Horrible smell in stairwells after rain...

chispJuly 12, 2006

We bought a house about seven months ago, and have noticed an awful smell that seems to increase after a rainfall. The smell is concentrated in the basement, but in the finished area, not the unfinished laundry room or crawl space. We finished the basement when we moved in.

It's also detectable in the three stairways (it's a split). The smell is somewhere between dead animal, rotten fish and just plain gross. At first I was sure it was some sort of dead critter, but since it has persisted for at least six months and is worst after rain, I figure it might have to do with moisture/mold something like that. Any suggestions or ideas would be much appreciated.



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Well, one thing occurs to me. I rented a house with a crawl space under it that got very wet when it rained due to poor drainage (none) on the property. At some point there had been a sewage back up and the cleanout opened under the house (old toilet paper evidence was still in place). As long as it was dry, no smell. Moisture would activate the yuck. A plumber suggested sewage digestive enzymes be spread under the house. Is this a maybe? Can you peek into the crawl space? Do you know the location of your sewer line cleanout?

    Bookmark   July 13, 2006 at 8:32PM
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We have a bilevel, 3/4 finished lower level, the utility room is concrete. Prior owners had put carpeting downstairs, did not have central air and never used a dehumidifier. Shortly after we moved in, every time it got really humid or rained, the smell of mildew was really unpleasant in the lower level carpeted rooms. Too much moisture in the carpet. We yanked up the carpet and put down laminate with a rubber underside for use on concrete, and replaced the carpeted stair treads with new oak, and the smell has not recurred since. (I was certain we'd find moldy padding, but we didn't.)

Does the smell dissipate if you close the windows and run the furnace fan or AC and a dehumidifier?

If it really bowls you over, you might be looking at sewer or plumbing issues. With regard to plumbing: Do you by chance use the upstairs bath primarily, and have a secondary bath in your lower level that doesn't get as much use? I ask because of a situation we encountered. We have a rental property that had senior tenants. She swore she smelled a foul smell after rain, but he didn't. No one else could detect it either. I happened to have a plumber out routing the basement line and mentioned the smell to him, he said the pipes in the basement were all "open" and good. She insisted it still smelled, primarily from the tub. I was talking to the town's water department engineer one day about a different matter, mentioned this to him. He asked a bunch of questions, turns out they were not running enough water through the lines. (They were on the frugal side, opting for sponge bathing more than showering. ) He suggested I fill up the tub and all sinks with hot water and liquid Lysol (a full bottle in the tub, split another bottle between the sinks). He told me be sure to force plenty of lysol/water into the overflow drain at the top of the tub and sinks as well. I did this, then let everything drain and ran fresh water through after the Lysol. He said plumbing needs to be kept "moist", or gases will accumulate. He said homeowners should do this procedure (fresh water is OK, lysol mainly for first use) at least weekly in bathrooms/sinks/showers that are not used at least several times a week.
But if it's sewer gas, that can be very serious to your health. Maybe check with the plumbing forum here?

    Bookmark   July 14, 2006 at 9:17AM
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Thanks to both of you for the input. We have engineered hardwood over the concrete, so it's not a carpet issue. I tried pouring liquid lysol then running lots of water down the bathroom sink, but the smell is still pretty strong. It's been sunny with no rain here all of today, and the stink is still there. The crawl space doesn't smell at all. We installed a new sump pump before we finished the basement, so I'm not sure what it could be. It's very fishy (literally and figuratively).

    Bookmark   July 14, 2006 at 5:44PM
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We solved the mystery. It was the cheap recessed lighting in the basement...the plastic globes were overheating and starting to melt because we the lightbulbs we had in were high wattage. I guess the reason it seemed worse after rain was that the kids spend more time down there when it's raining and the lights were always on.

    Bookmark   July 16, 2006 at 11:11AM
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Ah, that's a new one ;) Glad you found the source of the trouble, a very tricky one to track down, no less!

    Bookmark   July 17, 2006 at 6:43AM
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I am experiencing a similiar issue, did you have to replace the fixtures or did you opt for lower wattage bulbs? Were you able to fix the problem? Thanks!

    Bookmark   November 7, 2006 at 6:19PM
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We had this same dead animal smell or rotten fish smell in our basement when we were trying to sell our home. It only came when we had showings (when we would turn the lights on) so I googled the smell and issue and luckily came accross this thread. We too had recessed lighting in the basement and the bulbs (only 60 watts) were browning and slightly melting the plastic casings. Very easy fix. If you turn the lights off and probably to be safe the power too, and then unhook the springs that hold the plastic part of the recessed lights up the plastic piece will come down. Take them to Lowes or Home Depot and match them up with new ones. Before you install the new ones there is a nut to adjust the part of the recessed light that holds the bulb; the lower the better as the bulb should stick out from the ceiling I was told by someone who knows how to install properly. If the part that holds the bulb holds the bulb too far up the heat has no way to escape and will heat the plastic. I also opted for fluorescent bulbs as they do not put out much heat. I thought the light that would be generated by flourescent bulbs would not be as appealing but it was actually much softer and nicer along with less heat. I hope this post helps others. We had many people interested in our home but we could not figure out the smell. Thanks, Kevin

    Bookmark   April 17, 2011 at 9:46PM
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