like I'm losing my mind here!