# Mold odors emanating from roof vent. **URL:** \ **Category:** Factual Questions\ **Created:** [October 10, 2013, 4:15pm UTC](https://boards.straightdope.com/t/mold-odors-emanating-from-roof-vent/670883 "2013-10-10T16:15:21Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![beth97202](https://avatars.discourse-cdn.com/v4/letter/b/a6a055/32.png) [@beth97202](https://boards.straightdope.com/u/beth97202)\ **Post date:** [October 10, 2013, 4:15pm UTC](https://boards.straightdope.com/t/mold-odors-emanating-from-roof-vent/670883/1 "2013-10-10T16:15:21Z")
I have a basement bathroom that has developed a strong moldy/musty odor with occasional mild sewer gas odor. The odor does not seem to be coming from either sink or shower drain. I have cleaned both with baking soda and vinegar with no positive results. When inspecting roof vent, discovered same strong odor and some standing water where the vent was stepped down to a smaller pipe about 6 ft. down. Flushed vent pipe with lots of water and then added about half a gallon of diluted bleach. Odor in bathroom still persists. What next? ---
**Author:** ![sitchensis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sitchensis/32/4892_2.png) [@sitchensis](https://boards.straightdope.com/u/sitchensis)\ **Post date:** [October 10, 2013, 4:23pm UTC](https://boards.straightdope.com/t/mold-odors-emanating-from-roof-vent/670883/2 "2013-10-10T16:23:48Z")
How often do the sink and shower get used? ---
**Author:** ![Muffin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muffin/32/4341_2.png) [@Muffin](https://boards.straightdope.com/u/Muffin)\ **Post date:** [October 10, 2013, 4:59pm UTC](https://boards.straightdope.com/t/mold-odors-emanating-from-roof-vent/670883/3 "2013-10-10T16:59:35Z")
Fog the room and the vent with [Concrobium](http://www.concrobium.com/); repeat as often as necessary. ---
**Author:** ![beth97202](https://avatars.discourse-cdn.com/v4/letter/b/a6a055/32.png) [@beth97202](https://boards.straightdope.com/u/beth97202)\ **Post date:** [October 10, 2013, 11:12pm UTC](https://boards.straightdope.com/t/mold-odors-emanating-from-roof-vent/670883/4 "2013-10-10T23:12:39Z")
shower/sink get used every day ---
**Author:** ![sitchensis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sitchensis/32/4892_2.png) [@sitchensis](https://boards.straightdope.com/u/sitchensis)\ **Post date:** [October 11, 2013, 4:05am UTC](https://boards.straightdope.com/t/mold-odors-emanating-from-roof-vent/670883/5 "2013-10-11T04:05:34Z")
> [@beth97202](#): > > shower/sink get used every day Well my first thought was that the water in your traps was evaporating over time but that’s not the case. Do you have a strong bathroom fan that you use after showers? Along with that, are you seeing any discoloration/mold in the corners of the ceiling? ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [October 11, 2013, 4:40am UTC](https://boards.straightdope.com/t/mold-odors-emanating-from-roof-vent/670883/6 "2013-10-11T04:40:13Z")
a basement bathroom would tend to be humid/damp and not well ventilated, so likely for some mildew, give it a soap scrub and keep the door open. a roof vent is likely to be mildew stick and sewer stink all the time. ---
**Author:** ![harryrancic](https://avatars.discourse-cdn.com/v4/letter/h/e9c0ed/32.png) [@harryrancic](https://boards.straightdope.com/u/harryrancic)\ **Post date:** [November 4, 2013, 11:20am UTC](https://boards.straightdope.com/t/mold-odors-emanating-from-roof-vent/670883/7 "2013-11-04T11:20:19Z")
> [@beth97202](#): > > I have a basement bathroom that has developed a strong moldy/musty odor with occasional mild sewer gas odor. The odor does not seem to be coming from either sink or shower drain. I have cleaned both with baking soda and vinegar with no positive results. When inspecting roof vent, discovered same strong odor and some standing water where the vent was stepped down to a smaller pipe about 6 ft. down. Flushed vent pipe with lots of water and then added about half a gallon of diluted bleach. Odor in bathroom still persists. What next? what do you think - how much would that cost to get a roofer? ---
**Author:** ![california\_jobcase](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@california\_jobcase](https://boards.straightdope.com/u/california_jobcase)\ **Post date:** [November 5, 2013, 4:59pm UTC](https://boards.straightdope.com/t/mold-odors-emanating-from-roof-vent/670883/8 "2013-11-05T16:59:43Z")
Does the bathroom have a floor drain?